2461Structural Concrete

2461.1DESCRIPTION

This Work consists of producing, providing, placing, curing, and protecting cast -in-place Portland cement concrete for placement in Structures, pavements, and Incidental construction. A Definitions For the purpose of the Work specified in section 2461, “Structural Concrete,” the Department defines: Absorption Factor Factor used to determine the water contained within the pores of the Aggregate and is held within the particles by capillary force. Batch water Water actually batched into the truck by the batcher. Batch water includes potable water and clarified water. Free moisture The water that is carried on the surface of the Aggregate that becomes part of the Total water. Mix design water The maximum allowable water content for 1 cubic yard of concrete. Ready-mix Concrete Either central-mixed concrete proportioned and mixed in a stationary plant and hauled to the point of placement in revolving drum agitator trucks or a truck mixer or truck-mixed concrete proportioned in a stationary plant and fully mixed in truck mixers. Ready-mix Producer or “Producer” Party that is producing the concrete for the Contract. It is understood that the Ready- mix Producer is the agent of the Contractor.

Real Time The actual time during which something takes place. Temper water Water added in mixer to adjust slump Total actual water The water in the concrete mixture at the time of placement from any source other than the amount absorbed by the Aggregate. It includes all Batch water placed in the mixer, free moisture on the Aggregate, and any water added to the ready-mix truck prior to placement. Total moisture factor Factor used to determine total amount of water carried by a given wet Aggregate. Total water Batch water added to free moisture. Total water may also include the water used in diluting admixture solutions. Water/Cement (W/C) Ratio W/C Ratio is defined as the ratio of the Total water weight to the total cementitious weight, which includes cement and supplementary cementitious Materials.

2461.2MATERIALS

A Cementitious Materials Provide cementitious Materials from certified sources listed on the APL. Use Type I, I/II, IS, IL, or IP cement to produce Type 1 non-air-entrained concrete. Use Type I, I/II, IS, IL, or IP cement and an air-entraining admixture listed on the APL to produce Type 3 air-entrained concrete. Use Type III Portland cement as allowed by the Contract or the Engineer. A.5 Ternary Mixes Ternary mixes are defined as Portland cement or Type IL and two other supplementary cementitious Materials, Type IT blended cement, or blended cement (excluding Type IT) and one other supplementary cementitious Material. B Aggregates Provide Aggregates from sources listed on the MnDOT Concrete Aggregate Properties list.

Provide water from potable sources. The Concrete Engineer will allow clarified water as a substitution for potable water in accordance with the following:

Provide admixtures from the APL for concrete grades shown in Table 2461.2-6 and Table 2461.2-7. D.1 Allowable Admixtures Use of any of the following admixtures are at the Contractor’s discretion:

D.2 Use of Accelerating Admixtures Use of Type C, Accelerating Admixture, and Type E, Water Reducing and Accelerating Admixtures, require approval of the Concrete Engineer, in conjunction with the Engineer, unless otherwise allowed in the Contract. The Engineer will permit the use of Type C or Type E accelerating admixtures only when all of the following conditions exist:

E Concrete Mix Designs E.1 Classification of Concrete The Department will classify concrete by mix number to identify type, grade, consistency, and Aggregate size, if any, in accordance with Table 2461.2-1. Table 2461.2-1 Mix Number Identification First Digit Second Digit Third Digit Fourth Digit Additional Digits Type Designation Grade Designation Maximum Slump Coarse Aggregate Gradation Designation Additional Digits Allowed or as Specified

E.1.a Type Designation Provide Type 1 or Type 3 concrete in accordance with Table 2461.2-2: Table 2461.2-2 Concrete Type Designation Concrete Type Target Air Content * 1 2.0 percent 3 6.5 percent ǁ * For concrete mix design purposes only. ǁ Unless otherwise required by 2301, “Concrete Pavement,” or elsewhere in the Contract. E.1.b Grade Designation The Department will designate concrete grade in accordance with Table 2461.2-6 and Table 2461.2-7 using a letter designating the following:

for Concrete” E.1.c Slump Designation The Department will designate the slump range as defined by the grade designation in accordance with Table 2461.2-6 and Table 2461.2-7. E.1.d Coarse Aggregate Gradation Designation Select the appropriate coarse Aggregate gradation designation in accordance with Table 2461.2-3 based on the intended use and the gradation requirements in 3137, “Coarse Aggregate for Concrete.” Table 2461.2-3 Coarse Aggregate Gradation Designation Designation Coarse Aggregate Gradation 1 2301, “Concrete Pavement” only 2 #67* 3 #7* 4 #89* 7 CA-70 8 CA-80 * Gradation sizes designated per ASTM C33/C33M, Standard Specification for Concrete Aggregates, Table 3. E.1.e Additional Concrete Mix Designation Digits Specialty concrete mixes require additional concrete digits in accordance with Table 2461.2-6. Use “EX” for exposed Aggregate mixes, “CO” for colored concrete mixes, and “FRC” for fiber reinforced concrete mixes. The Contractor may add additional digits to the right of the required digits in the concrete mix number.

E.2 Concrete Mix Design Requirements Acceptance of concrete is contingent on meeting all specification requirements, including but not limited to requirements related to field placement and performance . E.2.a Department Designed Concrete Mixes The Department will provide mix designs for the concrete defined in Table 2461.2-4 and Table 2461.2-5. E.2.a(1) Department Designed Concrete Requirements No additional submittal is required for Table 2461.2-4 mix designs. Table 2461.2-4 Department Designed Concrete Mixes Type of Concrete Mix Number Specification Mix Design Location Field Batched Patching Mix 3U18 2302, “Concrete Pavement Rehabilitation” Table 2302.2-1 Low Slump Concrete 3U17A 2404, “Concrete Wearing Course for Bridges” Table 2404.2-1 Bagged Patching Mix 3U18 and 3U58M 3105, “Bagged Portland Cement Concrete Patching Mix 3U18 and 3U58M” Table 3105.2-2 E.2.a(2) Grout and Lean Mix Backfill Submit final mix design proportions on the General Concrete Mix Design Submittal for Grout and Lean Mix Backfill in accordance with Table 2461.2-5. Table 2461.2-5 Concrete Mix Design Requirements for Grout and Lean Mix Backfill Mixes Mix Number Maximum W/C Ratio Water Content (pounds) Cement Content (pounds) Fly Ash Content (pounds) Fine Aggregate Calculation (pounds) Coarse Aggregate Calculation (pounds) Percent Air Content Slump Range Minimum 28-Calendar Day Compressive Strength, f’c 1A Grout* 0.50 379 758 0 100 percent † 0 3.0 As needed 4000 psi 3A Grout * 0.44 379 865 0 100 percent † 0 10.0 As needed 4000 psi Lean Mixǁ 1.00 375 125 250 50 percent† 50 percent† ǂ N/A 10 inches ± 1 inch # * Do not provide 1A or 3A grout containing coarse Aggregate or fly ash. ǁ Coarse Aggregate quality meets requirements of 3137.2D.1, “Coarse Aggregate for General Use.” † After adding the specified quantities of cement, fly ash, and water, provide the remaining A ggregate to an absolute volume

27.0027.27 cubic feet

ǂ Meeting #67 gradation as shown in Table 3137.2-4. # Maximum 28-Calendar Day compressive strength of 1500 psi.

E.2.b Contractor Designed Concrete Mixes The Contractor will provide concrete mix designs for concrete defined in Table 2461.2-6 and Table 2461.2-7 and elsewhere as specified in the Contract. The Contractor assumes full responsibility for the concrete mix design and performance of the concrete, including meeting all specification requirements . E.2.b(1) General Concrete Mix Design Requirements The Department specifies the concrete mix design requirements for Contractor designed mixes in accordance with Table 2461.2-6.

Table 2461.2-6 Concrete Mix Design Requirements (Not applicable to High Performance Concrete or Mass Concrete) Concrete Grade Mix Number Intended Use *

Maximum W/C Ratio ║ Maximum Cementitious Content (pounds/ cubic yard) Maximum percent SCM (Fly Ash/ Slag/Ternary) Design Slump Range (inches) Minimum 28- day Compressive Strength, f’c 3137, “Coarse Aggregate for Concrete.” B Bridge Substructure 3B52 Abutment, stems, wingwalls, paving brackets, pier columns, pier caps, pier struts 0.45 750 30/35/40 2 - 5 4000 psi 2D.1 F Flatwork 3F32 Curb and gutter 0.42 750 30/35/0 1/2 - 3 # 4500 psi 2D.1 3F52 3F57EX † 3F52CO ‡ Sidewalk, curb and gutter, slope paving, median Sidewalk, driveway entrances, ADA pedestrian Sidewalk 0.45 750 25/30/0 2 – 5 4500 psi 2D.1 G General Concrete 1G52 Footings and pilecap 0.55 750 30/35/40 2 - 5 4500 psi 2D.1 3G52 Footings, pilecap, walls, cast-in- place manholes and catch basins, fence posts, signal bases, Light Pole foundations, erosion control Structures, cast-in-place box culverts, Culvert headwalls, open flumes, cast-in-place wall stems 0.45 750 30/35/40 2 - 5 4500 psi 2D.1 M Median Barrier 3M12 Slipform barrier, Median barrier, non-bridge 0.42 750 30/35/40 1/2 - 1 # 4500 psi 2D.1 3M52 Barrier, Median barrier, non- bridge 0.45 750 30/35/40 2 – 5 4500 psi 2D.1 P Piling 1P42 MSE and gravity wall leveling pad 0.63 750 30/35/40 2 – 4 3000 psi 2D.1 1P62 Piling, spread footing leveling pad 0.63 750 30/35/40 3 – 6 3000 psi 2D.1 R Pavement Rehabilitation 3R52 CPR – Full-depth concrete repairs, concrete base 0.45 750 30/35/40 2 – 5 4000 psi 2D.3

