501PERFORMANCE-BASED STRUCTURAL CONCRETE

501

501.01DESCRIPTION . This work shall consist of designing, furnishing, and placing performance -based

Portland cement concrete for structures and incidental construction. The Portland cement concrete may consist of a homogeneous mixture of cement, fine aggregate, coarse aggregate, water, admixtures, and pozzolans, proportioned and mixed according to these specifications.

501.02MATERIALS . Materials shall meet the requirements of the following subsections:

Portland Cement ................................ ................................ ................................ ......... 701.02 Portland -Pozzolan Cement ................................ ................................ ......................... 701.04 Portland -Limestone Cement ................................ ................................ ...................... 701.05 Portland Blast -Furnace Slag Cement ................................ ................................ ......... 701.06 Ternary Blended Cement ................................ ................................ ........................... 701.07 Fine Aggregate for Concrete ................................ ................................ ...................... 704.01 Coarse Aggregate for Concrete ................................ ................................ .................. 704.02 Lightweight Coarse Aggregate for Concrete ................................ ............................. 704.14 Lightweight Fine Aggregate for Concrete ................................ ................................ .704.19 Preformed Joint Filler, Cork, and Asphalt -Treated Felt ................................ ............ 707.0 6 Polyvinyl Chloride (PVC) Waters top ................................ ................................ ........ 707.08 Concrete Bonding Systems ................................ ................................ ........................ 707.1 4 Steel for Corrugated Metal Forms ................................ ................................ ............. 715.0 3 Epoxy Bonding Systems ................................ ................................ ............................ 719.01 Concrete Curing Materials ................................ ................................ ......................... 725.01 Air-Entraining Admixtures ................................ ................................ ........................ 725.02(b) Retarding Admixtures ................................ ................................ ................................ 725.02(c) Latex Admixtures ................................ ................................ ................................ .......725.02(d) Water -Reducing Admixtures ................................ ................................ ..................... 725.02(e) Water -Reducing and Retarding Admixtures ................................ .............................. 725.02(f) Water -Reducing, High Range Admixtures ................................ ................................ 725.02(g) Water -Reducing, High Range, and Retarding Admixtures ................................ .......725.02(h) Accelerating Admixtures ................................ ................................ ........................... 725.02(i)

501

5-2Water -Reducing and A ccelerating Admixtures ................................ ......................... 725.02(j)

Specific Performance Admixtures ................................ ................................ ............. 725.02(k) Anti-Washout Admixtures ................................ ................................ ......................... 725.02(l) Pozzolans ................................ ................................ ................................ ................... 725.03(a) Silica Fume ................................ ................................ ................................ ................ 725.03(b) Ground Granulated Blast -Furnace Slag (GGBFS) ................................ .................... 725.03(c) Polystyrene Insulation Board ................................ ................................ ..................... 735.01 Blanket Insulation Material ................................ ................................ ........................ 735.02 Pipe Insulation ................................ ................................ ................................ ........... 740.06 Water ................................ ................................ ................................ .......................... 745.01 Concrete Repair Materials ................................ ................................ ......................... 780.01 Normal weight coarse aggregate for superstructures shall be conditioned so that the total moisture percentage shall be the absorption percentage plus, at a mini mum, 0.25% free moisture for the aggregate.

501.03CLASSIFICATION AND PROPORTIONING . Concrete shall meet the requirements specified in

Table 501.03A and shall be used as shown on the Plans. TABLE 501.03A – PERFORMANCE -BASED CONCRETE CLASSES AND PROPERTIES Concrete Class 1 Min. 56 -Day Comp . Strength

W/CM Ratio 3 Max. VSI 4 Slump/ Spread Limit Freeze/Thaw Durability 5 Air Content Limits 6 Max. Free Shrinkage Max. 56 - Day Surface Resistivity 7 Min. Durability Factor Max. Air Void Spacing Factor (in.) PCD 4,000 TBD -- N/A 8 80 0.008 TBD 0.032% Low PCS 3,500 TBD -- N/A 8 80 0.008 TBD 0.042% Low SCC 4,000 TBD 1 TBD 9 80 0.008 TBD TBD 10 Low 1 PCD = Performance Concrete, Deck PCS = Performance Concrete, Substructure SCC = Self -Consolidating Concrete 2 The concrete may be accepted if the design compressive strength from standard cured cylinders has been obtained at 28 days. Any 56 day acceptance cylinders shall be tested regardless of the results of earlier tests. 3 The maximum W/CM ratio shall be deter mined by the Contractor as established by mix qualification testing. During production, the W/CM ratio shall be less than or equal to the W/CM ratio from the approved qualification mix. See Subsection 501.03(b) . The W/CM ratio shall be rounded to two decimal places in accordance with ASTM E29 . 4 Visual stability index (VSI) as determined in accordance with ASTM C1611 . 5 The freeze/thaw durability of the proposed mix design may be established by providing mix qualification testing demonstrating conformance with either of the two requirements. Testing shall meet the requirements of either AASHTO T 161, Procedure A , or ASTM C457 , as applicable. See Subsection 501.03(b)(2) .

501 5-3 6 The minimum air content shall be determined by the Contractor as established by mix qualification testing. During production, the air content shall be greater than or equal to the air content from the ap proved qualification mix. See Subsection 501.03(b)(2) . 7 The Contractor shall determine the surface resistivity in accordance with Subsection 501.03( b)(4). 8 The mix shall not exhibit segregation. If the mix does exhibit segregation, the load shall be rejected . If the spread is equal to or exceeds 20 inches, the mix shall be classified as Class SCC concrete. 9 The Contractor shall determine the spread limits in accordance with Subsection 501.03(b)( 5). The spread shall be maintained within the determine d spread limits for the placement. The mix shall not exhibit segregation. If the mix does exhibit segregation or exceeds the upper spread limit, the load shall be rejected . and subsequent loads shall be tested by the Contractor until the mix meets the allo wable limits. The Engineer may perform a J -ring test at the time of placement if blocking is a concern. 10 The Contractor shall determine the free shrinkage in accordance with Subsection 501.03( b)(1) . Class SCC concrete will be allowed for use in superstru cture elements if the free shrinkage meets the requirements for Class PCD. Class SCC concrete will be allowed for use in substructure elements if the free shrinkage meets the requirements for Class PCS. If a nominal maximum aggregate size is not specified, the Contractor shall determine the nominal maximum aggregate size using guidance from ACI 211.1 . In no case shall the maximum aggregate size exceed 1/5 of the narrowest dimension between sides of the forms, 1/3 the depth of slabs, or 3/4 of the minimum clear spacing between individual reinforcing bars, bundles of bars, or pre -tensioning strands unless approved by the Engineer. The Contractor may use industry methods to develop gradations not specified in Section 704 that are better optimized to satisfy the required concrete performance characteristics. If the Contractor is using a combined gradation, they shall provide the method or methods of how they will monitor gradation, the limits of the gradation ranges, and the frequency of monitoring. Lightweight fine aggregate may be used to replace up to 30% of the volume of normal weight sand. The gradation of the lightweight fine aggregate shall conform to the requirements of AASHTO M 195 . The lightweight fi ne aggregate shall be conditioned for enough time to fully saturate the material. The stockpile shall be constructed so that the moisture content is uniform throughout the pile. The stockpile will be allowed to drain 12 hours to 15 hours immediately prior to use, unless an alternate procedure is approved by the Structural Concrete Engineer. The Contractor shall state the method, duration and procedure used to confirm that the material is at or above its saturated surface dry (SSD) value, by weight, througho ut the pile. The use of chlorides or admixtures containing chlorides is prohibited. All admixtures will be considered incidental to the work and included in the Contract unit price of the concrete.

501

5-4The concrete materials may be proportioned using the absolute volumes method in accordance with the

specified requirements. The volumetric proportioning method , such as that outlined in ACI 211.1 or other approved volumetric proportioning meth ods, shall be employed in the mix design. Prior to placing concrete on the project (or prior to the trial pour or the pre -placement meeting, whichever occurs first), the Contractor shall submit for approval the single mix design formula that satisfies all mix design qualification requirements and testing for the class of concrete specified. The mix designs shall be submitted to the Structural Concrete Engineer at the Agency’s Materials Testing and Certification Section Central Laboratory. The Structural Co ncrete Engineer may require a minimum of 8 weeks for testing, review, and approval of new mix designs. No class of concrete shall be placed on a project, including the trial pour, until the mix design is approved. If the proposed performance concrete mix design fails to meet the qualification requirements, the Contractor shall submit a revised mix design formula in writing to address the mix qualification deficiencies of the original failed mix design. Review of the revised mix design formula by the Stru ctural Concrete Engineer will be completed within 14 calendar days. Upon approval of the revised mix design formula by the Structural Concrete Engineer, testing of the revised mix design may commence. Testing of the revised mix design formula shall be comp leted within 6 months of the revised mix design formula approval. Until the testing of the revised mix design formula is completed and approved, the Structural Concrete Engineer will specify the use of an alternative, prescriptive mix design formula for th e application in question, including appropriate acceptance requirements for the prescriptive alternative mix. .

501

Concrete test mixes shall be used to obtain the test results where applicable. All wet testing shall

be done by personnel with current ACI Concrete Field Testing Technician Grade I certifications.

All other tests shall be performed by a laboratory that is accredited by AASHTO re:source or the

Concrete and Cement Reference Laboratory (CCRL) in the particular test method, or as allowed

by the Engineer. All test reports pertaining to the qualification testing shall be date traceable to

concrete test batches whether produced at a concrete producer’s facility or an independent

laboratory facility. All qualification batches shall have weight tickets and fresh concrete property

test results included.

be performed in accordance with AASHTO R 60 on a qualification batch of concrete that is a

minimum of 3 cubic yards. Specimens for tests to determine freeze-thaw durability, strength,

surface resistivity, and SCC spread limits shall be made from the qualification batch. The

qualification batch shall also be tested for air content (AASHTO T 152), concrete temperature

(ASTM C1064), and unit weight (AASHTO T 121). The air content value and the water/

cementitious materials ratio of the material used to pass the mix qualification tests shall become

the minimum air content value and the maximum water/cementitious materials ratio allowed

during production.

The free shrinkage specimens may be obtained from the qualification batch, except the Contractor

will be required to submit a plan on how they will comply with AASHTO T 160, Section 10, which

shall be approved by the Structural Concrete Engineer prior to the beginning of qualification

testing.

concrete. The free shrinkage rate of the concrete shall be tested per the requirements of

AASHTO T 160. The cross-section of the prism shall be 4 inches × 4 inches. The

requirements of AASHTO T 160, Section 11.1.2 shall be followed for storage and

measurements, and all specified test age results shall be submitted. Specimen testing may

be terminated after 28 days of drying.

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Testing shall be performed by a laboratory accredited in the specific test method. Concrete

produced by the testing laboratory to make the specimens shall have an air content equal

to the Contractors proposed minimum air content with a tolerance of + 1%. The air content

value from laboratory produced concrete used for this testing will not be considered in

determination of the minimum air content value allowed during production.

concrete. At the Contractor’s choice, either AASHTO T 161 or ASTM C457 may be used to

demonstrate freeze/thaw durability meeting the specification requirements.

