505Bridge Deck Concrete Wearing Surface

505.10.1 Description. This work shall consist of constructing a low slump, concrete wearing surface on a

prepared surface in accordance with this specification, as shown on the plans or as directed by the engineer.

505.10.2 Material. All material shall be in accordance with Division 1000, Material Details, and specifically as

follows: Item Section Type I or II Cement 1019 Air-Entraining Admixture 1054 Water Reducing Admixture 1054 Burlap 1055 Polyethylene Sheeting 1058 Water 1070

505.10.2 1 Coarse aggregate shall be an approved crushed limestone, crushed quartzite, flint chat from the

Joplin area or porphyry in accordance with Sec 1005.2, Gradation E, except that the sum of percentages of all deleterious substances shall not exceed one percent and the percentage of deleterious substances shall not exceed the following values: Item Percent by Weight Deleterious Rock 1.0 Shale and Pyrite 0.2 Chert in Limestone 0.5 Other Foreign Material 0.1

505.10.2 2 Gradation D may be used when the plan thickness of the bridge deck wearing surface is 3 inches or

greater.

505.10.2 3 Fine aggregate shall be in accordance with Sec 1005.3 and shall be Class A sand in accordance with

Sec 501.

505.10.2 4 Pozzolanic material or Portland pozzolan cements shall not be used.

505.10.3 Concrete Mixture.

505.10.3 1 The contractor shall submit a mix design to Construction and Materials meeting the following

properties: Property Requirement Air Content, percent, min. 5.0 Slump, inches 0.5 (± 0.5) Fine Aggregate, % of total aggregate by absolute volume50 Cement Content, lb./cy 818 to 827

505.10.3 2 The cement content and percent fine aggregate shall not be changed. If total mixing water, including

free water in aggregate and liquid admixtures, varies from design mixing water to cause a change in batch volume of more than two percent, a new mix design will be required.

505.10.3 3 A Type A water-reducing admixture will be required.

505.10.3 4 During placement, the mixture shall be compacted to no less than 98 percent of the standard density.

505.10.4 Testing.

505.10.4 1 Slump will be determined in accordance with AASHTO T 119. The sample for slump testing will be

taken at the point of placement in the structure.

505.10.4 2 Air content will be determined by the pressure method in accordance with AASHTO T 152.

505.10.4 3 When required, standard density, unit weight, will be determined in accordance with AASHTO T

121. Standard density will be determined for at least each two hours of concrete production or any time significant fluctuations occur within the range of air content or slump.

505.10.4 4 Compressive strength will be determined from at least two 6 by 12 inch cylinders or from at least

three 4 by 8 inch cylinders prepared in accordance with AASHTO T 23 and tested in accordance with AASHTO T 22. One set consisting of two cylinders will be made for 28-day compressive strength from each day's production. Cylinders made for determining when to permit traffic will be made at a frequency determined by the engineer, and will be cured in the near vicinity and in the same manner as the bridge deck.

505.10.4 5 Concrete taken as a sample for testing slump and air content shall be wasted and shall not be placed

in the deck. If air content or slump test results are not in accordance with specifications, any concrete represented by those tests and any concrete in the mixer chute shall be wasted, and the necessary adjustments shall be made in the mix design or proportioning devices.

505.10.4 6 When concrete density is specified, in-place density of plastic concrete will be determined in

accordance with MoDOT Test Method TM 36. In-place density will be determined at a minimum passing test rate of one per 100 square yards or three per continuous pour, whichever is greater. A nuclear gauge correction factor will be determined at least once for each day of concrete production. Work bridges spanning the plastic concrete shall be provided by the contractor to permit performing nuclear density tests.

505.10.5 Mixing.

505.10.5 1 Concrete shall be mixed in accordance with Sec 501.

505.10.5 2 Mixing time for rotating paddle type mixers shall be a minimum of 60 seconds after all ingredients

have been added. All batches shall be mixed approximately the same length of time. Material for a batch of concrete shall not be placed in the mixing drum until the material for the previous batch has been discharged.

505.10.6 Surface Preparation.

505.10.6 1 On new concrete decks, the surface shall be given a very rough texture while still plastic by use of a

wire comb or other approved texturing device which will produce a bondable surface acceptable to the engineer.

505.10.6 2 On existing concrete decks with existing wearing surfaces, the wearing surface shall be removed in

accordance with Sec 216. On existing concrete decks without existing wearing surfaces, the surface shall be scarified in accordance with Sec 216.

505.10.6 3 For non-hydro demolition projects, the textured or scarified deck shall be sand or shot blasted

followed by an air blast. The sand or shot blast shall remove all dirt, oil and other foreign material, as well as any unsound concrete or laitance from the surface and edges against which new concrete is to be placed. The compressor shall be equipped to prevent oil in the air supply. That portion of the curb and previously placed wearing surfaces against which new concrete is to be placed shall be sand or shot blasted. Any loose or foreign material detected on the concrete surface prior to placement of the wearing surface shall be removed by sand, shot or air blasting. Clean-up and disposal of blast material shall be in accordance with Sec 202.3.1.3. The concrete surface may require retexturing where penetration of foreign material is evident. No contamination of the retextured or scarified concrete surface will be permitted.

505.10.6 4 For hydro demolition projects, total surface hydro demolition shall be performed in accordance with

Sec 216 and the following additional surface preparation.