Concrete Grade Mix Number Intended Use *

Maximum W/C Ratio ║ Maximum Cementitious Content (pounds/ cubic yard) Maximum percent SCM (Fly Ash/ Slag/Ternary) Design Slump Range (inches) Minimum 28- day Compressive Strength, f’c 3137, “Coarse Aggregate for Concrete.” S Bridge Superstructure 3S12 Slipform Bridge barrier, parapets, end post 0.42 750 30/35/40 1/2 - 1 # 4000 psi 2D.2 3S52 Median barrier, raised median, pilaster, curb, Sidewalk, approach panel, formed Bridge barrier, parapet, end post, collar 0.45 750 30/35/40 2 - 5 4000 psi 2D.2 X Miscellaneous Bridge 1X62 Cofferdam seals, rock sockets, drilled shafts 0.45 750 30/35/40 3 – 6 5000 psi 2D.1 3X62 Drilled shafts above the frost line 0.45 750 30/35/40 3 – 6 5000 psi 2D.1 Y Bridge Deck 3Y42-M § 3Y42-S § Bridge decks, integral abutment diaphragms, pier continuity diaphragms, expansion joint replacement mix 0.45 750 30/35/40 2 - 4 4000 psi 2D.2 3Y47 ** Deck patching mix 0.45 750 30/35/40 2 – 4 4000 psi 2D.2 If the intended use is not included elsewhere in the Specification or Special Provisions, use mix 3G52, unless otherwise dire cted by the Engineer. ║ The minimum Water/Cement (W/C) ratio is 0.30. † Mix 3F57EX requires the use of Coarse Aggregate Designation “7,” “2” or “3” for the 4th digit in accordance with Table 2461.2-3. ‡ Identify the specific color used on the Certificate of Compliance. Colored concrete is only allowed when specified in the Plans or the Contract. # Adjust slump in accordance with 2461.3G.7.a, “Concrete Placed by the Slip-Form Method,” for slip-form concrete placement. § The “-S” indicates a Bridge deck with a structural slab and “-M” indicates a monolithic Bridge deck. ** Mix 3Y47 requires the use of Coarse Aggregate Designation “7” or “3” for the 4th digit in accordance with Table 2461.2-3.

E.2.b(2) High-Early Concrete Mix Design Requirements Design High-early (HE) concrete to achieve the minimum design strength and time required in accordance with Table 2461.2-7. Unless otherwise included in the Plans, HE concrete requires approval of the Engineer before incorporation into the Work. The Engineer will allow one of the following methods to determine minimum time to opening:

“Field Control Strength Cylinders.”

“Estimating Concrete Strength by the Maturity Method.” The Department defines the concrete mix design requirements for High-early concrete in accordance with Table 2461.2-7. Table 2461.2-7 High-Early (HE) Concrete Requirements (Not applicable to Bridge Superstructure or Mass Concrete) Mix Number Concrete Grades Allowed Minimum Design Time Maxim um W/C Ratio Maximum Cementitious Content (pounds/ cubic yard)* Slump Range Minimum Design Strength Minimum 28-Calendar Day Compressive Strength, f’c

“Coarse Aggregate for Concrete” 1PHE62 ǁ P - 0.63 750 3 – 6 inches - 3000 psi 2.D.1 3HE32 F 48 hours 0.42 750 1/2 – 3 inches † 2000 psi 4500 psi 2.D.1 3HE52 F 48 hours 0.42 750 2 – 5 inches 2000 psi 4500 psi 2.D.1 3HE52 B and G 48 hours 0.42 750 2 – 5 inches 3000 psi 4500 psi 2.D.1 3YHE52 Y (Repairs Only) 48 hours 0.42 750 2 – 5 inches 3000 psi 4000 psi 2.D.2 3RHE52 R (Repairs Only) 48 hours 0.42 750 2 – 5 inches 2000 psi 4000 psi 2.D.3 * Supplementary cementitious Materials allowed. ǁ Used only for placing concrete in piles during freezing temperatures, provide 30 percent additional cement to the concrete mix for concrete 10 feet below the ground line or water line in accordance with 2451.3D.6, “Cast-in-Place Concrete Piles.” † Adjust slump in accordance with 2461.3G.7.a, “Concrete Placed by the Slip-Form Method.”

E.2.b(3) Project Specific Mix Design Requirements Submit Project specific Contractor designed mixes on the Project Specific Structural Concrete Mix Design Submittal forms in accordance with Table 2461.2-8 and the Contract.

Table 2461.2-8 Project Specific Contractor Designed Mixes Concrete Grade Intended Use Specification 3137 “Coarse Aggregate for Concrete” A Concrete Pavement 2301, “Concrete Pavement” 2.D.3 M, V, W, Z Precast Concrete 2462, “Precast Concrete” Varies HPC High Performance Concrete 2401, “Concrete Bridge Construction” 2.D.2 MC Mass Concrete Special Provision 2401 Varies SCC Self-consolidating Concrete Special Provision 2401 Varies CLSM, LCCF Cellular Concrete Grout 2519, “Cellular Concrete” None Non-MnDOT Designated Per Contract Per Contract Per Contract All concrete grades Delivery Time is > 90 minutes 2461.3G.3.a, “Delivery Time Beyond 90 minutes” Varies

E.3 Submittal Requirements At least 21 Calendar Days before initial placement of the concrete, submit the appropriate General concrete mix design form to the Concrete Engineer for review. Use the most current forms, specific gravity, and absorption data available from the MnDOT Concrete Engineering website. Design the concrete mix to an absolute volume of 27.00 – 27.27 cubic feet. MnDOT will review the Contractor’s proposed mixture design solely for compliance with applicable mix design properties in 2461.2, “Structural Concrete, Materials.” The Department makes no guaranty or warranty, either express or implied, that compliance with mix design properties ensures compliance with any other requirements. Table 2461.2-9 specifies the mix design submittal requirements for Level 1 and Level 2 mixes.

Table 2461.2-9 Mix Design Submittal Requirements

SCM Substitution Limits Fine Aggregate Limit Gradation Requirements Preliminary Test Data Requirements Submittal Package Level 1 mixes * Fly Ash: 0 – 15 percent Slag: 0 – 35 percent 40 – 45 percent of total Aggregate by volume ǁ 3126, “Fine Aggregate for Portland Cement Concrete” and 3137, “Coarse Aggregate for Concrete” None General Concrete Mix Design Level 2 mixes Fly Ash: > 15 percent Ternary: Any None Use Either: 3126, “Fine Aggregate for Portland Cement Concrete” and 3137, “Coarse Aggregate for Concrete” or Job Mix Formula (JMF) 2461.2E.3.a, “Preliminary Test Data Requirements for Level 2 Mixes” Use Either: General Concrete Mix Design or General Concrete Mix Design (JMF) * High-early concrete in accordance with Table 2461.2-7 is defined as a Level 1 mix. ǁ Fine Aggregate limit does not apply to exposed Aggregate concrete mixes. E.3.a Preliminary Test Data Requirements for Level 2 Mixes For Level 2 mixes, submit the proposed mix design proportions on the General concrete mix design submittal based upon either a suitable experience record or conventional trial mixtures not to exceed the limits specified in Table 2461.2-6 or Table 2461.2-7. E.3.a(1) Suitable Experience Record A suitable experience record consists of at least 30 consecutive tests, or 2 groups of consecutive tests totaling at least 30 tests, within the previous 18 months. If the Contractor does not have 30 tests, the Concrete Engineer will consider a minimum of 10 test results representing a time period of at least 45 Calendar Days. The Concrete Engineer considers a suitable experience record to have the following characteristics as compared to the proposed mix:

above the required 28-Calendar Day compressive strength

proposed

those expected for the proposed Work Submit test results on the Strength test data sheet as part of the General concrete mix design submittal. The Concrete Engineer reserves the right to request batching data representing the suitable experience record submittal. E.3.a(2) Conventional Trial Mixtures If the Contractor does not have a suitable experience record as required in 2461.2E.3.a(1), “Suitable Experience Record,” establish concrete proportions from trial mixtures, utilizing an AASHTO accredited laboratory in accordance with the following:

Work at the W/C Ratios or cementitious Materials content that will produce a strength meeting or exceeding the required 28-Calendar Day compressive strength (f’c) in accordance with Table 2461.2-6 or Table 2461.2-7

slump range

produce air content within ± 0.5 percent of target air content

make and cure at least 3 test cylinders for 28-Calendar Day breaks in accordance with ASTM C192, Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory. For HE concrete mixes, in addition to the 28-Calendar Day cylinders, make a set of 3 test cylinders for 48-hour breaks in accordance with ASTM C192, Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory Submit all test results for the trial mixtures, certified by the AASHTO accredited laboratory, in addition to the General concrete mix design submittal. E.3.b Determining the Required Average Strength Based upon the following information select the mix design proportions required to produce f’cr. Using the Test Data spreadsheet, determine the following:

2461.2-10

Table 2461.2-10 Required Average Strength (f’cr) Equations* Required Average Strength f’c ≤ 5000 psi* f’cr = f’c + 1.34S or f’cr = f’c + 2.33S – 500 f’c > 5000 psi f’cr = 0.90f’c + 2.33S *When f’c ≤ 5000 psi, f’cr is the larger value computed from the equations. E.4 Contractor Mix Design Adjustments The Department will allow mix design adjustments based upon the criteria as defined in Table 2461.2-11: Table 2461.2-11 Mix Design Adjustments Adjustments/Requirements Type of Change or Adjustment Mix Design Resubmittal Requirements Level 1 mixes Cementitious Sources Admixture Sources Admixture Dosage Rate No resubmittal required Aggregate Sources Aggregate Proportions Any cementitious proportion (≤ 15 percent max fly ash) Resubmittal of Mix Design Any cementitious proportion (> 15 percent max fly ash) Resubmittal in accordance with 2461.2E.3.a, “Preliminary Test Data Requirements for Level 2 Mixes” Level 2 mixes Cementitious Sources Admixture Dosage Rate No resubmittal required Aggregate Source, no change in Aggregate Class ≤ 5 percent Total Cementitious ≤ 10 percent Individual Aggregate Weights Resubmittal of Mix Design Aggregate Source and Class of Coarse Aggregate Supplementary Cementitious Proportion > 5 percent Total Cementitious > 10 percent Individual Aggregate Weights Admixture Sources Resubmittal in accordance with 2461.2E.3.a, “Preliminary Test Data Requirements for Level 2 Mixes” * Only one (1) increase in total cementitious allowed per mix design, next adjustment requires resubmittal in accordance with 2461.2E.3.a, “Preliminary Test Data Requirements for Level 2 Mixes”

E.5 MnDOT Review for Continual Acceptance of Contractor Mix Designs The Concrete Engineer will review test results relating to each individual Contractor concrete mix design. The Concrete Engineer will review the following test results:

Provided the concrete continues to meet specification requirements, the Contractor will have that mix design available for future use.

F Concrete Yield The Department defines concrete yield as the ratio of the volume of mixed concrete, less accountable waste, to the planned volume of the Work constructed. The Department will not assume responsibility for the yield from a given volume of mixed concrete.

2461.3CONSTRUCTION REQUIREMENTS

A Batching Equipment A.1 Mixer Requirements Provide stationary mixers or truck mixers. A.2 General Condition Maintain mixers as necessary to detect changes in condition due to accumulations of hardened concrete or mortar and examine to detect wear of blades. Replace or recondition pickup and throwover blades in mixers with a rated capacity less than 14 cubic feet showing a blade wear loss of greater than 1/2 inch, and pickup and throwover blades in mixers of greater capacity, showing a blade wear loss of no greater than 3/4 inch from the original factory dimensions. A.3 Manufacturer's Rating Plate Provide mixers that include the manufacturer’s rating plate, showing the following information:

A.4 Drum Speed for Stationary Mixers Operate the drum speed in the mixer as specified by the manufacturer or as directed by the Engineer. A.5 Auxiliary Equipment Requirements Provide mixers equipped with the following:

each batching cycle

in increments no greater than 1/4 gallon in full view A.6 Mixer Capacity Do not exceed the manufacturer’s rated capacity of the mixer when mixing a single batch of concrete. Batch concrete in volumes the mixer can accommodate without spilling, leaking, or segregating during the charging, mixing, or discharging operations. A.7 Mixing Time For the purpose of the Work specified in 2461.2E, “Concrete Mix Designs,” the Department defines the mixing time as the time period beginning when the cement and Aggregates enter the mixer drum and ending when the discharge begins.

Refer to the manufacturer’s recommended minimum mixing time for single drum and dual drum mixers. In the absence of manufacturer’s recommendation, the Engineer will designate the minimum mixing time. The minimum mixing time for any concrete batch is 60 s. The Contractor may reduce the manufacturer’s recommended minimum mixing time or the Engineer designated mixing time if the Contractor obtains uniform mixing in accordance with 2461.3E, “Mixing Requirements,” and as approved by the Engineer, in conjunction with the Concrete Engineer. If there is evidence of inadequately mixed concrete (unmixed or partially mixed Materials) during concrete placement, the Engineer may direct an increase in the mixing time. A.8 Turbine Type Mixers Provide turbine type mixers meeting the applicable requirements for conventional type mixers in accordance with 2461.3A.1, “Mixer Requirements,” through 2461.3A.7, “Mixing Time,” and this subsection. Maintain the mixer drum in a cylindrical shape within 3/4 inches from the original factory dimensions at any point. Maintain the mixer discharge gate in a mortar tight condition in the closed position. Replace or recondition mixer paddles showing a wear loss greater than 1/2 inch from the original factory dimensions. Add the mixing water to the batch Materials in a manner that distributes the water to the inner or central areas of the drum. Start the flow of water before introducing the solid batch Materials into the mixer drum. During mixing, operate the paddles at a speed between 20 revolutions and 30 revolutions per minute. After adding the batch Materials to the drum, mix the concrete for an additional 60 seconds. A.9 Horizontal Axial-Revolving Blade Type Mixers Provide horizontal axial-revolving blade type mixers (single or multiple shaft) in accordance with the applicable requirements for conventional type mixers in accordance with 2461.3A.1, “Mixer Requirements,” through 2461.3A.7, “Mixing Time,” and this subsection. Charge the water, Aggregates, and cement in the sequence recommended by the manufacturer. Test the concrete uniformity as directed by the Engineer. The Engineer will use concrete uniformity tests to determine the minimum mixing time. B Transportation Units B.1 General Requirements Equip transportation units intended for both mixing and agitating with watertight revolving drums mounted, powered, and fitted with properly designed mixing blades in accordance with 2461.3A.1, “Mixer Requirements,” through 2461.3A.7, “Mixing Time.” Provide units capable of combining the ingredients into a homogeneous mixture and designed to provide two drum speeds, one for mixing and the other for agitating. Provide units capable of delivering the concrete without segregation or loss of any of the batch Materials . Equip the mixer drum with a working counting device to record the number of revolutions. Equip dump trucks and agitator trucks with vibrators to aid in discharge, are mortar tight, capable of complete discharge of the concrete, and in accordance with 2301.3F, “Placing Concrete.”

B.2 Capacity of Transportation Units Refer to the truck mixer manufacturer’s certification plate attached to the unit for the maximum capacity of the unit. If the unit will not satisfactorily mix the maximum volume shown, reduce the batch volume to allow proper mixing or discontinue use of the mixing unit as directed by the Engineer until the problem is corrected. C Handling and Storing Materials C.1 Batch Material Requirements Do not change the source, kind, or gradation of batch Materials after the start of concrete production for the Work unless otherwise approved by the Engineer. If the Engineer approves use of different Material, completely exhaust the supply on hand before changing to the different Material. If delivering freshly washed Aggregates to the batching plant, drain the Aggregates for at least 12 hours before using in the batching operation. If draining freshly washed Aggregates at the site of the batching plant, completely separate the drained Material from the undrained Materials, and provide for the disposal of water that accumulates from the drainage of M aterials. Provide smooth, firm, and well-drained stockpile sites cleared of vegetation and extraneous matter. Where the natural foundation is unsatisfactory, as determined by the Engineer, construct the stockpiles on suitable platforms. Construct suitable bulkheads or partitions to separate different kinds of Aggregate, gradation, or water content. Construct stockpiles by methods that hold segregation and degradation to a minimum . If the Engineer sees segregation or degradation, the Engineer may designate that pile as unacceptable for use. Do not use Aggregates used to construct runways for loading or hauling E quipment in concrete batches. Use of Aggregates from the bottom 1 foot of a stockpile placed on an unprepared surface in concrete batches is allowed only under the Engineer’s direct supervision and if the Material meets requirements of 3126, “Fine Aggregate for Portland Cement Concrete,” 3131, ”Intermediate Aggregate for Concrete, “ and 3137, “Coarse Aggregate for Concrete.” Provide Aggregates in accordance with the specified gradation requirements. The Engineer will consider Aggregates unacceptable if the variation in moisture content carried by any of the Aggregates causes a marked variation in the consistency of successive batches of the mixed concrete, and will suspend operations until corrected. C.2 Concrete Temperature Control Produce concrete at temperatures from 50°F to 90°F and maintain temperatures until deposited in the Work. If necessary to maintain placement temperature, uniformly heat or cool the water, Aggregates, or both, before introduction into the mixer. Control the temperature of the mixing water during heating or cooling. Use Aggregate at temperatures from 32°F to 130°F. Do not allow cementitious Material to contact other batch Material when the Aggregate temperature exceeds 130°F. Do not heat the cement, add salt, or add chemical admixtures to the concrete mix to prevent freezing.

Use a heating system to heat batch Materials as approved by the Engineer. Do not use steam jets to spot heat the Material as the Work progresses. Do not place mixer heaters intended for heating the batch Materials in the mixer drum. D Batching Requirements The Concrete Engineer will allow only large capacity Scale companies authorized by the Minnesota Department of Commerce, Weights and Measures Division to calibrate weighting E quipment and meters for Department Projects. A list of authorized companies is available from the Concrete Engineering Unit website. Calibration of weighing Equipment is required within three months prior to plant certification each calendar year. Calibrate weighing Equipment and perform spot checks in accordance with the Concrete Manual. D.1 Batching by Weight D.1.a Proportioning Methods Proportion concrete batch Materials by weight in a central plant or by volume as directed by the Engineer, in conjunction with the Concrete Engineer. D.1.b Weighing Equipment and Tolerances Weigh or measure concrete mixture ingredients using load cells or meters for Ready-mix and paving concrete to within the targeted batch weight in accordance with the following:

greater

In accordance with 1503, “Conformity with Contract Documents,” the Producer will make plant adjustments when out of tolerance values are reoccurring on the same day or over a period of 7 calendar days. D.1.c Batching of Mixing Water Separately measure each type of mixing water on Scales or water metering devices containing the following:

predetermined quantity

dating the time of the previous calibration and adjustment Calibration of the water meter is required within three months prior to plant certification each calendar year. Calibrate the water meter and perform spot checks in accordance with the Concrete Manual. Check the water meter for accuracy at least once each month as the W ork progresses.