The durability factor shall be tested in accordance with AASHTO T 161, Procedure A.

The air void spacing factor shall be tested in accordance with ASTM C457. The Contractor

shall make a minimum of two concrete cylinders per AASHTO R 100 and report the average

air-void spacing factor obtained from testing these two specimens. The cylinders shall be

cured for a minimum of 5 days prior to being tested according to the requirements of ASTM

C457.

The air content of the qualification batch that passes the chosen freeze-thaw durability

testing shall become the minimum air content allowed in production. This shall also

become the minimum air content allowed for all subsequent mix qualification testing,

unless otherwise stated.

AASHTO T 22 for 28 day and 56 day standard cured cylinders.

requirements of AASHTO T 358. Results shall be categorized as Low, Very Low, or

Negligible in accordance with AASHTO T 358, Table 1. The surface resistivity may be

accepted prior to 56 days if the results meet these requirements. The 56 day test results

shall be completed and submitted regardless of the results of earlier tests.

ASTM C1621 shall be performed at the proposed upper and lower spread limits. Each

spread limit shall not exceed a blocking assessment of “Minimal to Noticeable Blocking”.

The slump cone shall be filled in accordance with ASTM C1621, Procedure B. At both the

upper and lower limits, the visual stability index (VSI) shall not be greater than 1.

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measured separately based on the requirements of AASHTO T 303 or ASTM C1260. If one or more

of the aggregates exceeds 0.10% expansion, then the aggregate shall be tested again according to

the requirements of ASTM C1567 or CRD-C 662.

The Contractor may elect to go directly to ASTM C1567, or CRD-C 662 if using lithium nitrate, if

they suspect that the aggregate may exceed the 0.10% expansion if tested by AASHTO T 303 or

ASTM C1260.

If a lithium nitrate admixture will be used, no matter the cementitious materials combination, each

aggregate will be tested by CRD-C 662. CRD-C 662, Section 9 shall be replaced using ASTM

C1567, Section 9.

The aggregates shall not exceed 0.10% expansion when tested by any of the four allowable test

methods.

Testing shall be performed by a laboratory accredited in the ASTM C1260, ASTM C1567, or

AASHTO T303 test method.

Test results shall be submitted with the mix design.

reviewed and approved by the Structural Concrete Engineer, no changes to the mix design shall

be allowed except as defined in Table 501.03B. Following an approved change in accordance with

Table 501.03B, the Contractor may still revert to the original approved mix design formulation. If

a source change is requested due to a change in product or material name that does not include any

significant change in product formulation or material characteristic, and this is substantiated by

the product or material supplier in writing, re-testing is not required.

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TABLE 501.03B – ALLOWABLE MIX DESIGN CHANGES FOR ALL MIX TYPES

Previously Approved

Component or Property Being

Changed

Mix Design Resubmittal Requirements

No. of

Changes

Allowed

Cement source

If the alkali content (Na and K) of the new source is greater than that of the

original source, and the original result from Subsection 501.03(c) was

greater than 0.08% expansion, then updated ASR testing is required.

Otherwise, no qualification testing is required.

Unlimited

Cement proportioning (± 5% by

volume) No qualification testing required One

Aggregate proportioning (±

10% by volume) No qualification testing required One

Aggregate source ASR testing and gradation check by original Contractor method One

Slag source If same grade is used, no qualification testing required Unlimited

Silica fume source No qualification testing required Unlimited

Fly ash source

If either the calcium (CaO) or the alkali (Na and K) content of the new

source is greater than that of the original source, and the original result

from Subsection 501.03(c) was greater than 0.08% expansion, then updated

ASR testing is required. Otherwise, no qualification testing is required.

Unlimited

Air-entraining admixture source

(Subsection 725.02(b)) Resubmittal of freeze/thaw durability qualification testing Unlimited

Shrinkage reducing admixture

source (Subsection 725.02(k)) Resubmittal of shrinkage qualification testing Unlimited

Corrosion inhibiting admixture

source (Subsection 725.02(k))

Resubmittal of shrinkage qualification testing. If shrinkage qualification

testing of the original mix design is greater than 70% of shrinkage limit,

then updated shrinkage testing is required.

Unlimited

Latex admixture source

(Subsection 725.02(d)) Resubmittal of surface resistivity testing Unlimited

Accelerating admixture dosage

increase (Subsection 725.02(i),

Subsection 725.02(j))

Resubmittal of shrinkage qualification testing Unlimited

Accelerating admixture source

(Subsection 725.02(i),

Subsection 725.02(j))

No qualification testing required Unlimited

ASR mitigating admixture

source and dosage decrease

(Subsection 725.02(k))

Resubmittal of ASR qualification testing Unlimited

All other admixture source and

dosage changes (Subsection

725.02)

No qualification testing required Unlimited

All changes will require administrative submittal to establish proposed changes. Where required, resubmittal testing shall be

completed using the same material sources and proportions from the original approved mix design.

501

No new materials shall be incorporated without prior written approval of the Engineer. In no case shall

concrete from more than one mix design be permitted to be used during the same pour without prior written

approval of the Engineer.

The approved mix design will be allowed consecutive re-approval if no material proportioning or material

sources have changed from the previous year’s approved mix design and the mix design is submitted with

updated aggregate properties and volumes adjusted accordingly. The aggregate properties shall be tested

annually. Aggregate property values will be valid for 14 months from the date tested. The properties to be

tested include, but are not limited to, specific gravity and absorption.

The mix design shall be accompanied by the previously completed and accepted mix qualification test data

and any applicable updated test information. The submittal shall also include all applicable quality control

test results and all requests for variance from the material requirements of these specifications.

501.04BATCHING

batch plant. Batch plants shall have an inspection completed prior to the first concrete placement

on an Agency project if it has been more than 12 calendar months since the last inspection.

Requests for inspection and required documentation shall be received by the Agency’s Materials

Testing and Certification Section a minimum of 21 calendar days prior to the date of the requested

inspection.

All deficiencies shall be corrected and verified a minimum of 5 calendar days prior to the first

concrete placement for any Agency project. The batch plant shall meet the requirements of

AASHTO M 157, except as modified in these specifications, and shall always be maintained in

good repair. The batch plant shall be subject to periodic inspections by authorized representatives

of the Agency. The batch plant shall have approved methods of storing, measuring, and dispensing

approved admixtures.

All concrete batch plants offered for Agency approval shall be equipped for semi-automatic

batching and proportioning of all cementitious material, aggregates, water, and for the automatic

insertion of admixtures. The plants shall be equipped to automatically and accurately record and

report batch weights.

Proper facilities shall be provided for the Engineer to inspect ingredients and processes used in the

batching and delivery of the concrete. The Contractor shall, without charge, afford the Engineer

all reasonable facilities for securing samples to determine whether the concrete is being furnished

in accordance with these specifications. In the batch room area, the producer shall provide the

inspector with a 24 inch × 18 inch horizontal working surface, at a sufficient working height, with

a seat and an adequate view of the batching controls, display, and power supply.

501

The Contractor shall give the Engineer 24-hours’ notice of intent to place concrete. Failure to give

notice which causes postponement of placing operations shall not be reason for determining an

extension of Contract time per the requirements of Subsection 108.11.

Materials on the batch weight ticket shall be identified by type. All batch weight ticket information

shall be provided in English units. All materials added to the concrete batch shall be added to the

batch weight ticket prior to delivery.

controller shall start the weighing operation of the materials and stop the flow automatically when

the designated weight has been reached. It shall be interlocked to ensure that the discharge

mechanism cannot be opened until the weight is within the tolerance specified in Subsection

Water and admixtures may be batched in a weigh batcher or by volume in a volumetric device.

When actuated, volumetric controls shall start the measuring operation and stop the flow

automatically when the designated volume has been reached.

for the use of Agency personnel as a testing laboratory. The Contractor shall attain and maintain a

qualified laboratory status in accordance with the current edition of the Agency’s Qualified

Laboratory Program. Failure to comply with this program may result in suspension of material

production for Agency projects.

501

The testing laboratory shall have a minimum gross internal area of 150 square feet with a layout

providing a minimum internal width of 7 feet, in which to house and use the equipment specified.

Should the Contractor elect to provide additional equipment relevant to testing of Portland cement

concrete and materials, the gross inside floor area of the laboratory shall be increased in proportion

to the area required to house and operate the additional equipment. If the additional equipment is

to be operated on a bench, the length of bench sections shall also be proportionally increased.

Adequate ventilation, lighting, heating, and any necessary electrical or gas connections shall be

provided. Proper sanitary toilet facilities with a lavatory shall be available for use by Agency

personnel at the plant site. Dedicated private telephone and internet services shall be provided to

the laboratory in accordance with Subsection 631.02(a)(4), except that selection of the service by

the Engineer is not required.

The laboratory shall be equipped with the following items and equipment:

1 Standard office desk, with lockable drawers or a separate lockable two-drawer file cabinet and

chair

1 Agency Qualified Laboratory Binder with producer equipment calibration data

1 Set of bench sections at least 2 feet wide providing a minimum of 28 square feet of working

area with under-counter shelving

1 Standard laboratory stool

1 Electronic calculator with eight digit capacity

1 Standard laboratory sink and faucet provided with an adequate supply of water meeting the

requirements of Subsection 745.01. The sink shall drain to the outside of the laboratory.

1 Bench brush

1 Floor brush

1 Motorized 8-inch sieve shaker with an adjustable timer. The shaker’s operation shall be

conducted by means of lateral and vertical motion of the sieve accompanied by jarring action

with the following 8-inch diameter sieves: 3/8 inch (9.50 mm), No. 4 (4.75 mm), No. 8 (2.36

mm), No. 16 (1.18 mm), No. 30 (0.600 mm), No. 50 (0.300 mm), No. 100 (0.150 mm), plus

pan and cover.

501

1 Mechanical aggregate shaker with an adjustable timer, a 1 cubic foot capacity, together with

the following screens: 1-3/4 inch (43.0 mm), 1-1/2 inch (37.5 mm), 1 inch (25. 0 mm), 3/4 inch

(19.0 mm), 1/2 inch (12.5 mm), 3/8 inch (9.50 mm), 1/4 inch (6.30 mm), No. 4 (4.75 mm), No.

8 (2.36 mm), No. 16 (1.18 mm), and pan. The aggregate shaker may be placed in a separate

enclosed area or be shielded for dust and sound control. When the aggregate shaker is placed

in a separate enclosed area, there shall be a minimum of 5 feet of clear space measured from

the front frame of the aggregate shaker outward, as well as a bench section measuring

approximately 36 inches high, 24 inches deep, and 50 inches long located adjacent to the

aggregate shaker. The area shall be well lit and ventilated.

1 Square pointed shovel

5 Five gallon plastic buckets, with handles

1 Electronic balance with a minimum capacity of 50 pounds and accurate to 0.0002 pounds. If

separate fine and coarse aggregate scales are to be used, the fine aggregate scale shall meet the

requirements of AASHTO M 231, Table 2, Class G2 with a minimum capacity of 1.75 pounds

and readable to 0.0002 pounds. The coarse aggregate scale shall meet the requirements of

AASHTO M 231, Table 2, Class G5 with a minimum capacity of 50 pounds and readable to

0.002 pounds.