505.10.6 4.1 All areas of the deck, where further removal of concrete was performed with pneumatic hammering

after the hydro demolition, shall be thoroughly sand or shot blasted to remove any loose material and micro- cracking. Clean-up and disposal of blast material shall be in accordance with Sec 202.3.1.3.

505.10.6 4.2 After completion of sand or shot blasting and associated clean-up of debris, the entire deck surface

shall be thoroughly cleaned by a minimum 7000 psi pressure water blasting to remove all debris and slurry residue within 24 hours prior to wearing surface placement begins. Water blasting shall continue until the run- off water from cleaning flows clear.

505.10.6 4.3 After cleaning, the deck surface shall be thoroughly saturated to the point that the surface does not

dry out, and any excess water removed with compressed air. Clean polyethylene sheeting shall then be used to cover the deck completely until such time as the wearing surface is placed. Just prior to placement of the wearing surface, the deck shall be brought to a saturated surface dry (SSD) condition and maintained in a SSD condition throughout the pour, with no ponding of water.

505.10.6 4.4 Any standing water on the deck or in the depressed areas of monolithic deck repair shall be

removed prior to placement of wearing surface material

505.10.6 5 To assure that the thickness of the concrete wearing surface above the prepared surface will be as

specified on the plans, the clearance shall be checked in the following manner before concrete is placed. A filler block having a thickness 1/8 inch less than the wearing surface thickness shall be attached to the bottom of the screed. With screed guides in place, the screed shall be passed over the area to be concreted. Where the intended clearance does not allow use of this method, a stringline or other means shall be used, subject to approval from the engineer. All existing concrete shall be removed that does not have sufficient clearance.

505.10.7 Finishing Equipment.

505.10.7 1 The finishing machine shall be designed for striking off and finishing low slump concrete. The

machine shall be mechanically powered to operate forward and reverse in a smooth manner, under positive control of the operator. The basic machine shall be of a width to finish a basic 12-foot width of wearing surface and shall be adjustable for wider placements. The finishing machine shall be designed to allow the screeds to be extended with bolted units to match the extension of the basic unit. The drive wheels shall be of the type that may be replaced with solid rubber wheels to permit travel upon previously completed lanes of wearing surface when striking off the abutting lanes.

505.10.7 2 The finishing machine shall be equipped with two oscillating transverse screeds. The screeds shall

oscillate in a straight line. A swinging pendulum stoke shall not be used. The front screed shall vibrate uniformly for the full length of the screed. The vibrators shall be placed such that the screed vibrates efficiently and the frequency of the vibrators shall be controlled by the operator from the console to achieve the required density.

505.10.7 2.1 Screeds shall be held positive to the machine with rollers and, unless otherwise approved by the

engineer, shall be equipped with screed guides such as to control the profile grade of the finished wearing surface. The screed stroke shall be synchronized to speeds not exceeding 50 strokes per minute, with infinite variable control from the console. The screeds shall be capable of vertical lift when the machine is reversed for travel, and controlled for downward direction to the finishing position to permit feathering of the screeds to any previously finished surface.

505.10.7 2.2 The bottom face of the screeds shall be at least 5 inches wide, with an effective pressure to produce

no less than 75 psf. The bottom face of the screeds shall have a turned up leading edge to prevent tearing of the screeded surface and shall be adjustable for tilt and crown. The screed lengths shall be such to produce positive strike off and density of the concrete for at least 6 inches beyond the line where the saw cut for the longitudinal joint is to be made and to within one inch of the curb reinforcing steel or face of any curb barrier already in place.

505.10.7 3 The machine shall be equipped with a mechanically-powered adjustable auger positioned in front of

the lead screed. The strike-off shall travel back and forth for the full width to be screeded and shall be properly designed to meter the concrete to the screeds.

505.10.7 4 Heavy duty support rails shall be used to support the finishing machine. Support rails shall be

adjustable and the rail shall not deflect more than 1/32 inch between adjustable supports. Support rails shall be placed outside the area and parallel to axis of the area to be concreted. Support rails shall extend a sufficient distance beyond the end of the deck to allow the finishing machine to be completely removed from the deck surface such that hand finishing may proceed without interruption. The support rails shall be set to produce the final profile grade of the surface of the wearing surface. A hold-down device shot into the concrete will not be permitted unless the concrete is to be subsequently resurfaced. The proposed method of anchoring the support rails shall be submitted to the engineer for approval.

505.10.8 Placing and Finishing Concrete.

505.10.8 1 A lateral support for the concrete such as 2 by 4-inch lumber attached to the deck will be required at

least 6 inches beyond the line where the saw cut for the longitudinal joint is to be made.

505.10.8 2 In order to avoid locating the longitudinal construction joints in a wheelpath, the joints shall be

placed between the designated traffic lanes. The location of the longitudinal joints shall be subject to the approval from the engineer.

505.10.8 3 At transverse and longitudinal joints, the surface course previously placed shall be sawn to a straight

vertical edge before the adjacent course is placed.

505.10.8 4 Transverse joints in the wearing surface will be permitted if approved by the engineer. These joints

shall be located a minimum of 10 feet from the centerline of bent.

505.10.8 5 The contractor shall take every reasonable precaution to secure a smooth riding bridge deck. Prior to

placement operations, the contractor shall review with the engineer, equipment, procedures, personnel and previous results as well as inspection procedures to assure coordination. The contractor shall take every reasonable precaution to ensure that concrete can be produced and placed within the specified limits, continuously and with uniformity.