D.1.d Batching of Cementitious Materials Weigh the cementitious Material independently of the Aggregates in separate compartments or on separate Scales. If the Contractor weighs the cement first and then separately records the weights of each individual cementitious Material, the Contractor may weigh the cementitious Materials cumulatively as approved by the Engineer, in conjunction with the Concrete Engineer. D.1.e Batching of Aggregates If the Contractor records each individual fraction weight of Aggregates separately, the Contractor may weigh Aggregates cumulatively as approved by the Engineer, in conjunction with the Concrete Engineer. D.1.f Admixture Proportioning If using two or more admixtures in a single concrete batch, add each admixture separately to prevent interaction of the different admixtures before mixing with other batch Materials. Agitate admixtures to ensure homogeneous concentrations in accordance with the manufacturer’s recommendations. Incorporate admixtures to the batch mix in liquid form. Maintain admixture solutions at a uniform concentration. Use the solution concentration and proportions designated by the manufacturer. If using a mechanical dispenser for proportioning Class I or Class II admixtures, provide a site gauge or meter. Have the admixture manufacturer check admixture dispensers yearly to determine accuracy and ensure unobstructed flow. D.1.g Fiber Proportioning Do not incorporate fiber packaging materials into the Concrete. The Engineer considers the following fiber addition methods acceptable on all jobs: Open bag and distribute fibers on Aggregate belt at Ready-mix Concrete plant. Open bag, break apart any fiber clumps, and introduce fibers into Ready-mix Concrete truck in a well-distributed manner. Any alternate methods to add fibers to the concrete mix must be submitted for acceptance by the Engineer and demonstrated by a successful trial placement. Ensure fibers are uniformly dispersed in the Concrete to avoid balling. Balling of fibers is defined as a 2-inch diameter or greater conglomerate of fibers at the point of placement. The Engineer will consider any balling more prevalent than 1 per load o f Concrete as unacceptable and may reject the load of concrete. D.2 Batching by Volume Proportion concrete for Bridge deck overlays by volume or as required by the Contract. If the Contractor calibrates the mixer for the specific batch Materials in use, the Contractor may proportion concrete on other items of Work by volume as approved by the Engineer in writing. The Engineer will approve methods and Equipment used in volumetric proportioning.

Determine Material proportions and calibration settings on the basis of 100 pounds of cementitious Material. Provide and use only sacked cement in the original mill containers unless the Contractor calibrates the mixer for the specific Materials in use. Do not use previously opened sacks. E Mixing Requirements The Engineer may check the water measuring Equipment for accuracy before mixing operations begin and at any other time the Engineer considers necessary. Mix concrete by one of the following methods:

Do not allow the mixing batch to merge or intermix with the subsequent dry batch during mixing. Discharge water remaining in the drums before batching. Mix concrete to provide a mixture that is homogeneous and uniform in color . The Engineer will reject concrete batches that show a marked variation in consistency or evidence of improper mixing as unacceptable Work in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” After completely mixing the concrete, either in a central plant mixer or truck mixer, continuously agitate while in transit to the point of placement until the concrete is discharged from the unit, unless otherwise allowed by the Engineer, in conjunction with the Concrete Engineer. If the mixing does not appear uniform, perform slump tests at the 15 percentage point and the 85 percentage points during unloading. If the results show a slump variation greater than 1 1/2 inch, stop Work and correct the mixing unit. Produce concrete in such quantity and at such a rate as proper placement and finishing will permit. Do not re-temper partially set concrete. Do not hand mix concrete. E.1 Mixing In Truck Mixer Charge the Materials into the truck mixer drum by introducing sufficient water before adding solid Materials. Perform charging operations without losing Materials. Leave the truck mixer at the plant site for a minimum of 5 minutes or 50 revolutions during the mixing period. Transport the concrete at agitating speed to the point of placement. F Certified Ready-mix Concrete Provide concrete from a certified ready-mix plant listed on the Concrete Engineering Unit website. Ensure the Producer performs Quality Control of concrete production and complies with the Department Certified Ready-mix Program. Provide batches for a delivered load of concrete in sizes of at least 1 cubic yard. The Engineer may reject Ready-mix Concrete delivered to the worksite that does not meet the specified requirements for delivery time, consistency, quality, air content, or other properties, as unacceptable Work in accordance with 1512, “Unacceptable and Unauthorized Work.”

F.1 Certified Ready-mix Plant Program The Producer will perform Quality Control (QC) under the certification program for Ready-mix Concrete plants in accordance with 2461.3F.3, “Contractor Quality Control (QC).” The Engineer will perform Quality Assurance (QA) as part of the acceptance process in accordance with 2461.3F.4, “Quality Assurance (QA).” F.1.a Plant Certification Prior to the production of Department concrete each construction season, a Department Certified Concrete Plant Technician, representing the Department, shall perform a thorough on-site inspection of the concrete plant with a Department Certified Concrete Plant Technician, representing the Producer. In order to obtain certification, complete the following:

before the on-site inspection with the Department representative.

representing the Producer, signs the Contact Report – ready mix certifying compliance with the certified ready-mix requirements and continual maintenance of the plant to assure that the plant can produce concrete meeting Department Specifications.

representing the Department, signs the Contact Report – ready mix signifying that the plant complies with all requirements before concrete production.

operations on Form 2163, Contact Report – ready-mix. Provide their email, cell phone number, and Department Technical Certification number.

Department pit number.

requirements of 2461.3F.2, “Certificate of Compliance.”

from Department’s website.

connection with availability for Department use, at the certified ready - mix plant.

Commercial Facility,” for the use of the plant technician in performing tests. The Department representative will submit the completed Contact Report – ready-mix and current Certificate of Compliance to the Concrete Engineer for final determination of certification. F.1.b Maintaining Plant Certification The Producer will maintain plant certification by:

plain sight at all times

Equipment changes and submitting to the Department

electronically at all times

Quality Control (QC)”

the plant site for 5 calendar years. F.1.c Certified Ready-mix Plant Decertification The Concrete Engineer, with coordination from the Engineer, may decertify the plant and halt production of concrete under any of the following conditions:

the completion of the Contact Report – ready-mix

Concrete”

F.2 Certificate of Compliance Provide a computerized Certificate of Compliance with each truckload of R eady-mixed Concrete at the time of delivery. The Department defines computerized to mean a document that records mix design quantities from load cells and meters. If the computer that generates the Certificate of Compliance malfunctions, the Engineer may allow the Contractor to finish any pours in progress if the Producer issues a handwritten or computer-generated Department Form 0042, Certificate of Compliance with each load. The Engineer will not allow the Producer to begin new pours without a working computerized Certificate of Compliance. Provide a computerized Certificate of Compliance that includes the following information:

or ounces per cubic yard

Table 2461.3-1 Standard Certificate of Compliance Labels Formula Letter Formula Standard Label a Ingredients (Aggregate, cementitious, water, admixture type) — Ingredient b Product Source (Department Standard Abbreviation) — Source c Total moisture factor (in decimals to 3 places) — MCFac d Absorption Factor (in decimals to 3 places) — AbsFac e Mix design oven dry (OD) weights, pound/cubic yard — OD f Absorbed moisture in the Aggregates, pound/cubic yard (e × d) Abs g Saturated surface dry (SSD) weights for Aggregates, pound/cubic yard) (e + f) SSD h Free moisture, pound/cubic yard (c - d) × e Free Mst i Target weights for one cubic yard of concrete, pound/cubic yard (g + h) cubic yard Targ j Target batch weights, pounds (cubic yard × i) Target k Actual batch weights, pounds — Actual NOTE: Actual cubic yards batched may vary due to differences in air content, weight tolerances, specific gravities of Aggregates, and other variables.

zero if no water is added)

Engineer, enter zero if no water is added)

Compliance plus any additions)

the Engineer to record the test results:

PS Sheet Number (PS##-###)

F.3 Contractor Quality Control (QC) The Producer’s daily responsibilities include the following:

Aggregates

are working properly. F.3.a Personnel The Producer will provide the following personnel:

requirements of 2461, “Structural Concrete.” The Quality Control Plant Technician shall hold a current Department Concrete Plant Certification.

and daily plant operations. The Quality Control Supervisor shall hold a current Department Concrete Plant Certification and is required to remain on-site during concrete production or have cellular phone availability.