1 Set of standard masses (weights) to use for verifying the accuracy of the electronic balance

2 Double-burner hot plates with variable temperature controls

3 Metal pans with a nominal size of 9 inches × 9 inches × 2 inches

5 Metal pans with a nominal size of 9 inches × 13 inches × 2 inches

1 Sample splitter with a 2-1/2-inch chute

1 10-inch blunted trowel

1 4 foot × 4 foot minimum heavy canvas for quartering samples

1 Brass wire-bristle brush

1 Pair of heat-resistant gloves (500°F, short-contact)

2 1-1/2 inch soft bristle paint brushes

501

Acceptable substitutes for these items and equipment may be made with the approval of the

Structural Concrete Engineer.

Batching operations shall not begin until the testing laboratory has been approved as being in

compliance with these specifications and all equipment and equipment calibration requirements of

the Agency’s Quality Assurance Program and Qualified Laboratory Program documents.

Removal of any equipment, except upon written request and with the written approval of the

Structural Concrete Engineer, will revoke any prior approvals or qualifications and require the

termination of batching operations.

The building or room designated as a testing laboratory shall be maintained in a clean condition

by the producer and kept free of all articles not necessary for the testing of materials. Cleaning

supplies shall be furnished by the Contractor.

separate compartments for fine aggregate and for each required separate size of coarse aggregate.

If cement is used in bulk, a bin, hopper, and scale for cement shall be included. Each compartment

shall be designed to discharge efficiently and freely into the weighing hopper or hoppers. Means

of control shall be provided so that when required, the material may be added slowly in minute

quantities and shut off with precision.

Hoppers shall be constructed to eliminate accumulations of tare materials and to discharge fully

without jarring the scales. Partitions between compartments shall be configured to prevent spilling

under any working condition. All batch plant structures shall be properly leveled and maintained

in that condition within the tolerance required by the design of the weighing mechanism.

The scales for determining the mass (weight) of aggregate, water and cementitious material shall

be comprised of a suitable system of levers or load cells. The levers or load cells shall determine

the mass (weight) consistently within 0.5% under operating conditions, with loads indicated either

by means of a beam with balance indicator, a full-reading dial, or a digital read-out or display.

Adequate means for checking the accuracy of the scales shall be provided by the Contractor either

using 50 pound weights or by other methods approved by the Structural Concrete Engineer.

Weights shall be certified annually by the Weights and Measures Section of the Vermont Agency

of Agriculture, Food, and Markets. All exposed fulcrums, clevises, and similar working parts of

scales shall be kept clean.

501

When beam-type scales are used, provision shall be made for indicating to the operator that the

required load in the weighing hopper is being approached. Poises shall be designed to be locked

in any position to prevent unauthorized change of position. All measuring and weighing indicating

devices shall be in full view of the operator while charging the hopper and the operator shall have

convenient access to all controls.

The scales shall be serviced and their accuracy verified annually by a hopper-scale service person

licensed by the Weights and Measures Section. For Vermont plants, an inspector representing the

Weights and Measures Section shall witness all testing conducted by the service person and will

attach a seal to each hopper scale, provided it meets the current specifications, tolerances, and

regulations adopted by the Weights and Measures Section. Standard test weights used to determine

the accuracy of hopper scales shall be certified yearly by the Weights and Measures Section in

accordance with their established standards.

The ready-mixed concrete producer shall hire a licensed hopper scale service person for annual

checking and service of scales. In addition, Vermont producers shall schedule an inspection with

the Weights and Measures Section between February 16 th and April 30 th of each year, inclusive.

After April 30 th , Vermont plants without current seals affixed to the hopper scales will not be

permitted to supply concrete to Agency projects, unless otherwise directed by the Engineer or until

the seals are affixed.

Out-of-state concrete producers shall observe all annual hopper scale weighing and seal

requirements of their respective states.

determined by a comparison between the desired weight and the actual scale reading. For

volumetric measurement of water and admixtures, accuracy is determined by checking the quantity

either by weight on a scale or by volume in a calibrated container.

Admixture-dispensing systems shall, at a minimum, be annually calibrated by an admixture

distributor representative. The admixture distributor representative shall check at least two

volumes, with a check done at approximately 15% of the minimum and at 15% of the maximum

manufacturer’s recommended dosage range, or other targets as approved by the Structural

Concrete Engineer.

Batching shall be conducted to accurately measure the desired quantities of materials within the

tolerances specified in Table 501.04A.

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TABLE 501.04A – CONCRETE PRODUCTION TOLERANCES FOR BATCHING

Material Tolerance

Cement ± 1%

Water ± 1%

Aggregates ± 2%

Chemical admixtures ± 3%

Mineral admixtures + 10%, - 1%

cement shall be used in a batch of concrete unless the cement is weighed.

All bulk cement shall be weighed on an approved weighing device. The bulk cement

weighing hopper shall be properly sealed and vented to preclude dusting during operation.

Facilities shall be provided for the sampling of cement at the batch plant, either from the

storage silo or from the weighing hopper. The sampling device shall provide a sample that

represents the true nature of the material being used. This device shall be a permanent

installation located to allow for safe and easy access.

meter, the water meter shall be so located that the measurements will not be affected by

variable pressures and temperatures in the water supply line.

Measuring tanks shall be equipped with an outside tap and valve to provide for checking

the setting, unless other means are provided for readily and accurately determining the

amount of water in the tanks.

All water metering methods shall be verified and calibrated on an annual basis or at any

time there is a question of accuracy. All water added to the concrete at any point shall be

through an approved metering method.

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contamination from underlying material and accumulation of excessive moisture.

Aggregates from different sources or of different gradations shall not be stockpiled

together. Only rubber-tired equipment shall be permitted to operate on aggregate

stockpiles.

Stockpiles shall be constructed as follows:

bucket, rock ladder, radial stacker, or other approved equipment), the stockpile shall

be made in such a manner that segregation is kept to a minimum.

shall be approximately 4 feet in depth. Each layer shall be completely in place

before commencing the next layer. Care shall be taken that successive layers do not

cone down over the previous layer.

to deposit the material for the layer being placed. It shall be the responsibility of

the Contractor to ensure that the aggregate is kept free from deleterious material or

degradation.

Stockpiles shall be maintained in such a manner that twice the anticipated aggregate

requirement for any Agency project placements will be on hand and available for

sampling and testing at least 48 hours before mixing operations for the placements

are scheduled to begin. The Engineer may modify this requirement when special

aggregates are required.

Aggregates shall be handled from stockpiles or other sources to the batch plant in

such a manner as to secure a uniform grading of the material. Aggregates that have

become segregated or mixed with earth or foreign material shall not be used. All

aggregates, except lightweight coarse aggregate, produced or handled by hydraulic

methods, and washed aggregates, shall be stockpiled or binned for draining at least

12 hours before being batched. In case the aggregates have a high or non-uniform

moisture content, a storage or stockpile period longer than 12 hours may be required

by the Engineer.

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Stockpiles being watered per the specifications or allowed through producer QC

procedures shall be watered for a sufficient time to ensure consistent moisture

throughout the stockpile. Aggregate stockpiles being watered shall be loaded in the

bin within 1 hour of being batched.

The Contractor shall conduct moisture content tests within 1.5 hours of the

anticipated concrete batching time. If there is a visual difference in aggregate

moisture appearance, aggregate moisture content will be tested again and new

moisture test results shall be obtained and used as soon as possible. Material that

has been stored in a storage bin for more than 10 hours shall be retested for moisture

content. A minimum of one cubic yard of aggregate will be removed from the

bottom of the storage bin and discarded. A minimum of one cubic yard of aggregate

will then be removed and a moisture content sample taken.

Plants that employ moisture probes shall have them calibrated and verified a

minimum of 24 hours prior to batching or as directed by the Structural Concrete

Engineer. The procedure for checking the meter will be to run aggregate over the

probe and then collect a portion of the aggregate on which to perform a moisture

content test. If the difference between the meter and the tested moisture content is

greater than 0.5%, then the meter shall be calibrated.

of time to ensure that the aggregate is completely saturated surface dry or greater

immediately prior to use as indicated by moisture testing. Soaking shall be

accomplished by continuous sprinkling or other suitable means that will provide a

uniform moisture content throughout the stockpile. The stockpile shall be allowed

to drain for 12 hours to 15 hours immediately prior to use.

amounts of admixtures to each batch. Admixtures shall be dispensed in such a manner that

will ensure uniform distribution of the material throughout the batch within the required

mixing period. Except as specified herein, all admixtures shall be added to the batch at the

plant, unless otherwise authorized by the Structural Concrete Engineer.

Chemical admixture containers, metering equipment, and scales shall be calibrated

annually by a qualified admixture distributor representative. Admixture calibration and

verification shall be done at 15% of the high, at approximately the middle, and at 15% of

the low recommended ranges for the admixture being dispensed by the system. The

calibration and verification shall be done in the presence of an Agency representative when

requested by the Agency.

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All dispensers shall include visual inspection aids such as graduated transparent cylinders.

A separate dispenser shall be provided for each liquid admixture. If the dispensing system

does not provide visual inspection aids, then periodic verification tests shall be done at a

frequency satisfactory to the Structural Concrete Engineer. Calibration and verification

records shall be kept at the production facility for a minimum of one year. The producer

shall perform the calibration and verification of the metering systems when requested.

Storage and dispensing systems for liquid admixtures shall be equipped to allow thorough

circulation and agitation of all liquid in the system. This shall be required prior to the first

batching of concrete for Agency projects in any calendar year and periodically thereafter

at intervals not to exceed 60 calendar days for the duration of the period the plant is

supplying concrete for Agency projects.

If the plant has received a delivery of at least 25% of the volume of the storage container,

this will be considered as a method of circulation or agitation. If the circulation method is

used, the admixture shall be circulated until a complete exchange of admixture is achieved.

If an agitation method is used, the method shall be subject to approval by the Structural

Concrete Engineer. If an admixture does not need agitation, then the admixture

manufacturer shall submit a written statement annually indicating that agitation is not

required.

Storage and dispensing systems for liquid admixtures shall be maintained within the

manufacturer’s stated temperature and environmental conditions.

It shall be the responsibility of the Contractor to use the quantity of Agency-approved

admixtures needed to obtain concrete meeting the requirements of the Contract. All

admixtures shall be approved by the Structural Concrete Engineer prior to incorporation

into the mix.

content.

admixtures, accelerators and specialty admixtures shall be in the recommended

range as stated by the manufacturer, unless otherwise approved by the

manufacturer.

or holding bins or other approved holding containers and shall be protected from rain and

moisture.

501

501.05MIXING AND DELIVERY

wholly or in part in transit mixers. The production of concrete shall meet the requirements of

AASHTO M 157 with the following additional requirements:

cement has been added to the water. When an approved admixture to slow or temporarily

halt the hydration process of the cement is used, this time limit will be extended to 2 hours,

provided the mix has adequate workability. Prior to discharge, the Contractor shall perform

concrete temperature testing on every load of concrete which will be deposited after the

1.5 hour time limit, as defined above, to verify the concrete temperature is within the limits

defined by Subsection 501.07.