505.10.8 6 The areas of half-sole and full-depth repair shall have individual concrete placed in accordance with

Sec 704. These individual placements shall remain rough and shall be completed before the wearing surface course is started. Areas of half-sole, full-depth repair and all other patched areas shall be surface dried, sand or shot blasted and cleaned prior to the placement of low slump concrete wearing surface.

505.10.8 7 Prior to placement of low slump concrete, the cleaned surface shall be thoroughly wetted for a

minimum of three hours, then covered with polyethylene sheeting until the time of concrete placement. The surface shall be damp at the time the wearing surface is placed. Any standing water in depressions, holes or areas of concrete removal shall be blown out with compressed air. No free water or puddles of standing water shall exist at the time of placement.

505.10.8 8 The wheels of rubber wheeled vehicles or transport containers for the concrete shall not be permitted

to contact any portion of the existing concrete surface prior to placement of the concrete. Protection shall be provided for the concrete surface by means of plywood, mats or other suitable material placed on the surface. Any loose or foreign material or rubber marks accidentally deposited on the surface shall be removed by the contractor prior to low slump concrete placement.

505.10.8 9 Placement of the concrete shall be a continuous operation throughout the pour. Only the minimum

amount of concrete necessary for proper placement shall be placed in front of the screeds. If the concrete paver is stopped for any reason, all plastic concrete in front of the paver shall be covered with wet burlap. Concrete shall be placed and finished at a minimum of 2.5 cubic yards per hour for a 12-foot wide pour, except when the contractor elects to pour a wider section, the rate of pour shall be increased proportionately. When concrete is being mixed and placed at the specified minimum rate under normal operations, the finishing machine shall be designed such that the elapsed time between depositing the concrete on the deck and final screeding shall not exceed 10 minutes.

505.10.8 10 If concrete is added to the wearing surface behind the finishing machine, the area shall be

mechanically consolidated again by the finishing machine.

505.10.8 11 After finishing, the contractor shall check the surface with a lightweight 10-foot straightedge.

Causes for irregularities exceeding 1/8 inch shall be eliminated and corrections shall be made.

505.10.8 12 The roadway surface finish shall be in accordance with Sec 703.3.5.5. The texture shall not extend

into the areas within approximately 12 inches of curbs.

505.10.8 13 After texturing the concrete surface, but before applying the wet cure, all vertical joints with the

adjacent concrete shall be sealed by painting with thinned grout consisting of equal parts cement, sand and sufficient water for the mixture to be the consistency of paint.

505.10.8 14 After the joint painting is completed, the freshly placed lane and joint shall be promptly covered

with a single layer of clean, wet burlap. Care shall be exercised to ensure that the wet burlap is well drained and that the burlap is placed as soon as the surface will support the burlap without deformation.

505.10.8 15 The wet cure shall be applied within 30 minutes after the concrete has been placed on the deck,

except when the surface will be excessively marred by doing so, as determined by the engineer. If the concrete requires refinishing because of failure to meet density requirements, the time will be extended 15 minutes. Failure to apply wet cure within the required time will be cause for rejecting the work affected. Surface concrete in the rejected area shall be removed and replaced by the contractor at the contractor's expense.

505.10.8 16 The surface shall receive a wet cure of at least 72 hours.

505.10.8 17 After placement and cure of the low slump concrete, the finished deck will be tested to detect

unbonded areas.

505.10.8 18 As soon as curing has been completed, the riding surface will be thoroughly straightedged by the

engineer and all variations exceeding 1/8 inch in 10 feet will be plainly marked. Areas more than 1/8 inch high shall be removed by an approved device consisting of multiple cutting edges leaving a grooved surface finish comparable to that produced by the texturing device. A bush hammer or other impact device shall not be used.

505.10.8 19 The surface of low slump concrete shall be sealed in accordance with Sec 703.3.8 and payment for

furnishing and placing shall be included in the contract unit price for other items.

505.10.9 Supplementary Wearing Surface Material This work shall consist of providing and placing

additional wearing surface material in excess of the material required for the wearing surface at plan thickness.

505.10.9 1 Supplementary wearing surface material will be required when conditions require the actual wearing

surface thickness to exceed plan thickness, including but not limited to:

505.10.9 2 Supplementary wearing surface material will be required to fill the depressions of monolithic deck

repair in the deck below the bottom of the planned deck wearing surface thickness. This material is placed monolithic during the deck wearing surface process.

505.10.10 Limitations of Operations.

505.10.10 1 Vehicle traffic shall not be permitted on the low slump concrete surface for 72 hours and until 3,000

psi compressive strength is attained.

505.10.10 2 No low slump concrete shall be placed at ambient temperatures below 45 F or above 85 F. Concrete

placement may begin when the air temperature and deck temperature is 45 F and rising. Concrete shall not be exposed to freezing temperatures until a strength of 3,000 psi has been attained. Any concrete damaged by freezing shall be removed and replaced at the contractor's expense.

505.10.10 3 When the weather forecast predicts temperatures of 85 F or higher, the contractor shall schedule

placing and finishing low slump concrete during hours in which the ambient temperature will be lower than 85

505.10.10 4 Concrete shall not be placed adjacent to a parallel surface course that is less than 72 hours old. This

restriction will not apply to a continuation of placement in a lane or strip beyond a joint in the same lane or strip.

505.10.10 5 Preparation of the area may be started in a lane or strip adjacent to a newly placed surface the day

following placement of the new surface. If this work is started before the end of the 72-hour curing period, the work shall be restricted as follows:

505.10.11 Removal. All material removed shall be disposed of by the contractor at the contractor’s expense in a

location meeting the approval of the engineer.