Control Supervisor and the Certified Ready-mix Plant Program. F.3.b Sampling and Testing Take samples randomly in accordance with ASTM D3665, Standard Practice for Random Sampling of Construction, Section 5, at a rate defined in accordance with the Schedule of Materials Control. Perform sampling and testing in accordance with the Concrete Manual. The Engineer may oversee the QC sampling and testing process. Perform QC gradation and moisture testing at the certified ready-mix plant site. Use mechanical shakers for Sieve analysis. Provide Equipment and perform calibrations meeting the requirements of the following:

Coarse Aggregates

Moisture Content of Aggregate by Drying

Purpose

the Testing of Materials

F.3.c Aggregate Gradations Place concrete meeting the aggregate gradation requirements in the Work . Identify QC companion gradation samples with the following information :

If any gradation fails, immediately take second gradation. If the second gradation passes, resume testing as required. The Engineer will not allow the second gradation as a substitute for the next required QC gradation. If the second gradation fails, refer to Table 2461.5-1 for additional requirements. The Engineer will not allow a verification companion gradation as a substitute for a QC gradation. F.3.d Moisture Content Determine the moisture content using the oven-dry method in the Concrete Manual. Moisture probes to determine moisture content in the Aggregates are not allowed without the approval of the Concrete Engineer. Observe the batch person enter moisture contents into the batching system. Verify the moisture contents were entered correctly on the Certificate of Compliance. F.3.e Concrete Ready-mix Plant QC Workbook The Producer will complete and maintain the Concrete Ready-mix Plant QC Workbook in Real Time for all materials and sources incorporated into the concrete mix, using their full name for the diary and each test performed. The Producer’s designated Quality Control Supervisor will review and s ubmit to the Engineer and the Concrete Engineering Unit by the Tuesday immediately following the previous week’s production. F.3.f Aggregate Gradation Control Charts and Sample Log Complete the Aggregate gradation control charts in Real Time for each Aggregate size and Aggregate source by recording Producer QC gradations and verification companion gradation results. These results are included in the moving average calculation. Complete Sample Log in Real Time for all samples taken as follows:

and picked up by the Department F.3.g Signing the Certificate of Compliance The Producer’s Department Certified Plant technician will:

for accuracy

designated for Producer signature signifying agreement to the terms of this program and to certify that the Materials comply with the requirements of the Contract

Number next to the signature F.4 Quality Assurance (QA) The Engineer’s responsibilities each time the plant is visited includes the following:

Control Charts are accurate and up-to-date

interblending of the Aggregates

gradation and moisture tests when possible

Control

manner:

questionable, or unusual Activity is occurring during the plant visit perform the following:

diary.

resolution.

Concrete Engineering Unit when necessary. F.4.a Personnel The Department will provide Department Certified Concrete Plant Technicians to perform the duties of 2461.3F.4, “Quality Assurance (QA).” F.4.b Sampling and Testing The Engineer will:

Practice for Random Sampling Construction Materials, Section 5, at a rate defined in the Schedule of Materials Control

Manual

F.4.c Aggregate Gradations The Engineer will:

Aggregate size and source.

gradation result for compliance with lab/field tolerance in accordance with 2461.5A.1.b, “Lab Field Tolerance.” F.4.d Batch Weight Verification Each time the Engineer visits the plant, the Engineer will observe the actual water batched in a single load of concrete in accordance with the following:

recorded

water with the design water The Engineer will document the actual water batched on the Weekly Certified Ready-mix Plant Report. F.4.e Concrete Ready-mix Plant QA Workbook The Engineer will complete the Concrete Ready-Mix Plant QA Workbook in Real Time which includes all of the following documents:

in the field

performed in the field Submit to the Engineer and the Concrete Engineering Unit by the Thursday immediately following the previous week’s production. F.4.f Non-compliance with Certified Ready-mix Plant Program If the Engineer observes the Producer not complying with the requirements of the Certified Ready-Mix Plant Program, the Engineer may perform the following:

Engineer the list of observed deficiencies and provide a deadline to correct the non-compliance.

Contractor and Producer that concrete production is unauthorized in accordance with 1512, “Unacceptable and Unauthorized Work.” The Concrete Engineer will determine if the severity of the non-compliance results in decertification of the plant in accordance with 2461.3F.1.c, “Certified Ready- mix Plant Decertification.”

G Concrete Placement Assume full responsibility for the acceptable production, placement, finishing, and curing of concrete under the conditions prevailing, regardless of the restrictions imposed . Provide any artificial lighting and rain or cold weather protection necessary at no additional cost to the Department . Place concrete after the Engineer inspects and approves the foundation preparations, forms and falsework erection, placement of reinforcement steel, Materials, Equipment condition, and cold weather protection. Do not place concrete if portions of the base, subbase, or Subgrade Layer are frozen, or if the excessive moisture levels make the grade unstable. Maintain the surface temperature above freezing for forms, steel, and adjacent concrete that will come in contact with the poured concrete before concrete placement. Protect the concrete from freezing. Protect the concrete against damage from construction operations or traffic. The Engineer will evaluate any defects in concrete or concrete surfaces resulting from weather conditions, inadequate lighting, or other causes in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” G.1 Notice of Inspection Notify the Engineer at least 24 hours before beginning concrete production to allow the Engineer time to provide inspection forces needed for the Work and to approve preparations for concrete placement. If the Contractor fails to provide 24 hour notice, the Engineer may delay concrete placement and will consider any concrete incorporated into the W ork as unauthorized in accordance with 1512.2, “Unauthorized Work.” The Engineer will consider any delays to the Contract resulting from unauthorized Work as non-excusable in accordance with 1806.2C, “Non- Excusable Delays.” If the Producer needs to change plants during placement, notify the Engineer and obtain approval before changing the plant. G.2 Placement Temperatures The Contractor and Engineer will perform random sampling and testing in accordance with ASTM C172, Standard Practice for Sampling Freshly Mixed Concrete; ASTM C1064, Standard Test Method for Temperature of Freshly Mixed Hydraulic-Cement Concrete; and the Schedule of Materials Control. Maintain concrete temperature from 50°F to 90°F until placement. Unless Engineer approved cold weather protection Plans are in place, do not place concrete when the air temperature is either of the following at the point of placement:

within the following 24 hour period G.3 Delivery Requirements Place concrete into the Work in accordance with the following:

added at the plant at the manufacturer’s recommended dosage rates listed on

the APL. If the haul time does not facilitate mixing and placing the concrete within 90 minutes, test the concrete in accordance with 2461.3G.3.a, “Delivery Time Beyond 90 minutes” The Contractor may transport Type 3 concrete in non-agitating Equipment if the concrete is discharged within 45 minutes of batching. Batch time starts when the batch plant or the transit mix truck adds the cement to the other batch Materials. G.3.a Delivery Time Beyond 90 minutes If the haul time does not facilitate mixing and placing the concrete within 90 minutes, follow the procedures set out in this subsection for each proposed concrete mix to extend the delivery time to 120 minutes. Extending the delivery time beyond 120 minutes will require additional testing at 30-minute intervals up to the maximum desired delivery time as directed by the Concrete Engineer. The Concrete Engineer will allow trial batching at an AASHTO accredited laboratory to pre-qualify the concrete mix in accordance with 2461.3G.3.a(1), “Lab Trial Batching.” The Concrete Engineer may waive the lab trial batching requirement and allow only field trial batching of the proposed mix to extend the delivery time on an individual Project in accordance with 2461.3G.3.a(2), “Field Trial Batching.” Upon completion of the trial batching, provide the trial batching test results and proposed mix design to the Concrete Engineer. Submit the Contractor mix design in accordance with 2461.2E.2.b, “Contractor Designed Concrete Mixes.” Final approval of the mixture is based on satisfactory field placement and performance. G.3.a(1) Lab Trial Batching Contact the Concrete Engineering Unit a minimum of 2 Calendar Days before trial batching. Ensure the admixture manufacturer’s technical representative is present during the trial batching. Laboratory trial batch and test the proposed mix in accordance with the following:

measure the slump, air content, unit weight, and temperature immediately after batching, at 90 minutes and at 120 minutes

90 minutes and at 120 minutes (sets of 3). Test all of the cylinders for compressive strength at 28 Calendar Days

testing at 90 minutes and at 120 minutes (sets of 5). Determine the hardened air content (ASTM C457, Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete) at a minimum of 7 Calendar Days on 2 samples representing 90 minutes and 2 samples representing

120 minutes. Provide Department with the other 6 samples for testing at their discretion. Retain any hardened concrete test specimens for a minimum of 90 days for Department to examine at their discretion. Once accepted by the Concrete Engineer, the Department will consider the laboratory trial batching acceptable for use for 5 years; unless the Concrete Engineer determines the Material sources have changed significantly since the initial laboratory testing and acceptance. G.3.a(2) Field Trial Batching Submit a QC Plan for extending the delivery time beyond 90 minutes for review and approval to the Concrete Engineer a minimum of 2 Calendar Days before field trial batching. The QC Plan includes the proposed Materials, batching sequences, anticipated timeline for admixture and/or water adjustments at the P roject Site, delivery method, and anticipated typical travel time to Project Site. The Contractor must demonstrate to the Engineer the ability to properly mix, control, and place the concrete in accordance with the proposed QC Plan and the Contract. Perform field trial batching on the proposed mix in the presence of the Engineer in accordance with the following:

same Materials and methods intended for use when supplying concrete placed into the permanent Work

around the yard or on the Roadway; and maintain the drum speed at 5 to 7 revolutions per minute for the entire 120 minutes

temperature after making all admixtures and water adjustments to the concrete mixture at 90 minutes and 120 minutes

90 minutes and at 120 minutes (sets of 3). Test all of the cylinders for compressive strength at 7 Calendar Days

testing at 90 minutes and at 120 minutes (sets of 2). Determine the hardened air content (ASTM C457, Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete) at a minimum of 7 Calendar Days on 1 sample representing 90 minutes and 1 sample representing 120 minutes. Provide Department with the other 2 samples for testing at their discretion. Retain any hardened concrete test specimens for a minimum of 90 Calendar Days for Department to examine at their discretion

with the approval of the Engineer

G.4 Field Adjustments Mix the load a minimum of 5 minutes or 50 revolutions at mixing speed after addition of admixture or additional mixing water. G.4.a Water Adjustments The Engineer will allow water adjustments in accordance with the following:

Certificate of Compliance G.4.b Water Adjustments for Concrete Placed by the Slip-Form Method The Engineer will allow water adjustments for all grades of concrete placed by the slip-form method, except Grade A paving concrete, in accordance with the following:

Certificate of Compliance G.4.c Admixture Adjustments Approved admixture additions are allowed within 90 minutes from the initial batch time stated on the Certificate of Compliance. If the load of concrete has no available water to add, or the load is greater than 60 minutes old, the Engineer will allow one admixture adjustment diluted with up to 2 gallons of water. G.4.d Consistency and Air Content Adjustments The Engineer will test the concrete for compliance with 2461.3G.7, “Consistency,” and 2461.3G.8, “Air Content,” in accordance with the following:

continue verification testing in accordance with the Schedule of Materials Control

any Quality Control testing before the Engineer performs a final test. Acceptance or rejection of the truck is based on the Engineer’s final test result

items (1) and (2) above

the Engineer will reduce their verification testing rate to once per truck for acceptance for the remainder of the pour For concrete mixes 3U17A and 3U18, allow mix to hydrate 5 minutes before slump test to assure cement is saturated. G.5 Concrete Strength For all cast-in-place concrete as specified in 2461, “Structural Concrete,” including HE concrete, place concrete meeting the strength requirements of Table 2461.2-6 and Table 2461.2-7 unless otherwise specified in the Contract into the Work. Unless otherwise included in the Plans, HE concrete requires approval of the Engineer before incorporation into the Work.