A time limit greater than 2 hours may be approved if the request is made a minimum of 3

working days prior to the placement and all quality control test results are within

specification immediately prior to placement. The request to extend the time limit beyond

2 hours shall include the requested time limit and required admixture dosages. Acceptance

testing will be performed by the Engineer, concrete will not be accepted on the basis of

quality control tests performed by the Contractor.

Concrete shall not have water added once discharging has begun. Admixtures may be

adjusted as required by the producer before discharge has begun. Admixtures to slow or

temporarily halt the hydration process of the cement shall only be added at the production

facility.

If, in the opinion of the Engineer, any concrete appears to have visually changed from

previously placed concrete, the Contractor shall perform quality control tests to confirm

the concrete conforms to the specifications.

shall be present on the project to determine the final admixture dosage and water addition

for each load of concrete. The dosage shall be applied by means of a dispenser, or by other

means of accurately measuring volume as approved by the Engineer. The Contractor shall

provide QC concrete testing personnel, with current ACI Concrete Field Testing

Technician Grade I Certification, to confirm the concrete is within specifications for the

required work.

501

inspection personnel. If additional mixing water, admixtures, or other additions are

required, a minimum of 30 revolutions of the mixer drum at mixing speed shall be required

before discharge of any concrete. If water is added in excess of the specified maximum

W/CM ratio, the concrete shall not be used.

agitator, in accordance with AASHTO M 157 and reported except as modified below. Two

samples shall be taken. The first sample shall be taken after 15% of the load volume has

been discharged, and the second prior to 85% of the load volume being discharged.

Slump and air content tests shall be performed on each sample. The maximum difference

in air content between the two samples shall be 1%. For concretes with a specified slump

of 4 inches or less, the maximum difference between the two samples shall be 1 inch. For

concretes with a specified slump greater than 4 inches, the maximum difference shall be 1-

1/2 inches. If both conditions are not met, then the Contractor will be required to either

modify the mixing procedure or batching sequence, or that transit mixer or agitator will not

be allowed to deliver concrete to the project. The Contractor will be required to perform

uniformity tests to confirm the changes have satisfactory results.

ticket meeting the requirements of Subsection 501.04(b).

batch plant that shall be available to the Engineer at all times during concrete operations.

The cost of this service will be considered incidental to the work.

blades, not including initial mixing revolutions. The total allowed number of revolutions

may be increased as directed by the Engineer.

Mortar shall be mixed in an approved mixer at the site of placement or in transit mixers when

approved by the Engineer. The Engineer will withdraw approval for use of transit mixers, if

necessary, to ensure a quality product or if the rate of delivery cannot be coordinated with finishing

requirements.

mixing time for mixers that have a capacity of 10 cubic yards or less shall be not less than 90

seconds. For mixers that have a capacity of more than 10 cubic yards, the mixing time shall be

determined by the concrete producer.

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The time is valid provided that mixer efficiency tests prove the concrete is satisfactory for

uniformity and strength. The plant shall be equipped with a timing device that will not permit the

batch to be discharged before the predetermined mixing time has elapsed. Vehicles used in hauling

shall comply with the requirements of Subsection 501.05(c).

authorized representative of the Agency. Such equipment shall bear a currently dated inspection

sticker supplied by the Agency indicating that the transit mixer or agitator conforms to the

Agency’s requirements.

For the purpose of this specification, the term agitator shall be interpreted to mean a vehicle with

a drum that is not used to perform the initial mixing of the concrete but is used to transport the

concrete and mix the concrete prior to discharge.

Transit mixers shall be equipped with a water-measuring tank with a visible sight gauge for use

when the water for the batch is supplied from the transit mixer tank. The gauge shall be clean and

legibly graduated. Measuring tanks shall be provided with outside drain valves or other means to

check their calibration. These should be easily opened for checking at any time.

Electrically actuated revolution counters shall be required on all transit mixers except on mixers

charged at central mix plants and used as agitator trucks only.

All mechanical details of the mixer or agitator such as water measuring and discharge apparatus,

condition of the blades, speed of rotation of the drum, general mechanical condition of the unit

and clearance of the drum shall be checked before a further attempt to use the unit will be

permitted.

Mixers and agitators shall be kept free from accumulation of hardened concrete or mortar. The

mixing blades shall be rebuilt or replaced when any part or section is worn 3/4 of an inch or more

below the original height of the manufacturer’s design. A copy of the manufacturer’s design,

showing the dimensions and arrangements of blades shall be available to the Engineer at the plant

at all times.

Concrete containing silica fume shall be mixed in accordance with the appropriate situation:

shall be mixed for not less than 125 revolutions of the drum or blades at the rate of rotation

designated by the manufacturer of the equipment as the mixing speed. The mixing and

agitating speeds shall be found on the metal plate on the mixer.

501

admixture at the cement plant prior to being delivered to the concrete plant, each batch of

concrete shall be mixed for not less than 70 nor more than 100 revolutions of the drum or

blades at the rate of rotation designated by the manufacturer of the equipment as the mixing

speed. The mixing and agitating speeds shall be found on the metal plate on the mixer. If

inconsistent test results are obtained, or the batch of concrete appears not to be completely

mixed, the mixing revolutions shall be extended as necessary.

When a transit mixer or agitator is used for transporting concrete, mixing during transport shall be

continuous and at two to six rotations per minute or as designated by the manufacturer of the

equipment as agitating speed. Failure to do so will be cause for rejection of the concrete.

Transit mixers and agitators assigned to a project shall not be used for other purposes until the

desired work is completed at the site and shall arrive at the project within the cycle that anticipated

placement conditions dictate. The interval between loads shall be controlled such that concrete in

place shall not become partially hardened prior to placing succeeding batches. The plant capacity

and transportation facilities shall be sufficient to ensure continuous delivery at the rate required.

Before discharging concrete from a transit mixer that has been operating at agitating speed, the

drum or blades shall be rotated approximately one minute at mixing speed. The same procedure

shall apply to agitators.

Upon discharge of the concrete from the drum, a sufficient amount of water shall be charged into

the drum to properly cleanse the drum. This water shall not be used as a part of the next succeeding

batch but shall be discharged from the drum prior to the charging of the drum with the concrete

ingredients. The drum shall be completely emptied before receiving materials for the succeeding

batch. Re-tempering of concrete or mortar that has partially hardened, by remixing with or without

additional materials, shall not be permitted.

501.06QUALITY CONTROL. The Contractor shall provide assistance, equipment, materials, and

curing for field sampling and testing as required by the Engineer. All costs shall be included in the Contract

unit prices under Section 631. The Engineer shall perform all acceptance sampling and testing in

accordance with the Agency’s Quality Assurance Program. The Contractor shall perform all on-site

quality control (QC) sampling and testing. The person performing the QC sampling and testing shall have,

as a minimum, current ACI Concrete Field Testing Technician Grade I Certification.

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Engineer, the Engineer may require the Contractor to construct a slab to be used for the trial pour.

The purpose of the trial pour is to ensure that the mix can be placed and finished in accordance

with these specifications. The concrete slab shall be 10 feet × 10 feet × 9 inches thick, unless

otherwise directed by the Engineer.

If the concrete is intended to be placed by pump, the trial pour concrete shall be placed by pump.

The pump will be set up in the configuration that best represents the most difficult pumping

condition. The wet concrete properties will be checked at the point of placement. The Contractor

will demonstrate that they can provide an acceptable finish to the concrete for the element to be

completed. The Contractor will need to bull float a minimum of 50% of the surface area of the slab

and hand finish the curb areas in the same manner as anticipated during the production pour.

The Contractor may elect to construct the slab so that the same screed equipment and same

finishing method can be used as anticipated for the production pour. In this case the Contractor

will not be required to bull float a minimum percentage of surface area unless that will be included

in their process for finishing the concrete deck surface during the deck pour. The test slab will

become the property of the Contractor and removed from the project after completion of the trial

pour.

Concrete production activities shall be closely monitored to ensure that no deviations are made

from the approved mix design. If test results indicate a failure to obtain the characteristics as

specified in Table 501.03A, the Engineer may reject the material. The Contractor will be

responsible for proposing solutions which could include changes to the mix design and will require

testing be done with no extra payment. The modified mix design shall not be used until successful

test results are obtained during a trial pour that is representative of the anticipated pour conditions.

or other procedures approved by the Agency. Sampling will be done at the point of placement or

as close to it as practical.

tolerances, whether modified at the batch plant or at the site, additional QC sampling and

testing shall be performed on the modified load prior to incorporating the concrete into the

work.

501

purposes that is taken before 15% of the load has been discharged. Beginning of load

sampling shall be performed as required by the Engineer, or as needed to ensure that the

concrete meets the Contract requirements at the point of placement. The QC personnel

shall monitor the placement operation and adjust the mix accordingly to ensure that the

material being incorporated into the work meets Contract requirements.

C1611, Procedure B. The concrete inside the cone shall not be tamped.

accordance with ASTM C1611, Appendix X.1 and shall be performed on each completed spread

test.

in AASHTO T 152.

For Class SCC concrete, the specimens shall be fabricated in accordance with ASTM C1758.

will be as specified in the Materials Sampling Manual. The Engineer may order additional

tests as deemed necessary.

Compressive test cylinders shall be made in accordance with the requirements of AASHTO

R 100 and tested for compressive strength in accordance with the requirements of AASHTO

T 22.

For Class SCC concrete, the specimens shall be fabricated in accordance with ASTM

C1758.

compliance with requirements for the project. All test cylinders used for quality

acceptance testing shall be stored in an approved curing box until they are shipped

to the Agency’s Materials Testing and Certification Section Central Laboratory.

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adequate curing procedures are being followed and for early form removal or early

loading of structure.

the same curing and protection from the elements as the concrete that they

represent up until 24 hours before anticipated testing of specimens.

testing for estimating the concrete strength. The procedures of ASTM C1074

shall be followed for the maturity method except as noted below:

cylinders cast. Two of the 17 shall have temperature sensors

embedded in them to be used for monitoring.

ii. For ASTM C1074, Section 8.4 there shall be 3 cylinders tested for

each test age.

iii. For ASTM C1074, Section 8.4 for rapid set concrete mixes the test

ages shall be 12 hours, 1 day, 2 days, 7 days, and 28 days. The

Contractor may adjust or add test ages if approved by the Engineer.

All temperature measuring devices shall be verified or calibrated on a 12

month basis or sooner if there are questions about their accuracy. The

devices shall have an accuracy of ± 2 o F.

At least two temperature sensors shall be embedded each day in each pour.

One sensor shall be placed where maturity is expected to develop the

slowest at, or near, an exposed outer edge, and a second sensor shall be

placed in the concrete poured from the last load of the day. Sensors shall be

placed 2 inches to 4 inches from any existing concrete or an exposed outer

edge. The temperature sensing end of the monitor shall not be placed in

direct contact with reinforcing materials or other elements that will protrude

through the surface of the concrete. The Contractor shall submit the

proposed locations to the Engineer for review and approval.