505.10.12 Repair.

505.10.12 1 Unbonded areas will be marked by the engineer. The contractor shall saw cut and remove the

affected area. All saw cuts shall be straight vertical lines and form square corners at all changes in direction. After removal of the concrete, the surface of the area to be repaired and vertical saw cuts shall be cleaned of all loose or foreign material by sand or shot blasting and then air blasting. The surface shall be comparable to the original concrete surface prior to the original wearing surface being placed.

505.10.12 2 The concrete used for repair shall meet the same requirements as the original mixture. The concrete

shall be vibrated with a surface or pan-type vibrator to obtain compaction. Spud type vibrators shall not penetrate to contact with the original concrete. Surface finish and curing shall be in accordance with the specifications for the mixture used.

505.10.13 Method of Measurement.

505.10.13 1 Final measurement of the wearing surface at plan thickness will not be made except for authorized

changes during construction or where appreciable errors are found in the contract quantity. Where required, the area of wearing surface will be measured to the nearest square yard based on measurement longitudinally from end to end of bridge deck and transversely between roadway face of curbs, excluding the area of any expansion devices. The revision or correction will be computed and added to or deducted from the contract quantity.

505.10.13 2 Measurement of supplementary wearing surface material will be made to the nearest cubic yard by

deducting the theoretical volume of material necessary to construct the wearing surface at plan thickness from the total volume of deck wearing surface material placed on the deck surface. Deductions will be made for:

505.10.14 Basis of Payment.

505.10.14 1 The accepted quantities of the wearing surface at plan thickness, complete in place, will be paid for

at the contract unit price.

505.10.14 2 The accepted quantities of supplementary wearing surface material, complete in place, will be paid

for at the fixed contract unit price specified in Sec 109.16. SECTION 505.20 LATEX MODIFIED CONCRETE.

505.20.1 Description. This work shall consist of constructing a latex modified concrete wearing surface on a

prepared surface in accordance with this specification, as shown on the plans or as directed by the engineer.

505.20.2 Material. All material shall be in accordance with Division 1000, Material Details, and specifically as

follows: Item Section Type I or II Cement 1019 Latex Emulsion Admixture 1054 Polyethylene Sheeting 1058 Water 1070

505.20.2 1 Aggregate shall be in accordance with Sec 505.10.2.

505.20.2 2 Pozzolanic material or Portland pozzolan cements shall not be used.

505.20.2 3 Latex admixture shall be kept in a suitable enclosure that will protect the admixture from freezing

and from exposure to temperatures in excess of 85 F. Drums of latex admixture to be stored at the work site in direct sunlight shall be completely covered with a suitable insulating blanket material to maintain an enclosed temperature below 85 F.

505.20.3 Concrete Mixture.

505.20.3 1 The contractor shall submit a mix design to Construction and Materials meeting the following

requirements: Property Requirement Air Content, percent 0.0 to 6.5 Slump, inches, max. 9.0 Fine Aggregate, % of total aggregate by absolute volume50 to 55 Cement Content, lb/cy, min. 658 Latex Emulsion Admixture, gal/cy, min. 24.5 Net Water ª-Cement Ratio, lb water/lb cement, max. 0.40 a Net water shall be considered the quantity of mixing water added, plus the non-solid portion of the latex emulsion.

505.20.3 2 Any change in mix design or proportions shall be approved by the engineer.

505.20.3 3 Anti-foam additives, as recommended by the latex emulsion manufacturer, may be required if the

concrete mixture entrains air above the specified amount.

505.20.3 4 Air-entraining admixtures shall not be added.

505.20.4 Testing. Testing will be done in accordance with Sec 505.10.4, except the slump test will be conducted

4 to 5 minutes after discharge from the mixer. During the waiting period, concrete shall be deposited on the deck and shall not be disturbed.

505.20.5 Mixing.

505.20.5 1 The concrete shall be volumetrically mixed at the bridge site by a continuous mixer in accordance

with Sec 501. In addition to other requirements, the mixer shall provide positive control of the latex emulsion into the mixing chamber and the latex emulsion shall calibrate to within ± 2 percent of that required. The mixer shall be capable of continuously circulating the latex emulsion and shall have a flow-through screen between the storage tank and the discharge.

505.20.5 2 The concrete discharged from the mixer shall be uniform in composition and consistency. Mixing

capability shall be such that initial and final finishing operations can proceed at a steady pace. Final finishing shall be completed before the formation of a plastic surface film.

505.20.5 3 The moisture content of aggregate at the time of proportioning shall be such that water will not drain

or drip from a sample. Coarse and fine aggregate shall be furnished and handled to avoid variations in the moisture content affecting the uniform consistency of the concrete.

505.20.5 4 Each drum of latex admixture shall be mechanically agitated or hand rolled until thoroughly mixed

prior to being introduced into the mixer storage compartment. Latex admixture that is stored in the mixer storage compartment overnight or during delays in mixing of four hours or more shall be agitated by at least two complete cycles in a continuous circulating pump or by mechanical means in the storage compartment. The flow through screen shall be cleaned immediately prior to beginning proportioning and as often as necessary thereafter. Latex admixtures of different brands shall not be combined together in any manner.

505.20.6 Surface Preparation. Surface preparation shall be in accordance with Sec 505.10.6, except as

specified herein.