G.5.a Concrete Cylinder Requirements The Contractor and Engineer will perform random sampling and testing in accordance with ASTM C172, Standard Practice for Sampling Freshly Mixed Concrete; ASTM C31, Standard Practice for Making and Curing Concrete Test Specimens in the Field; ASTM C39, Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens; and the Schedule of Materials Control. Anyone performing concrete strength testing of cylinders is required to hold one of the following current certifications:

Anyone fabricating concrete cylinders or beams is required to hold either a current ACI Field 1 Technician Certification or a Department Field 1 Technician Certification. G.5.b Standard Strength Cylinders All standard strength cylinders have a minimum 28-Calendar Day compressive strength requirement unless modified elsewhere in the Contract. The Engineer will perform the following for standard strength cylinders:

Materials Control or as modified in the Contract

concrete

including the results for air content, slump (if required), concrete, and air temperature testing from the same load G.5.b(1) Curing Standard Strength Cylinders Properly cure standard strength cylinders during each specified curing period in accordance with the following:

up to 48 hours

the initial curing site and delivery to the laboratory for final curing, Intermediate curing period is up to 7 Calendar Days from the day of casting. Cure the standard strength cylinders in the Contractor provided moist curing environment

laboratory lasts a minimum of 21 Calendar Days G.5.b(2) Moist Curing Environment At least 24 hours before concrete placement, provide moist curing environment(s) of adequate size and number, including ancillary E quipment and Materials, necessary to maintain moist curing environment(s) in accordance with ASTM C31, Standard Practice for Making and Curing Concrete Test Specimens in the Field and 2031, “Field Office and Laboratory,” and the following:

For each separate moist curing environment:

recording device that records the daily maximum and minimum ambient temperatures for the previous 7 Calendar Days.

strength cylinders or beams in an ambient temperature range from 60°F to 80°F.

cylinders with lids in water maintained at a temperature from 60°F to 80°F. The Engineer will monitor the daily temperatures of the curing environments. Department monitoring does not relieve the Contractor of the responsibility to maintain the water temperature as specified herein. If the Contractor fails to comply with the requirements shown here-in, the Engineer may delay concrete placement and will consider any concrete incorporated into the Work as unauthorized in accordance with 1512.2, “Unauthorized Work.” The Engineer will consider any delays to the Contract resulting from unauthorized Work as non-excusable in accordance with 1806.2C, “Non-Excusable Delays.” G.5.b(3) Transporting Cylinders After the initial curing period, the Engineer will both transport and further cure the cylinders using intermediate curing or final curing conditions. The Engineer will transport the cylinders from the initial curing site in accordance with the following:

(Grade MC) a minimum of 16 hours after casting

after casting

least 12 hours after casting

molds, or by other methods to prevent moisture loss

in the moistened condition at ambient temperature of 60°F to 80°F G.5.b(4) Testing Cylinders The Engineer will perform compressive strength testing on the standard strength cylinders in accordance with ASTM C39, Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens during the Departments normal laboratory operating hours. The Department will report the results in accordance with the Laboratory Manual.

G.5.c Field Control Strength Cylinders The Engineer will use field control cylinders to determine when the sequence of construction operations is dependent upon the rate of concrete strength development. The Engineer will cast field control cylinders to determine when the concrete attains the required strength for desired field control limitations. In lieu of field control cylinders, the Engineer will allow the Contractor to submit a strength-maturity relationship curve for use in accordance with 2461.3G.6, “Estimating Concrete Strength by the Maturity Method.” The Engineer will perform the following for field control strength cylinders:

responsible for any additional field control cylinders

or section of concrete in accordance with 2461.3G.5.b, “Standard Strength Cylinders,” Note (2)

including the results for air content, slump (if required), concrete, and air temperature testing from the same load G.5.c(1) Curing Field Control Cylinders Cure field control concrete cylinders in the same location and under the same conditions as the concrete Structure or unit involved. The Engineer will allow “Match Curing of Concrete Test Specimens” method in accordance with AASHTO R72 Standard Practice for Match Curing of Concrete Test Specimens, modified as follows:

heating system capable of maintaining concrete cylinders at a temperature no greater than 5°F above the temperature of the concrete at a specific location in the member. A satisfactory system to continually monitor the concrete temperatures may include a temperature sensor in the concrete Structure or unit involved, a controller, special insulated cylinder molds with built-in heating systems, and a temperature sensor in the molds.

monitoring system fails, the Engineer will not accept field control cylinder results. G.5.c(2) Testing Cylinders The Engineer will perform compressive strength testing on the field control cylinders in accordance with ASTM C39, Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens during the Departments normal laboratory operating hours. If Project scheduling requires testing outside of the Department’s laboratories normal operating hours or the Department’s nearest laboratory is greater than 30 miles from the Project, provide certified and calibrated hydraulic cylinder-testing machine within 30 miles of the Project and at a location approved by the Engineer. Test the field control cylinders in the

presence of the Engineer in accordance with ASTM C39, Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens . G.5.d Strength Specimens for Concrete Paving Use flexural beams to determine strength or provide cylinders approved by the Engineer. Cast standard beams or cylinders for testing at 28 Calendar Days. Cast a sufficient number of field control beams or field control cylinders to determine when the concrete attains the required strength for desired control limitations. Cure the standard beams or cylinders in accordance with 2461.3G.5.b(1), “Curing Standard Strength Cylinders,” and 2461.3G.5.b(2), “Moist Curing Environment,” except standard beams are cured in intermediate curing conditions until broken at 28 Calendar Days. Cure the field control beams or cylinders in the same location and under the same conditions as the concrete pavement. The Engineer will test the flexural beams and record the results on Form 2162, Concrete Test Beam Data. If using cylinders, the Engineer will submit cylinders and a completed identification card to the Department’s laboratory. G.5.e Concrete Compressive Strength For purposes of the Work in section 2461.3G.5, “Concrete Strength,” the Department defines a strength test as the average strength of 3 cylinders fabricated from a single sample of concrete and cured in accordance with 2461.3G.5.b , “Standard Strength Cylinders.” The maximum allowable range between the individual cylinders in a strength test is 350 psi. The Department will remove all individual cylinder strengths that are more than 350 psi below the highest individual cylinder strength and recalculate the strength. The Engineer will review standard strength test results for acceptance in accordance with Table 2461.3-2 and 2461.5A.2, “Concrete Strength Non-Conforming Material.” Table 2461.3-2 Acceptance Criteria for Standard 28-Calendar Day Cylinders Single Strength Tests Moving average of 3 consecutive strength tests* f’c ≤ 5000 psi > (f’c – 500 psi) ≥ f’c f’c > 5000 psi > 0.90 * f’c ≥ f’c * If a Project does not establish a moving average of 3 consecutive strength tests, use the average of 2 strength tests to determine acceptance. If there is only a single strength test, contact the Concrete Engineer for recommendation.

G.6 Estimating Concrete Strength by the Maturity Method The Engineer will allow the maturity method to determine development of concrete strength to open to traffic loading or form removal. Use of this method requires the establishment of a relationship between concrete strength and the computed maturity index (using the Nurse-Saul method) for a specific concrete mixture. Use this method, in accordance with this Specification and the “Estimating Concrete Strength by the Maturity Method” procedure available from the MnDOT Concrete Engineering website to estimate the in -place strength of the concrete. G.6.a Development of Strength-Maturity Relationship The Engineer will allow development of the maturity curve in a laboratory, at the concrete plant, or at the Project Site. Determine the strength development criteria based on the type of concrete in accordance with the following:

Equipment and Traffic”

3000 psi is required Until an acceptable strength-maturity relationship (maturity curve) is established and approved by the Engineer, use concrete beams or cylinders to open to traffic loading or form removal. G.6.a(1) Procedure Develop the strength-maturity relationship (maturity curve) to estimate concrete strength in accordance the “Estimating Concrete Strength by the Maturity Method” procedure available from the MnDOT Concrete Engineering Website and the following:

beams or cylinders to embed temperature sensors.

Maturity-Strength Development form.

specified in Table 2461.3-3 for the type of concrete Work.