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in the specifications or as directed by the Engineer. If not specifically stated, the

curing shall be as specified in Table 501.06A.

TABLE 501.06A – CONCRETE SPECIMEN CURING REQUIREMENTS

Testing Category Number of Specimens Curing Location

Acceptance See the Materials

Sampling Manual Curing box

Job control 2 per test On structure

requirements of ASTM C1064.

501.07WEATHER AND TEMPERATURE LIMITATIONS. The temperature of the concrete just prior

to placement in the forms shall not be less than 50°F nor more than 85°F. Aggregates and water shall be

heated or cooled as necessary to produce concrete within these temperature limits.

Placement and curing procedures shall be approved by the Engineer prior to actual placement.

based on an assessment of temperature, humidity, wind velocity, and sun radiation conditions. No

concrete shall be placed when the ambient air temperature is, or is expected to be, above 90°F.

the ambient air temperature is expected to be below freezing at any point or below 40°F

for a continuous 8-hour period. No concrete shall be placed when the ambient air

temperature is lower than 10°F except by written permission of the Engineer. A cold

weather concrete plan shall be submitted to the Engineer for their review and acceptance

before any cold weather concrete is placed.

When placing cold weather concrete, the Contractor shall have adequate equipment for

heating and protecting the materials and freshly placed concrete meeting the approval of

the Engineer. This equipment shall be on the job and ready to deploy prior to the

commencement of concrete placing operations.

No concrete shall be placed in any superstructure or thin section under cold weather

conditions.

501

placement shall be capable of heating the materials uniformly. Aggregates shall not be

heated to a temperature exceeding 150°F. If water is heated to a temperature exceeding

140°F, the water shall be mixed with the aggregate before the cementitious material is

added.

The materials shall be heated in such a manner, for such a period of time, and in such

quantity, as to produce concrete having a uniform temperature within the specified

temperature range at the time of placement. Materials containing frost or frozen lumps shall

not be used.

Stockpiled aggregates may be heated using dry heat or steam. Aggregates shall not be

heated directly by gas or oil flame, or on sheet metal over a fire. When aggregates are

heated in bins, steam-coil or water-coil heating, or other methods that will not be

detrimental to the aggregates, may be used.

mix to lower the freezing point of the concrete.

removed from the forms.

Concrete shall not be placed on any surface or in any forms that are frozen, have surface

temperatures below 32°F, or that contain frozen materials. The frozen surface or forms

shall be completely thawed the day before the placement of the concrete and shall be kept

continuously thawed until the concrete is poured. The temperature difference between

forms or substrate and the plastic concrete shall not exceed 40°F.

other suitable type of housing to fully enclose and protect the structure when placing and

curing cold weather concrete. The sidewalls and roofing of the protective housing shall be

completely built before the placing of any concrete.

The protective housing shall be constructed independently of the forms and bracing and

with adequate space to allow for form removal and the initial finishing of the concrete as

required during the heating period. Joists shall be located to suitably support the housing

roof with no sagging. The protective enclosure shall be heated to the proper temperature

before placing any concrete.

501

When the temperature readings taken on or in the concrete indicate the temperature of the

concrete may fall below 50°F, the Contractor shall, without exposing the concrete,

immediately build the necessary enclosures around the area involved and supply heat to

ensure curing conditions as specified in Subsection 501.15. The enclosure shall be removed

when directed by the Engineer.

of the concrete and the enclosed air shall be kept above 50°F, and not more than 40°F above

the internal concrete temperature, for the designated curing period. During this time, the

concrete shall be kept continuously wet to provide proper curing. The internal concrete

temperature shall not exceed 160°F. After the curing period, the temperature shall be

gradually lowered to that of the surrounding atmosphere, taking at least 48 hours for the

transition but at no time exceeding a 1°F change per hour.

When dry heat is used, a means of maintaining atmospheric moisture shall be supplied.

The Contractor shall also maintain adequate fire protection and shall provide personnel to

keep the heating units in continuous operation. When concrete placement operations are in

locations where water levels may fluctuate, the supports for heating equipment shall be

built so that the heating equipment can be raised, and steam lines shall be placed above the

probable high water level.

The enclosure shall be well-ventilated to avoid accumulation of carbon dioxide and carbon

monoxide.

When using a hydronic heating system with heat-transfer fluid that circulates through a

series of hoses, the heat-transfer hoses shall be laid on top of the vapor barrier, usually

plastic sheeting, then covered with approved insulating materials or by other approved

methods for retaining heat.

continuously record concrete curing temperatures and ambient air temperatures for the

entire curing period. Recording thermometers shall be capable of measuring and recording

temperatures within the range of 0°F to 200°F with maximum graduations of 5°F.

Temperature sensors shall be carefully placed within the curing enclosure or in the concrete

to ensure that temperatures are measured at typical locations. Concrete temperature sensors

shall be embedded between 2 inches and 3 inches into the concrete or as directed by the

Engineer. The recorder’s accuracy shall be certified once every 12 months, with the

certificate displayed with each recorder. The Engineer may make random checks of each

recorder.

501

On each recorder chart or file, the Contractor shall indicate the location of the

representative concrete, the placement date, and start and finish times of the temperature

record. At the completion of the curing period, the recorder charts shall be submitted to the

Engineer.

A thermometer shall be provided that is capable of displaying the current ambient

temperature with a maximum gradation of 1°F. The inspector will use the thermometer to

take periodic temperature measurements of the enclosure at varying locations.

The Contractor shall provide a hand-held infrared thermometer capable of taking no-

contact measurements that is accurate within plus or minus 2% of the reading. The

thermometer’s accuracy shall be certified once every 12 months, with the certificate

provided with each thermometer.

When the Contractor places concrete at more than one location within the specified curing

period or if the Engineer determines that monitoring of a single pour is necessary in

multiple locations, additional monitoring and recording equipment shall be furnished to

provide temperature records at each location.

501.08FORMS. The Contractor shall be responsible for, and shall make good, any injury arising from

inadequate forms. The Engineer shall be provided with the opportunity to inspect all forms prior to

concrete placement.

Unless the Plans specifically allow for the use of stay-in-place forms, such forms shall not be used in the

construction of any superstructure or bridge deck. Stay-in-place forms will only be allowed as approved

by the Engineer.

by falsework piling. The Engineer may require the Contractor to employ screw jacks or hardwood

wedges to correct any deflections or settlement, however slight, occurring in the falsework.

pressure of the concrete and other loads incidental to the construction operations, including

vibration. Forms shall be constructed and maintained to prevent the opening of joints due to

shrinkage of the lumber. Sealers and caulking as approved by the Engineer shall be used where

forms abut structural steel members, such as top flanges of beams and girders.

To ensure their easy removal, forms shall be filleted and chamfered at all sharp corners, unless

otherwise shown on the Plans or directed by the Engineer, and shall be given a bevel or draft in

the case of all projections, such as girders and copings.

501

Falsework and forms for slabs, beams, and girders shall be constructed to provide the camber

shown on the Plans or ordered by the Engineer.

Falsework and forms for Class SCC concrete construction shall be designed with consideration

given to concrete placement rates, mix temperature, additives, and placement procedures that

affect hydrostatic pressure of the concrete. Forms shall be water-tight and sufficiently rigid to

prevent distortion due to the pressure of the concrete and other loads incidental to the construction

operations, including vibration.

plywood, not less than five ply and with a minimum thickness of 3/4 inch. In computing stud

spacing, plywood shall be considered 1 inch lumber, provided that the grain of three of the plies

runs perpendicular to the studs.

Form lumber for unexposed surfaces may be dressed tongue-and-groove, dressed shiplap, or

square-edge surfaced four sides of uniform width and thickness, with a minimum thickness, after

finishing, of 3/4 inch.

All form lumber shall be sound and free from loose or rotten knots, knotholes, checks, splits, or

wanes showing on the surface that will be in contact with the concrete. Used face form lumber,

having defects or patches which may produce work inferior to that resulting from new material,

shall not be used.

Other form materials may be used with the permission of the Engineer.

to a depth of at least 1 inch from the face without injury to the concrete. Wire ties shall be used

only in locations where they will not extend through surfaces exposed in the finished work and

then only when authorized by the Engineer.

Unless otherwise specified, cavities shall be filled with a product that meets the requirements of

Subsection 780.01. The manufacturer’s recommendations shall be followed for surface

preparation, mixing, application, and curing.

reinforcement, and wood forms shall be saturated with water immediately before placing the

concrete. Any material that will adhere to or discolor the concrete shall not be used.

chamfered corners, beveled projections, bracing, alignment, removal, reuse, and oiling also apply

to metal forms. The metal used for forms shall be of such thickness that the forms will remain true

to shape throughout the concrete placement operations.

501

All bolt and rivet heads shall be countersunk. Clamps, pins, or other connecting devices shall be

designed to hold the forms rigidly together and to allow removal without injury to the concrete.

Metal forms that do not present a smooth surface or do not line up properly shall not be used. Care

shall be exercised to keep metal forms free from rust, grease, or other foreign matter.

be removed before the end of the cure period for the deck specified in Table 501.15A.

Forms under beams or floor slabs may be removed upon approval of the Engineer after the

concrete attains 85% of the minimum compressive strength as specified in Table 501.03A,

but not prior to the end of the cure period specified in Table 501.15A.

removed before the end of the cure period specified in Table 501.15A unless otherwise

approved by the Engineer. Removal of forms prior to the end of the cure period will only

be allowed if a vertical surface curing plan has been approved by the Engineer. Forms

under arches, pier caps, or other special design conditions may be removed upon approval

of the Engineer after the concrete attains 85% of the minimum compressive strength as

specified in Table 501.03A, but not prior to the end of the cure period specified in Table

501.15A

Methods of form removal likely to cause overstressing of the concrete shall not be used.

Forms and their supports shall not be removed without approval of the Engineer. Supports

shall be removed in such a manner as to permit the concrete to uniformly and gradually

take up the stresses due to its own dead load.

construction shall be subject to the following requirements:

concrete with a flat-surfaced finish.

made with removable forms.

maintain the deck thicknesses shown on the Plans.

501

to the form flute (also referred to as the form valley).

concrete, and 55 pounds per square foot for construction loads.

strength of the material.

inch, whichever is less.

North American Specification for the Design of Cold-Formed Steel Structural

Members.

of SIPCMF:

SIPCMF in accordance with the requirements of Subsection 105.06. These

drawings shall contain the following information as a minimum:

girder.

regions.

may be required.

501

supports, and accessory items during handling, shipping, and storage. During

loading, hoisting, and unloading operations, extra precautions and care shall be

taken to prevent damage to ends, corners, and edges of form sheets, supports, and

accessory items.

If the form units and accessories are to be stored prior to installation, they shall not

be placed in contact with the ground and shall be adequately covered or protected

to keep them dry.

Form supports shall be placed in direct contact with the flange of the beam, girder,

stringer, or floor beam. All attachments shall be made by permissible welds, bolts,

clips, or other approved means. The welding of form supports to steel not

considered weldable or to portions of flanges subject to tensile stresses shall not be

permitted. Welds and welding shall be in accordance with the requirements of

Subsection 506.10, with the exception that a 1/8-inch fillet weld will be permitted.