505.20.6 1 Prior to scarifying or chipping on concrete adjacent to latex modified concrete, 96 hours of curing

shall elapse. If practical, all scarifying by mechanical units shall be completed prior to placing any latex modified concrete, unless otherwise shown on the plans. Areas from which unsound concrete and patches have been removed shall be kept free of slurry produced by wet sawing or wet scarifying by planning the work such that this slurry will drain away from the completed areas of preparation.

505.20.6 2 On both existing and new decks for non-hydro demolition projects, within 24 hours prior to placing

latex modified concrete, the entire surface shall be thoroughly cleaned by sand or shot blasting followed by an air blast. Clean-up and disposal of blast material shall be in accordance with Sec 202.3.1.3.

505.20.7 Finishing Equipment.

505.20.7 1 The finishing machine shall be self-propelled and shall be capable of forward and reverse movement

under positive control, with a provision for raising all screeds to clear the screeded surface for traveling in reverse. A self-propelled finishing machine with one or more rollers, augers and 1500 to 2500 vpm vibratory pans shall be used. A drag float may be necessary. Any modifications will be subject to approval from the engineer.

505.20.7 2 Support rails shall be in accordance with Sec 505.10.7.4.

505.20.8 Placing and Finishing Concrete. Placing and finishing shall be in accordance with Sec 505.10.8

except as specified herein.

505.20.8 1 Prior to placement of latex modified concrete, the cleaned surface shall be thoroughly wetted for a

minimum of three hours, then covered with polyethylene sheeting until time of concrete placement. The surface shall be damp at the time the wearing surface is placed. Any standing water in depressions, holes or areas of concrete removal shall be blown out with compressed air. No free water or puddles of standing water shall exist at the time of placement.

505.20.8 2 Hand vibrators shall be used in areas of monolithic deck repair in the deck below the bottom of the

planned deck wearing surface thickness where concrete is being placed around reinforcement, deeper areas within the pour, and along curb lines and construction joints. Deep areas shall be filled in advance during the wearing surface pour so the material stiffens enough that it will not roll back under the paving screed.

505.20.8 3 Expansion joints and dams shall be formed in the concrete wearing surface. Formation of the joint by

sawing through the wearing surface will not be permitted.

505.20.8 4 Texturing shall occur immediately after finishing and before the plastic film forms on the surface.

Texturing shall be performed in a manner to prevent pulling the concrete away from an existing vertical face. Care shall be taken not to texture too deep and not to tear the surface.

505.20.8 5 Screed rails and headers shall be separated from the newly placed material by passing a pointing

trowel along the inside face. Metal expansion dams shall not be separated from the wearing surface. The trowel cut shall be made for the entire depth and length of rails or headers after the mixture has stiffened sufficiently and shall prevent the concrete from flowing back into the cut.

505.20.8 6 During placement of the wearing surface, all joints with adjacent concrete shall be sealed with a

mortar paste of equal parts cement and fine aggregate, using latex emulsion in lieu of mixing water.

505.20.8 7 The wet cure shall be applied promptly after the concrete has been placed on the deck without

deforming the finished surface.

505.20.8 8 The surface shall receive a wet cure for at least 48 hours.

505.20.8 9 After placement and cure of the latex modified concrete, the finished deck will be tested to detect

unbonded areas.

505.20.8 10 No surface sealing shall be applied to the latex modified concrete wearing surface.

505.20.9 Supplementary Wearing Surface Material. Supplementary wearing surface material shall be in

accordance with Sec 505.10.9.

505.20.10 Limitations of Operations.

505.20.10 1 No latex modified concrete shall be placed when the ambient or deck surface temperature is above

85 F. Deck temperature shall be determined in accordance with MoDOT Test Method TM 20.

505.20.10 2 No latex modified concrete shall be placed at ambient or deck surface temperatures below 45 F.

Latex modified concrete shall be protected to maintain a minimum specified curing temperature of 45 F. Any concrete damaged by freezing or that is exposed to a temperature of less than 45 during the first 8 hours after placement shall be removed and replaced at the contractor's expense.

505.20.10 3 The temperature of the latex modified concrete at time of placement shall be between 45 F and 90

505.20.10 4 No vehicular traffic shall be permitted on the latex modified concrete surface until the concrete is at

least 72 hours old and has attained a minimum compressive strength of 3,000 psi.

505.20.10 5 Concrete shall not be placed adjacent to a parallel surface course that is less than 96 hours old;

however, this restriction will not apply to a continuation of placement in a lane or strip beyond a joint in the same lane or strip.

505.20.10 6 Preparation of the area, except scarifying, may be started in a lane or strip adjacent to a newly

placed surface the day following the surface placement. If this work is started before the end of the 48-hour wet curing period, the work will be restricted such that any interference with the curing process is held to the minimum practical time.

505.20.10 7 Longitudinal construction joints shall be placed between designated traffic lanes. The location of

the longitudinal joints will be subject to the approval from the engineer.

505.20.10 8 Transverse joints in the wearing surface may be permitted if approved by the engineer. These joints

shall be located a minimum of 10 feet from the centerline of bent.

505.20.10 9 A header shall be installed in case of delay in the placement operations exceeding one-half hour in

duration. During minor delays of one-half hour or less, the end of the placement shall be protected from drying with several layers of wet burlap.

505.20.10 10 Adequate precautions shall be taken to protect freshly placed concrete from rain. All placing

operations shall cease when rain begins. The engineer may order removal of any material damaged by rainfall and such material shall be replaced in accordance with these specifications at the contractor's expense.