Table 2461.3-3 Chronological Testing Ages of Strength Specimens Type of Concrete Testing Ages* Concrete Pavement as defined in 2301, “Concrete Pavement” Test at least 2 sets of strength specimens before and the remaining sets after the anticipated opening strength Normal Strength Concrete as defined in 2461, “Structural Concrete” 1, 3, 7, 14, and 28-Calendar Days High-early (HE) Concrete as defined in 2461, “Structural Concrete” 12 hours, 1, 2, 7 and 28-Calendar Days Ultra High-early (UHE) Concrete as defined in 2302, Concrete Pavement Rehabilitation” 3, 4 and 8 hours, 1 and 14- Calendar Days * The Contractor may adjust the testing ages if approved by the Engineer, in conjunction with the Concrete Engineer. G.6.a(2) Equipment Provide the following Equipment for determining the maturity:

with a secure means of collecting, measuring, recording, and storing temperature data that is unalterable

curve and other concrete making and testing Equipment G.6.a(3) Estimating In-Place Strength Using Maturity Place concrete maturity meters or temperature sensors within the concrete in accordance with Table 2461.3-4. Table 2461.3-4 Maturity Meter or Temperature Sensor Placement and Frequency Maturity Application Placement Frequency Concrete Paving Embed at approximately mid-depth and approximately 18 (but no less than 12) inches from the edge of the pavement. Place one for each day within the last hour of placement. Place additional sensors as necessary. Full Depth Concrete Pavement Repairs Embed at approximately mid-depth and approximately 18 (but no less than 12) inches from the edge of the pavement. Place one for each day within the last hour of placement. Place additional sensors as necessary. Partial Depth Concrete Repairs Embed at least 2 inches from the surface. Place one for each day within the last hour of placement. Place additional sensors as necessary. Sidewalk, Driveway Entrances, Curb and Gutter Embed at approximately mid-depth and approximately 18 (but no less than 12) inches from the edge of the pavement. Place one for each day within the last hour of placement. Place additional sensors as necessary. Concrete Structures Attach to the reinforcing steel near the edge of the exposed surface using a non- metallic fastener. Place at least 2 for each concrete element.

The computed maturity results from each sensor will only apply to concrete placed under the following conditions:

test location

after placement of the sensor

location Record the maturity index (or temperature readings and calculate the maturity index) on the Maturity-Field Data form or as approved by the Concrete Engineer. G.6.b Opening to Traffic Loading or Form Removal Prior to opening the concrete to traffic loading or removal of the forms, submit the maturity index results to the Engineer. The Engineer will review and verify the maturity index has reached the required TTF of the maturity curve developed for that concrete mix. G.6.c Validation of Strength-Maturity Relationship for Continued Use When utilizing the maturity method on the Project, perform a strength- maturity test for each mix used to ensure the concrete strength correlates with the current maturity-strength relationship (maturity curve) as follows:

casting for the validation testing.

curing, and testing three (3) beams or cylinders plus one additional beam or cylinder to embed the sensor. Cast the validation specimens at the concrete plant or at the Project Site.

perform a validation strength-maturity test on the first day of concrete placement.

batching plant, perform a validation strength-maturity test once every 15 Calendar Days during plant production.

greater than 30 Calendar Days before the start of construction or has not been validated for 30 Calendar Days, perform a validation strength-maturity test on the first day of concrete placement. The Concrete Engineer will allow a single validation strength-maturity test fabricated at the concrete plant to validate a maturity curve used on multiple Projects. Validation strength-maturity tests fabricated at the Project Site only validate the maturity curve for that Project.

curing environment for the specimens in accordance with the “Estimating Concrete Strength by the Maturity Method” procedure available from the MnDOT Concrete Engineering website.

maturity value determined to represent the opening, loading or form removal strength criteria. Record the results of the tests on the Concrete Maturity-Strength Validation form and provide to the Engineer within 24 hours of the test completion.

damaged due to handling), discard the specimen. If an individual specimen is greater than 10 percent for cylinders or 15 percent for beams outside the average of three specimens, consider the specimen defective and discard. When two of the specimens are defective, evaluate a new batch, unless additional acceptable specimens are available. The Engineer may direct additional validation testing as necessary. The Engineer will review the validation strength-maturity test results and determine if the validation testing confirms the maturity curve in accordance with Table 2461.3-5. Table 2461.3-5 Evaluation of Validation Strength-Maturity Test Results If the validation strength-maturity test falls: Result Action Within the 10 percent limits of the maturity curve Maturity curve validated Continue using the current maturity curve > 10 percent higher than the maturity curve The Engineer will not consider the maturity curve validated, but will continue to allow use of the maturity curve Develop a new maturity curve at the discretion of the Contractor > 10 percent lower than the maturity curve The maturity curve will no longer be acceptable

method for that concrete mix until a new maturity curve is developed G.6.d Changes in Concrete Mixture Perform a validation strength-maturity test in accordance with 2461.3G.6.c, “Validation of Strength-Maturity Relationship for Continued Use,” if any of the following changes occur:

Evaluate validation strength-maturity test results in accordance with Table 2461.3-5. G.6.e Maturity Meter Calibration Calibrate maturity meters yearly to ensure proper operation and temperature sensing in accordance with the “Estimating Concrete Strength by the Maturity Method” procedure available from the MnDOT Concrete Engineering website. G.7 Consistency Place concrete meeting the slump requirements in the Work.

The Contractor and Engineer will perform random sampling and testing in accordance with ASTM C172, Standard Practice for Sampling Freshly Mixed Concrete; ASTM C143, Standard Test Method for Slump of Hydraulic-Cement Concrete; ASTM C1611, Standard Test Method for Slump Flow of Self-Consolidating Concrete; and the Schedule of Materials Control. The Engineer will test the concrete for consistency using the slump test during the progress of the Work. The Engineer may reject concrete batches with consistencies outside of the slump range limits in Table 2461.2-5, Table 2461.2-6 and Table 2461.2-7. If any test shows the slump outside of the slump range requirements, the Engineer will reject the concrete represented by that test. In order to bring the mixture back into the slump range requirements, the Engineer will allow adjustments to the concrete in accordance with 2461.3G.3, “Delivery Requirements” and 2461.3G.4, “Field Adjustments.” Adjust the slump not to exceed the slump range allowed to optimize both placement and finishing. Contact the Engineer if encountering unusual placement conditions that render the maximum slump unsuitable. G.7.a Concrete Placed by the Slip-Form Method Place concrete that does not slough and is adequately consolidated at a slump value that optimizes placement for the designated mixture and in accordance with 2461.3G.4, “Field Adjustments.” G.8 Air Content Place Type 3 concrete meeting the air content requirements in the Work. The Contractor and Engineer will perform random sampling and testing in accordance with ASTM C172, Standard Practice for Sampling Freshly Mixed Concrete; ASTM C231, Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method; and the Schedule of Materials Control. Maintain the air content of Type 3 general concrete at the specified target of 6.5 percent (+2.0 percent and −1.5 percent) of the measured volume of the plastic concrete in accordance with 1503, “Conformity with Contract Documents,” unless otherwise modified in the Contract. Maintain the air content of Type 3A Grout at the specified target of 10.0 percent (-2.0 percent and no maximum). Test the air content at the point of delivery (eg., end of concrete chute) unless otherwise specified in the Contract. Make any adjustments immediately to maintain the desired air content. G.9 Allowable Testing Tolerances Allowable tolerances are based on the results from two different testers and two different pieces of Equipment from the same sample. Perform the test within the allowable tolerances in accordance with Table 2461.3-6.

Table 2461.3-6 Allowable Testing Tolerances Test Allowable Tolerance Air content, percent volume of concrete 1.0 percent Average slump < 4 inches 1.0 inch Average slump 4 inches – 6 inches 1.5 inches Average slump > 6 inches 2.0 inches Unit weight, per cubic foot, calculated to an air-free basis 1.0 pound/cubic foot Compressive strength 3,000 psi – 8,000 psi, average of 3 tests 500 psi

2461.4METHOD OF MEASUREMENT

The Engineer will measure fresh concrete produced as required by the C ontract by the theoretical volume. The Engineer will deduct accountable waste from the concrete measurement. The Engineer will measure concrete mixtures on the basis of the dimensions of the S tructure shown on the Plans. If the Plans do not include a Contract Item for concrete used in miscellaneous items, include the cost of the concrete with the relevant Contract Items.

2461.5BASIS OF PAYMENT

The Department will include the cost of the Certified Ready-mix Plant Program with other relevant Contract Items. The Contract cubic yard price for Concrete Mix No. ___ includes the cost of production, placement, finishing, curing, and protection of concrete. A Monetary Deductions The Department must apply Incentives and Disincentives and may apply monetary deductions for Structural Concrete. The amounts of these adjustments are deemed reasonable. A.1 Certified Ready-mix Concrete, Acceptance of Concrete Materials Only place concrete meeting the Materials requirements in the Work. If the Contractor places concrete not meeting the Materials requirements into the Work, the Engineer will not accept non-conforming concrete at the Contract Unit Price. A.1.a Aggregate Gradation (Does not apply to Job Mix Formulas) The Engineer will base Material acceptance on individual and moving average test results in accordance with Table 2461.5-1 and the following:

verification samples result in a variation between the Producer and the Engineer greater than that set forth in Table 2461.5-3, the Engineer will substitute QA and/or verification test results into the moving average calculation to determine acceptance.

test results, the Engineer will review in accordance with 1503, “Conformity with Contract Documents.”

moving average gradation failure.

beginning with the first individual gradation test within the moving average failure and ending with the first passing individual gradation test after the moving average failure.

placed, the Engineer will apply the monetary deductions outlined in Table 2461.5-2.