Form sheets shall not be permitted to rest directly on the flanges. They shall be

securely fastened to form supports by self-tapping screws and shall have a

minimum bearing length of 1 inch at each end. Transverse construction joints shall

be located at the bottom of a valley. A 1/4 inch diameter weep hole shall be drilled

at the lower end of each flute or valley.

Screed and pouring runway supports shall not be located directly on the form

sheets, form supports, or reinforcing steel. No loose sheets or miscellaneous

hardware shall be left on the structural slab at the end of the working day.

The corrugated metal sheets shall be fabricated for the placement sequence used,

with the joints between sections of sheets overlapped or securely fastened to

eliminate differential deflections. Any exposed form metal where galvanizing has

been damaged shall be cleaned and repaired to the satisfaction of the Engineer.

the soundness of the concrete deck against the SIPCMF.

but prior to the next slab pour, one panel of the SIPCMF shall be removed from the

most recently completed pour of each span, at a location selected by the Engineer,

to provide visual evidence that the concrete mix or the construction procedures are

obtaining the desired results.

501

If the concrete mix or the construction procedures are varied significantly within a

pour, such as a change in the extent of vibration or change in the workability of the

mix, another section of forming shall be removed to verify that the new procedures

are yielding desirable results.

Engineer will spot-check the underside areas of the steel forms by sounding with a

suitable weight hammer. If honeycomb or voided areas are detected, the SIPCMF

at that location shall be removed for a visual inspection.

inspection of the concrete surface. The amount of sounding and form removal may

be moderated, at the Engineer’s discretion, after a substantial amount of the slab

has been constructed and inspected, if the Contractor’s methods of construction and

results of the inspections as outlined above indicate that sound concrete is being

obtained throughout the slab.

If, after removing a section of form, the concrete is found to be defective, additional

panels shall be removed as directed by the Engineer. All defective concrete shall

be repaired to match the adjacent concrete in section and color to the satisfaction of

the Engineer.

The Contractor shall provide all facilities required for the safe, suitable, and

convenient means of access to the forms for the Engineer’s inspection procedures.

The form sections shall be removed by a metal saw or air-carbon-arc gouging with

minimum damage to the concrete. Cuts shall only be sufficiently deep to sever the

form. Any other method of removal shall be submitted to the Engineer for approval.

Cuts parallel to the corrugations in the forms shall be located on the sloping surface

midway between a crest and valley. Cuts parallel to the supporting beams or girders

shall be made through the supporting angles taking care not to damage the structural

steel beams or girders.

The Contractor will not be required to replace the forms which have been removed.

501

501.09PLACING CONCRETE

operations to properly place, consolidate, and finish the concrete. If, in the opinion of the Engineer,

the Contractor does not have sufficient skilled personnel to handle the concrete properly, the

Engineer may postpone the start of the concreting operations until the Contractor has remedied

this situation.

shall be scheduled by the Contractor to take place at least 7 calendar days before concrete

placement, and prior to the trial pour, if required. Attendees at the pre-placement meeting shall

include, but not be limited to, the Contractor’s project superintendent, the Engineer, the Structural

Concrete Engineer, and the concrete producer.

The Contractor shall provide a placement plan that addresses, but is not limited to, the following

topics:

problems

501

writing by the Engineer. Authorization to place concrete at any other time shall not be given unless

an adequate lighting system is provided prior to beginning the concrete placement operations.

Concrete shall not be placed under adverse environmental conditions that the Engineer determines

will interfere with acceptable placement or finishing operations.

Concrete shall not be placed until the depth and character of the foundation, the apparent adequacy

of the forms and falsework, and the placing of the reinforcing steel have been approved by the

Engineer. The interior of the forms shall be clean of all debris before concrete is placed.

The Contractor shall submit to the Engineer a schedule of batching, delivery, and placement prior

to the beginning of the concreting operations. The Contractor shall comply with the requirements

of Subsection 501.05.

For deck pours, the Contractor shall submit the required retarder schedule to the Engineer a

minimum of 3 working days in advance of the placement. The retarder schedule shall demonstrate

how the Contractor will ensure that concrete will remain plastic until the deck is fully placed. The

retarder schedule shall include considerations for the maximum time between batching and

discharge, duration of the pour, weather, possible delays, and any other factors that may impact

the time to initial set.

Equipment and tools necessary for handling materials and performing all parts of the work shall

meet the approval of the Engineer as to design, capacity, and mechanical condition and shall be on

the site before the work is started. Any equipment, in the judgment of the Engineer, that proves

inadequate to obtain results prescribed shall be improved or new equipment substituted or added.

The Engineer may suspend the pour or reject the pour if the Contractor deviates from the accepted

pour plan which will also include unacceptable delivery rates. The Contractor will not be allowed

compensation due to the pour being suspended or rejected due to the Contractor deviating from

the accepted pour plan or uncontrolled delivery rates.

For simple spans, concrete shall be deposited by beginning at the lower end of the span and

working toward the upper end. For continuous spans, where required by design considerations, the

concrete placing sequence shall be as shown on the Plans.

Concrete shall not be deposited in the forms more than 4 feet from its final position.

The dropping of unconfined concrete more than 5 feet will not be permitted.

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Concrete shall not be deposited in running water.

The rate of placing the concrete shall be so regulated that no excessive stresses are placed on the

forms. Concrete in all decks shall be placed in one continuous operation, unless otherwise

specified.

Concrete shall be placed in continuous horizontal layers, the thickness of which shall not exceed

18 inches, unless otherwise directed by the Engineer. Each succeeding layer shall be placed before

the underlying layer has taken initial set and shall be consolidated in a manner that will eliminate

any line of separation between the layers. When it is necessary, due to any emergency, to place

less than a complete horizontal layer at one operation, such layer shall terminate in a vertical

bulkhead.

After the concrete has taken its initial set, care shall be exercised to avoid jarring the forms or

straining the ends of projecting reinforcing bars.

the prepared surface shall be flooded with water. After removal of all free water, the overlay

material shall be deposited on the damp surface and manipulated to coat the horizontal and vertical

surfaces to be covered. The rate of progress shall be controlled to prevent the drying of previously

deposited materials.

segregation of the materials and the displacement of the reinforcement and shall be approved by

the Engineer. Aluminum chutes, troughs, or pipes will not be permitted.

All chutes, troughs, and pipes shall be kept clean and free of hardened concrete by thoroughly

flushing with water after each run. Open troughs or chutes shall be either made of metal or be

metal-lined and shall extend as nearly as possible to the point of deposit. When the discharge must

be intermittent, a hopper or other device for regulating the discharge shall be provided.

Dropping of unconfined concrete more than 5 feet or depositing a large quantity at any point and

running or working it along the forms will not be permitted.

vibrators, of an approved type and design, operating within the concrete. When required, vibrating

may be supplemented by hand-spading with suitable tools to ensure proper and adequate

consolidation.

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Vibrators shall be manipulated to work the concrete thoroughly around the reinforcement and

imbedded fixtures and into corners and angles of the forms to produce surfaces free of

imperfections. Vibrators shall not be used to cause concrete to flow or run into position in lieu of

placing. The vibration at any point shall be of sufficient duration to accomplish consolidation but

shall not be prolonged to the point where segregation occurs.

Vibrators shall have non-metallic or rubber-coated heads. Vibrating machines shall at no time be

left running unattended in the concrete.

When it is necessary due to an emergency to discontinue the placing of a monolithic section, the

use of vibrators shall cease. Vibrators shall not again be used until a sufficient depth of fresh

concrete is placed to prevent any possibility of the effect of vibration on the concrete already in

place and in no case shall this depth be less than 2 feet.

The number of vibrators used shall be ample to consolidate the incoming concrete immediately

after it is deposited in the form. The Contractor shall have at least one spare vibrator in serviceable

condition at the site of the structure in which more than 25 cubic yards of concrete are to be placed.

The vibrators shall be capable of transmitting vibration to the concrete at frequencies of not less

than 4,500 impulses per minute under load. The vibration shall be of sufficient intensity and

duration to cause plasticity, settlement, and complete consolidation of the concrete without causing

segregation. The vibrator shall visibly affect a mass of concrete of 2-inch slump over a radius of

at least 18 inches.

Unless otherwise specified, Class SCC concrete shall not be consolidated with mechanical

vibrators. If the Engineer requests the use of a vibrator, it shall be of an approved type and design,

operating within the concrete. To avoid segregation of the concrete, it shall be used as little as

possible.

completed prior to the placement of the concrete. Regardless of the above limitation on blasting

operations, the Contractor shall be responsible for any damage resulting from blasting operations.

501.10DEPOSITING CONCRETE UNDER WATER

Contract or upon approval of the Engineer. Class SCC concrete shall be used for all underwater

concrete, unless otherwise approved by the Engineer. An anti-washout admixture shall be added

to the mix design for all underwater concrete. Underwater concrete with an anti-washout admixture

shall have a minimum air content of 3%. The anti-washout admixture may cause a delay in set

times.

501

The anti-washout admixture is not required to be included in mix qualification testing. If the anti-

washout admixture is not included in the mix design for qualification testing, an administrative

submittal with the addition of the anti-washout admixture to an approved mix design shall be

submitted in accordance with Subsection 501.03.

method of conveyance, approved by the Engineer, which minimizes the mixing of fresh concrete

and water. A tremie shall have a hopper at the top that empties into a watertight tube at least 10

inches in diameter.

The discharge end of the tube on the tremie shall include a device to seal out water while the tube

is first filled with concrete. An inflatable ball will not be permitted. The device shall keep its shape

and float without danger of deflation.

The placement shall be continuous to the elevations shown on the Plans and the resulting concrete

shall be monolithic and homogeneous.

Concrete shall not be deposited in water that has a temperature of 35°F or less. When the water

temperature is between 35°F and 40°F, the mixing water, the aggregates, or both shall be heated

as specified in Subsection 501.07(b).

A tremie shall be constructed of heavy-gauge steel pipe and consist of watertight joints between

the tremie sections with a diameter of not less than 10 inches. The tremie hopper shall have a

capacity of at least 1/2 cubic yard. When a batch is dumped into the hopper, the flow of the concrete

shall be induced by slightly raising the discharge tube, always keeping it in the concrete.

Tubes shall be kept continuously submerged in concrete during discharge. The depth that the tube

is submerged in concrete and the height of the concrete in the tube shall be sufficient to prevent

water from entering the tube. The Contractor shall continuously monitor the difference in elevation

between the top of the concrete and the end of the discharge tube.

Horizontal movement of discharge tubes through the concrete will not be allowed.

For minor quantities, at the sole discretion of the Engineer, a direct pumping method may be

approved. If a direct pumping method is to be implemented, the pipe discharging the concrete shall

consist of heavy-gauge steel sections. The Contractor shall demonstrate the ability to pump the

concrete without the pump line surging or otherwise moving in the water as concrete is being

pumped.

Cylinders cured as field cure shall be cured at the same temperature as the water covering the

concrete.