505.20.11 Removal. Removal shall be in accordance with Sec 505.10.11.

505.20.12 Repair. Repair shall be in accordance with Sec 505.10.12.

505.20.13 Method of Measurement. Measurement will be in accordance with Sec 505.10.13.

505.20.14 Basis of Payment. Payment will be in accordance with Sec 505.10.14.

SECTION 505.30 SILICA FUME CONCRETE.

505.30.1 Description. This work shall consist of constructing a silica fume concrete wearing surface on a

prepared surface in accordance with this specification, as shown on the plans or as directed by the engineer.

505.30.2 Material. All material shall be in accordance with Division 1000, Material Details, and specifically as

follows: Item Section Type I Cement 1019 Air Entraining Admixture 1054 Retarding Admixture 1054 Water-Reducing Admixture 1054 Burlap 1055 Polyethylene Sheeting 1058 Water 1070

505.30.2 1 Silica fume shall be in accordance with Sec 501.

505.30.2 2 Aggregate shall be in accordance with Sec 505.10.2.

505.30.2 3 Pozzolanic material, other than silica fume or Portland pozzolan cements shall not be used.

505.30.2 4 A retarding admixture may be permitted, if recommended by the manufacturer of the silica fume

admixture.

505.30.2 5 Approved Type F or G high range water-reducing admixtures will be permitted if specified or

recommended by the supplier of the silica fume admixture.

505.30.3 Concrete Mixture.

505.30.3 1 The contractor shall submit a mix design to Construction and Materials with the following

properties: Property Requirement Air Content, percent, min. 5.0 Slump, inches 3.0 to 7.5 Cement Content, lb/cy, min 640 Water/Cement Ratio, lb water/lb cement, max. 0.37 Silica Fume, % replacement of cement 6.0 to 8.0 Fine Aggregate, % of total aggregate by absolute volume 50 to 55 High Range Water Reducer As required

505.30.3 2 The water content shall include all free moisture in the fine and coarse aggregate, water content of

the silica fume admixture and water content of the high range water reducer.

505.30.3 3 The contractor shall designate in the mix design letter what target the slump will be in the field.

505.30.4 Testing. Testing will be done in accordance with Sec 505.10.4.

505.30.5 Mixing.

505.30.5 1 Silica fume concrete shall be batched and mixed in accordance with Sec 501, except as herein

specified.

505.30.5 2 High range water-reducing admixtures shall be incorporated and mixed into the silica fume concrete

in accordance with the silica fume admixture manufacturer's recommendations and as approved by the engineer. Water-reducing admixtures may be added by hand methods. The water-reducing admixture shall not be mixed with the air-entraining admixture nor shall the water reducer be added to the same portion of the mixing water as the air-entraining admixture. Either the air-entraining admixture or the water-reducing admixture shall be mixed into the concrete before the other is added.

505.30.5 3 Truck mixed silica fume concrete shall be initially mixed for at least 70 revolutions at a rate of no

less than 12 revolutions per minute or more than 18 revolutions per minute. Truck mixed silica fume concrete shall be transported to the work site at agitating speeds of 2 to 6 revolutions per minute. After arriving at the work site and before use, the silica fume concrete shall be mixed for at least 30 revolutions at 12 to 18 revolutions per minute.

505.30.5 4 If on-site rotating paddle-type mixers or on-site rotating drum mixers are used, the length of mixing

time and the revolution rate shall be as recommended by the silica fume admixture manufacturer.

505.30.5 5 The silica fume admixture manufacturer's technical representative shall advise the engineer in

writing of the proper batching sequence, mixing time, mixing speed and other handling procedures necessary to produce a uniform, homogeneous mixture in accordance with this specification prior to preparation of silica fume concrete trial batches or placement of any silica fume concrete.

505.30.5 6 Prior to placement of concrete, the contractor may be required to prepare trial batches of concrete for

tests. Trial batches shall comply with and be paid for in accordance with Sec 501.

505.30.6 Surface Preparation. Surface preparation shall be in accordance with Sec 505.10.6.

505.30.7 Finishing Equipment. The finishing machine shall be designed for striking off and finishing silica

fume concrete wearing surface. The finishing machine, screeds, traveling strike off and support rails shall be in accordance with Sec 505.10.7.

505.30.8 Placing and Finishing Concrete. Placing and finishing shall be in accordance with Sec 505.10.8, except

as specified herein.

505.30.8 1 The cleaned areas to receive the wearing surface shall be thoroughly and continuously wetted with

water at least three hours before placement of the wearing surface is started, then covered with polyethylene sheeting until the time of placement. Any accumulations of water shall be dispersed or removed prior to applying the wearing surface.

505.30.8 2 Hand vibrators shall be used in areas of monolithic deck repair in the deck below the bottom of the

planned deck wearing surface thickness where concrete is being placed around reinforcement, deeper areas within the pour, and along curb lines and construction joints. Deep areas shall be filled in advance during the wearing surface pour so the material stiffens enough that it will not roll back under the paving screed.

505.30.8 3 Since silica fume concrete produces very little bleed water, the engineer may require one or both of

the following procedures to maintain a surface film until the burlap is placed.

505.30.8 3.1 A commercially available evaporative retarder may be used judiciously with a misting device

during the finishing process until the wet burlap is applied only to prevent the surface of the concrete from drying out. The evaporative retarder shall not be used to increase surface workability.