Engineer will only reduce the price based on a single monetary deduction. Table 2461.5-1 Acceptance Criteria for Aggregate Gradations

Contractor Action Within Gradation Limits of 3126, “Fine Aggregate for Concrete” or 3137, “Coarse Aggregate for Concrete” Outside of Gradation Limits in 3126, “Fine Aggregate for Concrete” or 3137, “Coarse Aggregate for Concrete.” Individual gradation test Continue testing as required

required

and contact Engineer

a passing gradation and continue testing as required ǁ Moving average of 4 consecutive tests* Continue testing as required

Material

a passing gradation

yards until the moving average is within the gradation limits * If any Aggregate size or source does not establish a moving average of 4 consecutive tests, use the average of tests taken to determine acceptance. ǁ The Engineer may increase the testing rates if gradation issues persist.

Table 2461.5-2 Moving Average Gradation of Specification Sieves Total Concrete Quantity Cubic Yards Lump Sum Monetary Deduction 0 to 8 $125.00 > 8 to 15 $250.00 > 15 to 20 $375.00 > 20 $500.00 or $5.00 per cubic yard, whichever is greater

A.1.b Lab Field Tolerance If the gradation tests on split samples from Quality Control or verification samples result in a variation between the Producer and the Engineer greater than that set forth in Table 2461.5-3, the parties shall follow the procedures for test result dispute resolution available from the Laboratory Manual. Table 2461.5-3 Allowable Variations on Percent Passing Sieves Sieve Size Allowed Percentage 2 inches – 1 inch ± 8 3/4 inch – 3/8 inch ± 6 No. 4 – No. 30 ± 4 No. 50 ± 3 No. 100 ± 2 No. 200 ± 0.6 A.1.c Coarse Aggregate Quality The Engineer, in conjunction with the Concrete Engineer, will determine adjusted Contract Unit Prices for coarse Aggregate quality failures in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” A.1.d Cementitious Materials The Engineer, in conjunction with the Concrete Engineer, will determine adjusted Contract Unit Prices for cementitious failures in accordance with 1512, “Unacceptable and Unauthorized Work.” A.1.e Admixtures The Engineer, in conjunction with the Concrete Engineer, will determine adjusted Contract Unit Prices for admixture failures in accordance with 1512, “Unacceptable and Unauthorized Work.” A.2 Concrete Strength Non-Conforming Material If the Contractor places concrete not meeting the strength requirements of 2461.3G.5.e , “Concrete Compressive Strength,” into the Work, the Engineer may not accept nonconforming concrete at the Contract Unit Price. The Engineer will evaluate non-conforming strength results in accordance with the following: A.2.a Strength Test ≤ 500 psi Below f’c If any strength test result shows a strength ≤ 500 psi below f’c and is not deficient due to erroneous/invalid strength tests as defined in 2461.5A.2.d , “Moving Average Below f’c,” no additional investigation will occur and the Engineer will include the low strength test result in the moving average. A.2.b Strength Test > 500 psi Below f’c If any strength test result shows a strength > 500 psi below f’c and is not deficient due to erroneous/invalid strength tests as defined in 2461.5A.2.d , “Moving Average Below f’c,” the Engineer, in conjunction with the Concrete Engineer, will investigate to determine if the concrete has attained the critical load-carrying capacity. The investigation may consist of, but is not limited to reviewing the following:

Method for Rebound Number of Hardened Concrete), Penetration Resistance (ASTM C803, Standard Test Method for Penetration Resistance of Hardened Concrete), or other method approved by the Concrete Engineer

If it is determined that the concrete represented by the standard strength test has attained the critical load carrying capacity, the Engineer will include the strength test in the moving average calculation. If it is determined that the concrete has not attained the critical load carrying capacity, the Engineer will direct the Contractor to remove and replace concrete in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” The Contractor may dispute the remove and replace order within 7 Calendar Days of written notification by the Engineer. If the Contractor disputes the order, follow the dispute resolution coring procedure in accordance with 2461.5A.2.c, “Dispute Resolution Coring for Strength Test Failure.” A.2.c Dispute Resolution Coring for a Strength Test Failure The Engineer and Contractor will mutually agree on an independent third-party to core and test the concrete in accordance with ASTM C42, Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete” and the following:

independent third-party to core.

Days of notification of the low strength concrete.

The Engineer, in conjunction with the Concrete Engineer, will review the core test results and evaluate in accordance with Table 2461.5-4, providing other concrete tests meet requirements.

Table 2461.5-4 Evaluation of Core Test Results Core (average of 3 cores) Test Results Engineer considers concrete Cost of Coring and Testing Resolution ≥ 85 percent of f’c and no individual core is < 75 percent of f’c Acceptable to remain in place Department No monetary deduction for single strength test failure. < 85 percent of f’c Unacceptable Contractor Remove and replace concrete in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work,” as directed by the Engineer, in conjunction with the Concrete Engineer. A.2.d Moving Average Below f’c If the moving average of 3 consecutive strength tests is less than the required f’c, the Concrete Engineer will review the strength test results and determine if a new mix design is required in accordance with Table 2461.2-6 or Table Table 2461.2-7. The Concrete Engineer in conjunction with the Engineer will remove any strength test results from the moving average if the following occurs:

to improper handling, curing, or testing of the cylinder.

impact the moving average calculation.

in place. For the quantity of non-conforming concrete not meeting the moving average of 3 consecutive strength tests, the Engineer will make determinations regarding the disposition, payment, or removal of the concrete in accordance with Table 2461.5-5.

Table 2461.5-5 All Concrete Grades Moving average of 3 consecutive strength tests Monetary Deductions for Moving Average Failure * > 96.0 percent of f’c No deductions for the Materials placed as approved by the Engineer. 91.0 percent to 96.0 percent of f’c $20.00 per cubic yard or 10 percent of the Contractor-provided invoice for quantity represented by test that brought moving average into non-conformance. ≥ 87.5 percent and < 91.0 percent of f’c $50.00 per cubic yard or 25 percent of the Contractor-provided invoice for quantity represented by test that brought moving average into non-conformance. < 87.5 percent of f’c Remove and replace concrete in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work,” as directed by the Engineer. If the Engineer, in conjunction with the Concrete Engineer, determines the concrete can remain in-place, the Engineer will adjust the concrete at a reduction of $100.00 per cubic yard or 50 percent of the Contractor-provided invoice for quantity represented by test that brought moving average into non-conformance. A.3 Consistency, Non-conforming Material If the Contractor places concrete not meeting the slump requirements into the W ork, the Engineer will not accept non-conforming concrete at the Contract Unit Price. For the quantity of non-conforming concrete not meeting the required slump, the Engineer will make determinations regarding the disposition, payment, or removal of the concrete in accordance with Table 2461.5-6 and Table 2461.5-7. Table 2461.5-6 All Concrete Grades > 1 inch slump Outside of Slump Range Monetary Deduction Below slump range * No deduction for Materials placed as approved by the Engineer ≤ 1 1/2 inches above slump range $20.00 per cubic yard or 10 percent of the Contractor-provided invoice for quantity represented by the Materials placed > 1 1/2 inches above slump range $50.00 per cubic yard or 25 percent of the Contractor-provided invoice for quantity represented by the Materials placed * The Engineer will not reduce Contract Unit Price for low slump concrete placed with the slip-form method as approved by the Engineer.

Table 2461.5-7 Low Slump Concrete from 1/2 inch to 1 inch Outside of Slump Range Monetary Deduction Below slump range * No deduction for Materials placed as approved by the Engineer ≤ 1/2 inches above slump range $20.00 per cubic yard or 10 percent of the Contractor-provided invoice for quantity represented by the Materials placed ≥ 3/4 inches above slump range $50.00 per cubic yard or 25 percent of the Contractor-provided invoice for quantity represented by the Materials placed *The Engineer will not reduce Contract Unit Price for low slump concrete placed with the slip-form method as approved by the Engineer.

A.4 Air Content, Non-conforming Material If the Contractor places Type 3 concrete not meeting the air content requirements into the Work, the Engineer will not accept non-conforming concrete at the Contract Unit Price. For the quantity of non-conforming concrete not meeting the required air content, the Engineer will make determinations regarding the disposition, payment, or removal in accordance with Table 2461.5-8. Table 2461.5-8 All Concrete (Target Air Content 6.5 percent) Air Content percent Monetary Deduction > 10.0 $50.00 per cubic yard or 25 percent of the Contractor-provided invoice for quantity represented by the Materials placed. >8.5 – 10.0 $20.00 per cubic yard or 10 percent of the Contractor-provided invoice for quantity represented by the Materials placed. 5.0 – 8.5 The Engineer will pay 100 percent of the Contract Unit Price for the concrete represented, for Material placed as approved by the Engineer. >4.0 – <5.0 $50.00 per cubic yard or 25 percent of the Contractor-provided invoice for quantity represented by the Materials placed. >3.5 – ≤4.0 The Engineer, in conjunction with the Concrete Engineer will determine the concrete suitability for the intended use in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” This may include testing on the hardened concrete as required by the Engineer, in conjunction with the Concrete Engineer. ≤ 3.5 Remove and replace concrete in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work,” as directed by the Engineer. This may include testing on the hardened concrete as required by the Engineer, in conjunction with the Concrete Engineer. If the Engineer, in conjunction with the Concrete Engineer, determines the concrete can remain in-place, the Engineer may not pay for the concrete and may require coating with an approved epoxy penetrant sealer from the APL.

B Schedule The Department will pay for structural concrete on the basis of the following schedule: Item No. Item Unit

2461.507 Concrete Mix No ___ cubic yard