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501.11PUMPING. Where concrete is conveyed and placed by mechanically-applied pressure, the

equipment shall be suitable in kind and adequate in capacity for the work. The pump shall be capable of

pumping concrete within the specified slump limits. The use of aluminum pipe as a conveyance for the

concrete will not be permitted.

The operation of the pump shall be such that a continuous stream of concrete without air pockets is

produced. When pumping is completed, the concrete remaining in the pipeline, if it is to be used, shall be

ejected in such a manner that there will be no contamination of the concrete or separation of the

ingredients. The equipment shall be arranged so that no resulting vibrations may damage freshly placed

concrete.

501.12CONSTRUCTION JOINTS

variation or new location of joints shall require written permission of the Engineer. Feather edges

at construction joints will not be permitted. Joints shall be formed with inset formwork so that each

layer of concrete will have a thickness of not less than 6 inches.

has hardened, the surface of the set concrete shall be roughened in such a manner that will not

leave loosened particles or damaged concrete at the surface and shall be thoroughly cleaned of all

laitance, loose, and foreign material. Immediately prior to the placing of the new concrete, the

surface shall be saturated with water.

When shown on the Plans or ordered by the Engineer, the surface shall be thoroughly coated with

a very thin coating of mortar, neat cement grout, or epoxy bonding system and all forms drawn

tight against the face of the concrete. This coating shall not be allowed to dry out before being

covered with fresh concrete.

other pre-formed joint filler that may be shown in the Contract. Joint filler shall be cut to fit exactly

and shall completely fill the space that is shown on the Plans. Where a pour grade or caulking

grade filler is indicated to be used in the joints, that portion of the joint to be filled shall be formed

with a separate material (other than the pre-formed joint filler) that can easily be removed prior to

placement of the above indicated filler.

form continuous watertight joints.

Plans.

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501.13EXPANSION JOINTS. All expansion joints shall be constructed according to the details shown

on the Plans.

with a pre-formed self-expanding cork joint filler or other pre-formed joint filler that may be shown

in the Contract. Joint filler shall be cut to fit exactly and shall completely fill the space that is

shown on the Plans. Where a pour grade or caulking grade filler is indicated to be used in the joint,

that portion of the joint to be filled shall be formed with a separate material (other than the

expansion joint filler) that can easily be removed prior to placement of the above indicated filler.

the Plans or ordered by the Engineer.

501.14CONCRETE FINISHING

Other finish classes may be shown on the Plans for designated surfaces.

from those that are not to be exposed. On all surfaces, the cavities produced by form ties

and all other holes, honeycomb spots, broken corners or edges, and other minor defects

shall be thoroughly cleaned, saturated with water, and carefully pointed and trued with a

product that meets the requirements of Subsection 780.01. The manufacturer’s

recommendations shall be followed for surface preparation, mixing, application, and

curing.

All construction and expansion joints in the completed work shall be left carefully tooled

and free of all mortar and concrete. The joint shall be left exposed to its full length with

clean and true edges.

Areas that contain minor defects shall be repaired to the satisfaction of the Engineer. Minor

defects are defined as the intermittent presence of holes, honeycombing, chips, or spalls,

which are 6 inches or less in the longest dimension, and that do not penetrate deeper than

1 inch into the concrete. Surface voids or bugholes that are less than 1/4 inch in diameter

and less than 1/8 inch deep need not be repaired.

Major defects are anything beyond the scope of minor as described above. The Contractor

shall submit a corrective action proposal to the Engineer for all major defects.

501

shall be performed when an aesthetic finish is specified.

On all exposed surfaces, the cavities produced by form ties and all other holes, honeycomb

spots, broken corners or edges, and other minor defects shall be thoroughly cleaned,

saturated with water, and carefully pointed and trued with a mortar composed of the same

cement and fine aggregate and mixed in the same proportions used in the concrete being

finished, unless otherwise directed by the Engineer. Mortar used in pointing shall be not

more than 1 hour old. The mortar patches shall be cured for a minimum of 72 hours in

accordance with Subsection 501.15.

in the form and removing or striking off the excess with a template, forcing the coarse aggregate

below the mortar surface. Creation of concave surfaces shall be avoided. After the concrete has

been struck off, the surface shall be smoothed with a magnesium float.

Immediately after float finishing, the surface shall be given a broom finish, burlap drag finish, or

left smooth as determined by the Engineer.

surface shall be smoothed with a magnesium float.

the deck in accordance with the pre-placement meeting. The procedure shall provide for

adequate labor, equipment, and material supply to complete placement of concrete on the

entire deck, or specified portion thereof.

If, during the placement, unforeseen circumstances delay the progression of the pour to a

point where the concrete begins to lose plasticity, the Contractor shall be prepared to place

a bulkhead, as directed by the Engineer.

If at any time the screed machine does not advance in a 15-minute period due to delayed

concrete delivery, mechanical breakdown, or other problem, the Contractor shall

immediately cover concrete that is under the screed machine past the leading edge of the

concrete with wet burlap. Just before concrete placement is to begin, the burlap shall be

removed, the screed machine will be moved back, fresh concrete will be added to the area

that was directly under the screed to the leading edge, and the area will be vibrated again.

The screed machine may then be advanced forward to continue the placement.

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Approval of their methods and equipment does not relieve the Contractor of full

responsibility for obtaining the required surface finish.

Prior to texturing, the finished concrete surface shall be examined by the Contractor.

Surface irregularities greater than 1/8 inch in 10 feet in either the longitudinal or the

transverse direction shall be corrected in a manner acceptable to the Engineer. When a

bituminous concrete surface is to be placed on a bridge deck, the deviation shall not be

greater than 1/4 inch. When a sheet membrane is being applied, sharp ridges shall not be

allowed. Thin mortar or laitance, which may have accumulated ahead of the finishing

machine screed, shall be removed from the work site. These materials shall not be used to

fill depressions.

If the bridge deck concrete does not meet the above smoothness requirements, the

Contractor shall remove high spots up to 1/2-inch high by means of grinding. Any other

corrections shall be made only with the written approval of the Engineer. The use of bush

hammers will not be allowed. No concrete shall be removed that will result in a concrete

slab thickness less than that shown on the Plans.

Any deck that cannot be corrected by a method satisfactory to the Engineer shall be

removed and replaced at the Contractor’s expense.

Sidewalks shall receive their final finish with a fine bristled broom.

an artificial turf drag made of molded polyethylene or other material or method that will

provide an acceptable finish. The selection of turf drag or other method should be capable

of producing a surface texture with a horizontal peak-to-peak distance ranging from 0.02

inch to less than or equal to 0.25 inch and having a peak-to-peak amplitude of 0.005 inch

to 0.8 inch. A turf drag material or other acceptable method that will minimize tearing and

rolling of coarse aggregate from the surface shall be used.

The Contractor shall apply the finish texture in a transverse direction using hand methods.

Other directions may be allowed with the approval of the Engineer. All texturing shall be

performed from a work bridge immediately following the finishing operations and prior to

curing operations. A second work bridge will be required for curing purposes unless a

method using a single work bridge has been approved by the Engineer.

One pass of the turf drag over the finished area is desired. The drag shall leave a seamless

strip between passes. The finish texture resulting from the drag shall stop within 15 inches

of the curb face, rail anchor bolts, or edge of deck. Any buildup of concrete at the beginning

or end of the pass shall be hand troweled to provide an even transition.

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The drag shall produce a transverse, skid-resistant micro-texture acceptable to the

Engineer, but shall not tear the surface. If the drag is not producing an acceptable micro-

texture, the Contractor shall adjust the means and methods until an acceptable micro-

texture is achieved.

The Contractor shall check the drag material before the deck pour and from time-to-time

during finishing for tears, worn surface, or hardened concrete. The Contractor shall clean

or replace the drag as often as necessary to maintain a well-defined micro-texture.

The turf drag or other acceptable methods shall not be applied when the surface is so wet

or plastic that the ridges formed flow back into the valleys when the drag has passed, nor

shall dragging be delayed until the concrete is so hard that sharp ridges cannot be formed

by the drag. Fogging or similar methods shall be deployed to ensure that the surface does

not dry prematurely.

If the 10-minute maximum, as specified in Subsection 501.15(c), for applying the wet cure

cannot be met, then fogging of the area shall be performed in a manner that keeps the

relative humidity above the evaporation rate of the concrete surface, but not so excessive

that water begins to collect on the surface prior to texturing or other surface manipulating

procedures.

construction and accurately set so that the finished deck surface will conform to the profile

and transverse sections shown in the Plans. Finishing machine rail supports shall be placed

and adjusted to properly provide for the deflection of forms, falsework, and structural

supporting members which will occur during the placement of the concrete.

The finishing machine rail supports shall be spaced at a maximum of 2 feet on center and

of sufficient design as to secure the rail to prevent it from falling off the support. The screed

rails shall be configured to allow the screed machine and work bridges to be fully functional

over the entire deck area.

Sufficient screed rails shall be provided so that all rails necessary for any one continuous

pour may be preset and graded before the start of concreting operations. The removal of

screed rails and exposed chairs shall be accomplished without walking in the fresh concrete

and while the concrete is still plastic.

The Contractor shall furnish a work bridge or bridges of an approved type, capable of

spanning the entire width of the deck without deflection to the concrete slab surface.

501

and the operation shall be repeated as necessary to produce a uniformly consolidated,

dense, smooth surface. The final passage of the finishing machine shall result in a uniform

surface at the required grade and slope over its entire area.

Finishing machines shall be kept in true adjustment. Machines shall not be used until the

proper adjustments have been made and the adjustments have been checked and approved

by the Engineer.

Sufficient time shall be provided prior to beginning concreting operations for the finishing

machine to be operated over the full length of the bridge deck segment to be placed. This

test run shall be made with the screed adjusted to its finishing position. While operating

the finishing machine in this test, the screed rails shall be checked for deflection and proper

adjustment, the cover on slab reinforcement shall be measured, and the controlling

dimensions of slab reinforcement and forms shall be checked.

After the concrete is placed, it shall be struck off by one of the following methods:

suitable rails, and equipped with adjustable strike-off and finishing roller screeds

capable of producing the required finish surface for the full width of the bridge from

face-to-face of curbs.

pounds per linear foot and generating at least 6,500 vibrations per minute when

checked by a vibration reed-type tester, may be deployed. The vibrating screed shall

provide a uniform finish throughout its entire length and shall be properly adjusted

so as not to drive the aggregate more than 1/4 inch below the surface.

The concrete finishing machine, or screed, shall be oriented perpendicular to centerline of

the bridge. Screed supports shall extend beyond the end of the deck as needed to ensure

that the finishing machine can operate over the full length of the bridge deck segment to

be placed. The finishing machine or screed shall not be operated on a skew unless the

Contractor is able to demonstrate by calculation that the design deck thickness and cross

slopes can be maintained throughout the full length of the segment placed.