505.30.8 3.2 Fogging may be done to increase humidity in the area of placement. Any fogging shall be done

with nozzles specifically designed for fogging, with a maximum rate of one gallon per minute per nozzle.

505.30.8 4 The surface shall receive a wet cure for at least 7 days. Time when the ambient temperature is below

45 F will not be counted as cure time. Cure shall be continued until 3,000 psi compressive strength has been attained.

505.30.8 5 The finished deck will be examined for cracking. If cracking is found, the engineer will determine

whether cracking is detrimental, whether remedial surface repairs are needed or whether the wearing surface in the cracked area should be removed and replaced. All remedial surface repairs, removal or replacement shall be done by the contractor at the contractor's expense.

505.30.8 6 After placement and cure of the silica fume concrete, the finished deck will be tested to detect

unbonded areas.

505.30.8 7 No surface sealing shall be applied to the silica fume concrete wearing surface.

505.30.9 Supplementary Wearing Surface Material. Supplementary wearing surface material shall be in

accordance with Sec 505.10.9.

505.30.10 Limitations of Operations. Operations shall be limited in accordance with Sec 505.10.10, except as

specified herein.

505.30.10 1 Vehicular traffic shall not be permitted on the silica fume concrete surface for seven days, and in no

case until 3000 psi compressive strength is attained.

505.30.10 2 Silica fume concrete shall not be placed when the air temperature or deck temperature is below 45 F

or above 85 F. Concrete placement may begin when the air temperature and deck temperature are 45 F and rising. Concrete shall not be exposed to freezing temperatures until a strength of 3000 psi has been attained. Any concrete damaged by freezing shall be removed and replaced at the contractor's expense.

505.30.10 3 When the weather forecast predicts temperatures of 85 F or higher, the contractor shall schedule

placing and finishing silica fume concrete during hours in which the ambient temperature will be lower than 85

505.30.10 4 Since silica fume concrete may not exhibit bleed water, the probability of plastic shrinkage cracking

is increased. At surface evaporation rates above 0.1 pound per square foot per hour, plastic shrinkage cracking is probable and the contractor shall take precautions such as erecting windbreaks, lowering the mix temperature or delaying operations until ambient temperatures are lower. Fogging the concrete surface will only be permitted as provided for in this specification. Surface evaporation rates may be predicted from mix temperature, air temperature, relative humidity and wind velocity, using Figure 1 of the 1986 revised edition of ACI 308-81, Standard Practice for Curing Concrete.

505.30.11 Removal. Removal shall be in accordance with Sec 505.10.11.

505.30.12 Repair. Repairs shall be in accordance with Sec 505.10.12.

505.30.13 Method of Measurement. Measurement will be in accordance with Sec 505.10.13.

505.30.14 Basis of Payment. Payment will be in accordance with Sec 505.10.14.

SECTION 505.40 LATEX MODIFIED VERY EARLY STRENGTH CONCRETE.

505.40.1 Description. This work shall consist of constructing a latex modified very early strength concrete

wearing surface on a prepared surface in accordance with this specification, as shown on the plans or as directed by the engineer.

505.40.2 Material. All material shall be in accordance with Sec 505.10.2, Division 1000, Materials Details and

specifically as follows: Item Section Latex Emulsion Admixture 1054 Polyethylene Sheeting 1058 Water 1070

505.40.2 1 Hydraulic cement shall be in accordance with ASTM C 1600, Type VRH. Type HE (ASTM C 1157)

or Type III cement will not be permitted.

505.40.2 2 Coarse aggregate shall be an approved crushed limestone, crushed quartzite, flint chat from the

Joplin area, or porphyry in accordance with Sec 1005, Gradation E or Gradation F, except the percentage of deleterious substances shall not exceed the following values, and the sum of percentages of all deleterious substances shall not exceed one percent. Item Percent by Weight Deleterious Rock 1.0 Shale and Pyrite 0.2 Chert in Limestone 0.5 Other Foreign Material 0.1

505.40.2 3 Fine aggregate shall be in accordance with Sec 1005 and shall be Class A sand in accordance with

Sec 501.

505.40.2 4 With approval of the engineer, other gradations of coarse or fine aggregate may be used, however all

quality requirements, including a maximum of 2 percent passing the No. 200 for fine and coarse aggregate, shall apply and the maximum aggregate size shall not exceed that of Sec 1005, Grade E aggregate.

505.40.2 5 Pozzoloanic material or Portland pozzolan cements shall not be used.

505.40.2 6 Latex admixture shall be kept in suitable enclosures which will protect it from freezing and from

exposure to temperatures in excess of 85 F.

505.40.3 Concrete Mixture.

505.40.3 1 The concrete mixture shall meet the following requirements:

Property Specific Value Air Content percent 0.0 to 6.5 Slump, inches, max. 9.0 Fine Aggregate, % of total aggregate by weight 50 to 55 Cement Content, lb/cy, min. 658 Latex Emulsion Admixture, gal/cy, min. 24.5 Net Water ª-Cement Ratio, lb water/lb cement, max. 0.42 aNet water shall be considered the quantity of mixing water added plus the non-solid portion of the latex emulsion.

505.40.3 2 Chloride permeability shall not be greater than 1000 coulombs when tested in accordance with

AASHTO T 277. Tests shall be performed on specimens at 28-days. This test shall be performed on each mixture submitted for approval. The tests are to be performed by a qualified commercial laboratory.

505.40.3 3 The mixture shall be designed to develop a minimum 28-day compressive strength of 4,500 psi.