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In areas that are inaccessible to finishing machines, an approved manual vibratory-

equipped power screed with an approved grade-control method may be used with approval

from the Engineer. Smoothness shall be checked as specified in Subsection 501.14(d)(1)

to ensure a smooth ride and seamless transition to the finishing machine’s finished area. If

manual vibratory-equipped power screeds are used, then initial vibration of the concrete

for consolidation in those areas shall be of the minimal duration possible to avoid over-

vibration and loss of air entraining of the surface concrete in these areas.

Hand finishing will be allowed only in areas inaccessible to finishing machines or manually

driven vibratory-equipped power screeds. Hand screeds or bull floats shall be magnesium

and at least 10 inches in width. Care shall be taken not to overwork the concrete surface

during any finishing operation. Smoothness shall be checked as specified in Subsection

(d)(1) to ensure a smooth ride and seamless transition to the finishing machine’s

finished area.

CURING CONCRETE

Subsection 745.01. The effective cure time shall be only the time that the concrete has been

maintained in a wet condition with the concrete surface temperature above 50°F. If the concrete is

not maintained in a wet condition or the concrete surface temperature drops below 50°F, it shall

not be counted as effective cure time. The cure period will be extended 4 hours for every 1 hour

the concrete is below 50°F, beginning when the concrete temperature is raised to or exceeds the

minimum curing temperature.

Regardless of the curing medium specified, the entire surface of the newly placed concrete shall

be kept damp. This shall be achieved by applying water with a nozzle that atomizes the flow so

that a mist and not a spray is formed. The moisture shall not be applied under pressure directly

upon the concrete and shall not be allowed to accumulate in a quantity sufficient to cause a flow

or washing of the surface.

The atomized flow shall be applied continuously until the surfaces can be covered by the specified

curing mediums. For bridge barriers, curbs, and sidewalks the curing method shall be applied

within 15 minutes of the completion of the finishing process.

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Concrete components shall be cured for the times specified in Table 501.15A.

TABLE 501.15A – CURING TIMES FOR CONCRETE COMPONENTS

Type of

Construction Curing Methods Effective Cure

Time (Days)

Substructure Subsection 501.15(b)(1), (2),

(3), (5), (7), and (8)

Superstructure Subsection 501.15(b)(2) and (8) 7

Retaining walls Subsection 501.15(b)(1), (2),

(5), (6), and (8)

Headwalls Subsection 501.15(b)(1), (2),

(5), (6), and (8)

Sidewalks, curbs,

and gutters Subsection 501.15(b)(2) and (8) 7

There shall be no activity on the superstructure during the cure period.

following specified methods:

all exposed surfaces with water for the entire required curing period.

of approved burlap that has been pre-soaked with water. The burlap shall then be covered

with a lapped layer of white polyethylene sheeting. Once the concrete superstructure has

hardened sufficiently, a stream of water, applied with a soaker hose or similar device, shall

be run continuously under the polyethylene sheeting until the cure period is complete.

inches of approved sand that shall be kept wet for the entire curing period.

with a blanket of white polyethylene sheeting, maintained and fastened to provide a nearly

airtight condition in contact with the surface where possible. If, in the opinion of the

Engineer, this cover is not adequately provided or maintained to ensure the proper

conditions for the concrete cure, then the white polyethylene sheeting cure shall be

terminated and another method substituted.

501

covered with a blanket of white burlap-polyethylene sheeting. The burlap shall be

thoroughly dampened prior to placing and shall be placed next to the concrete. All joints

shall be lapped a minimum of 18 inches. The burlap shall be kept damp throughout the

curing period.

forming curing compounds may be used for curing concrete in minor drainage structures.

All other uses of curing compounds shall be approved in writing by the Engineer. Only

membrane-forming curing compounds approved by the Agency’s Materials Testing and

Certification Section shall be used.

When membrane curing is used, the exposed concrete shall be thoroughly sealed

immediately after the free water has left the surface. The concrete inside the forms shall be

sealed immediately after the forms are removed and necessary finishing has been done.

The solution shall be applied in one or two separate applications. If the solution is applied

in two increments, the second application shall follow the first application within 30

minutes. Satisfactory equipment shall be provided, together with means to properly control

and ensure the direct application of the curing solution to the concrete surface to result in

a uniform coverage of the surface area at the rate of 1 gallon of solution for every 150

square feet.

If rain falls on the newly coated concrete before the film has dried sufficiently to resist

damage, or if the film is damaged in any other manner, a new coat of the solution shall be

applied to the affected portions equal in curing value to that specified above.

Should the surface be subject to continuous injury or the use of curing compound results

in a streaked or blotchy appearance, the method shall be stopped and water curing applied.

approved by the Engineer and shall conform to the requirements of Subsection

(b)(4). The airtight condition shall be obtained by the addition of a uniform sand

cover with a minimum depth of 2 inches.

with a blanket of cotton mats that has been pre-dampened with water. The mats shall be

maintained in a damp condition until the curing period is complete.

If, in the opinion of the Engineer, the Contractor’s curing procedure is not producing an adequate

cure, the Engineer may direct a change in the cure method at no additional cost to the Agency.

501

within a maximum lag time of 10 minutes and without interruption. If this lag time cannot be met,

then fogging of the area shall be performed in a manner that keeps the relative humidity above the

evaporation rate of the concrete surface, but not so excessive that water begins to collect on the

surface prior to texturing or other surface manipulating procedures.

501.16LOADING OF CONCRETE. After the concrete has been placed and the finishing operations

concluded, it shall not be walked on or disturbed in any manner, including removal of forms, for a

minimum period of 18 hours. If retarder is used as an admixture, this minimum period may be extended

as directed by the Engineer.

concrete cure is maintained in accordance with Table 501.15A, and until the field cured test

cylinders have attained 85% of the compressive strength specified in Table 501.03A. However,

the Contractor may erect forms for subsequent concrete placement on footings after 18 hours have

elapsed from the time that the footing placement was completed, provided the concrete has

sufficient strength to allow it to be worked on without damage, and proper cure is maintained.

Static loads, such as forms, reinforcing steel, or other materials necessary for construction, may be

placed on any concrete after it has been in place 72 hours, or a compressive strength of 1,800 psi

has been obtained, provided proper curing is maintained. Superimposed loads from subsequent

concrete pours will not be allowed on any substructure unit or section in place until the field cured

test cylinders have attained 85% of the compressive strength specified in Table 501.03A and

provided curing of the supporting section is maintained in accordance with Table 501.15A.

materials necessary for deck construction, shall not be placed on deck concrete until the effective

cure time specified in Table 501.15A is complete and the field-cured test cylinders for this concrete

have attained 85% of the compressive strength specified in Table 501.03A.

The Contractor shall keep bridge floors free of all motor vehicles, transit mixers, and heavy

construction equipment until the curing period is satisfactorily completed, the field-cured test

cylinders for the bridge floor concrete have attained the compressive strength specified in Table

A, and the field-cured test cylinders for the curb concrete or bridge rail concrete, as

applicable, have attained 85% of the compressive strength specified in Table 501.03A.

previously placed concrete has been in place a minimum of 72 hours.

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501.17METHOD OF MEASUREMENT. The quantity of Performance-Based Concrete, Class PCD;

Performance-Based Concrete, Class PCS; and Performance-Based Concrete, Class SCC to be measured

for payment will be the number of cubic yards of the class of concrete specified in the complete and

accepted work, as determined by the prismoidal method using dimensions shown on the Plans or as

directed by the Engineer.

The quantity of concrete shall exclude the volume of steel or other stay-in-place forms and form filling

materials. No deductions will be made for the volume of concrete displaced by steel reinforcement,

structural steel, expansion joint material, scuppers, weep holes, conduits, tops of piles, scoring, chamfers

or corners, inset panels of 1-1/2 inches or less in depth, or any pipe less than 8 inches in diameter.

If a trial pour is performed at the request of the Engineer, the quantity of concrete to be measured for

payment will be the number of cubic yards of the class of concrete specified for the trial pour, as

determined by the prismoidal method using dimensions specified in the Contract or as directed by the

Engineer.

501.18BASIS OF PAYMENT. The accepted quantity of Performance-Based Concrete, Class PCD;

Performance-Based Concrete, Class PCS; and Performance-Based Concrete, Class SCC will be paid for

at the Contract unit price per cubic yard. Payment will be full compensation for performing the work

specified, including designing the mix, performance of trial pours, and satisfactory finishing and curing.

Payment will also be full compensation for furnishing all forms, materials, including joint filler and bond

breaker, labor, tools, admixtures, and equipment, including automatic temperature recording units, trial

batches, and incidentals necessary to complete the work.

The cost of heating materials and protecting the concrete against cold weather, and any additional cost for

cement, will not be paid for separately but will be considered incidental to the Contract unit prices for the

applicable concrete pay items.

The cost of furnishing testing facilities and supplies at the batch plant and the setting of inserts,

benchmarks, and bridge plaques furnished by the Agency will not be paid for separately but will be

considered incidental to the Contract unit prices for the applicable concrete item.

Costs for all materials, labor, and incidentals for steel or other stay-in-place forms and form filling

materials will not be paid for separately but will be considered incidental to the Contract unit prices for

the applicable concrete item.

Payment will be made under:

Pay Item Pay Unit

501.3700 Performance-Based Concrete, Class PCD ................................................Cubic Yard

501.3800 Performance-Based Concrete, Class PCS .................................................Cubic Yard

501.3900 Performance-Based Concrete, Class SCC ................................................Cubic Yard

502

5-51SECTION 502 – SHORING SUPERSTRUCTURES

502.0 1 DESCRIPTION . This work shall consist of furnishing the necessary shoring, or vertically jacking of any structure or bearing to a position immediately above its present location, holding it in position during any construction process, lowering it to its supports, removing all shoring or falsework, and cleaning up the site. 502.0 2 CONSTRUCTIO N DRAWINGS . Construction drawings shall be submitted in accordance with the requirements of Subsection 105.06 . The Contractor shall submit the drawings and associated calculations, procedures, and details a minimum of 28 days prior to the anticipated start of work. 502.0 3 CONSTRUCTIO N REQUIREMENTS . Associated details, procedures, and calculations for shoring and jacking shall conform to the requirements of the AASHTO LRFD Bridge Design Specifications and AASHTO LRFD Bridge Construction Specifications . The Contractor shall be responsible for the strength, capacity, and performance of the construction methods employed. When components or materials that are not otherwise specified for removal are removed from the structure during shoring operations and the components or materials are to be re -installed in the construction, the components or materials shall be ca refully removed and salvaged by the Contractor. Components or materials to be retained and re -installed shall be stored at the location specified in the Contract or as directed by the Engineer. The Contractor shall take every precaution necessary to prevent damage to remaining components or materials and those to be retained for re -installation. Damage to remaining structure components or materials and to those to be re -installed shall be repaired or replaced by the Contractor both to the satisfaction of the Engineer and at no additional cos t to the Agency. 502.0 4 METHO D OF MEASUREMENT . The quantity of Shoring Superstructure to be measured for payment will be on a lump sum basis for each location in the complete and accepted work specified in the Contract or o rdered by the Engineer. Unless otherwise specified in the Contract, all work for removing, salvaging, stockpiling, and re -installing existing structure components or materials during the Contractor’s shoring operations will not be measured for payment but will be considered incidental to Shoring Superstructure.