505.40.3 4 Anti-foam additives as recommended by the latex emulsion manufacturer may be required if the

concrete mixture entrained air is above the specified amount.

505.40.3 5 Air-entraining admixtures shall not be added.

505.40.3 6 A set control in accordance with the cement manufacturer’s recommendation may be considered.

505.40.3 7 Admixtures containing calcium chloride shall not be used.

505.40.3 8 Mix Design. The contractor shall submit the mix design to Construction and Materials for approval.

The mix design shall be within the limits specified in this specification. The mix design shall also include actual test results for the following information:

505.40.3 8.1 If other aggregate gradations than standard specifications are utilized, the contractor shall designate

the intended target gradation and allowable gradation range for each fraction. The target gradations and allowable gradation ranges will be used for inspection and quality control of the aggregates.

505.40.3 8.2 Any change in mix design or proportions shall be approved by the engineer.

505.40.4 Testing. Testing will be done in accordance with Sec 505.10.4, except that the slump test will be

conducted 4 to 5 minutes after discharge from the mixer. During the waiting period, concrete shall be deposited on the deck and shall not be disturbed.

505.40.5 Mixing.

505.40.5 1 The concrete shall be volumetrically mixed at the bridge site by a continuous mixer in accordance

with Sec 501. In addition to other requirements, the mixer shall provide positive control of the latex emulsion into the mixing chamber, and the latex emulsion shall calibrate to within ±2 percent of that required. The mixer shall be capable of continuously circulating the latex emulsion and have a flow-through screen between the storage tank and the discharge.

505.40.5 2 The concrete discharged from the mixer shall be uniform in composition and consistency. Mixing

capability shall be such that initial and final finishing operations can proceed at a steady pace. Final finishing shall be completed before the formation of a plastic surface film on the surface.

505.40.5 3 The moisture content of aggregates at the time of proportioning shall be such that water will not

drain or drip from a sample. Coarse and fine aggregate shall be furnished and handled to avoid variations in the moisture content affecting the uniform consistency of the concrete.

505.40.5 4 Each drum of latex admixture shall be mechanically agitated or hand rolled until thoroughly mixed

prior to being introduced into the mixer storage compartment. Latex admixture that is stored in the mixer storage compartment overnight or during delays in mixing of four hours or more shall be agitated by at least two complete cycles in a continuous circulating pump or by mechanical means in the storage compartment. The flow through screen shall be cleaned immediately prior to beginning proportioning and as often as necessary thereafter. Latex admixtures of different brands shall not be combined together in any manner.

505.40.5 5 The water/cement ratio shall be within 0.02 of that specified in the approved mix design. If

adjustments for water content beyond that are necessary, a previously tested and approved mixture shall be used.

505.40.5 6 Prior to placement of concrete, the contractor shall be required to prepare trial batches of concrete for

testing. Trial batches shall comply with the limits specified in this specification.

505.40.6 Surface Preparation. Surface preparation shall be in accordance with Sec 505.10.6 except as

specified herein.

505.40.6 1 Prior to scarifying or chipping on concrete adjacent to latex modified very early strength concrete, 24

hours of curing shall elapse. If practical, or unless otherwise shown on the plans, all scarifying by mechanical units shall be completed prior to placing any latex modified very early strength concrete. Areas from which unsound concrete and patches have been removed shall be kept free of slurry produced by wet sawing or wet scarifying by planning the work such that this slurry will drain away from the completed areas of preparation.

505.40.6 2 On both existing and new decks for non-hydro demolition projects, within 24 hours before placement

of the wearing surface begins, the entire surface shall be thoroughly cleaned by water blasting followed by an air blast in accordance with Sec 505.10.6.4.2..

505.40.6 3 Clean-up and disposal of blast material shall be in accordance with Sec 202.3.1.3..

505.40.7 Finishing Equipment.

505.40.7 1 The finishing machine shall be in accordance with Sec 505.20.7.

505.40.7 2 Support rails shall be in accordance with Sec 505.10.7..

505.40.8 Placing and Finishing Concrete. Placing and finishing shall be in accordance with Sec 505.10.8,

except as specified herein.

505.40.8 1 Prior to placement of latex modified very early strength concrete, the cleaned surface shall be

thoroughly wetted for a minimum of one hour, then covered with polyethylene sheeting until time of concrete placement. The surface shall be damp at the time the wearing surface is placed. Any standing water in depressions, holes or areas of concrete removal shall be blown out with compressed air. No free water or puddles of standing water shall exist at the time of placement.

505.40.8 2 Hand vibrators shall be used in areas of monolithic deck repair in the deck below the bottom of the

planned deck wearing surface thickness where concrete is being placed around reinforcement, deeper areas within the pour, and along curb lines and construction joints. Deep areas shall be filled in advance during the wearing surface pour so the material stiffens enough that it will not roll back under the paving screed.

505.40.8 3 Expansion joints and dams shall be formed in the concrete wearing surface. Formation of the joint by

sawing through the wearing surface will not be allowed.

505.40.8 4 Water shall not be added to the surface of the concrete during finishing. A commercially available

evaporation retardant may be used judiciously with a misting device during the finishing process until the wet burlap is applied only to prevent the surface of the concrete from drying out. The evaporation retardant shall not be used to increase surface workability.

505.40.8 5 Texturing shall occur immediately after finishing and before the plastic film forms on the surface.

Texturing shall be performed in a manner to prevent pulling the concrete away from an existing vertical face. Care shall be taken not to texture too deep and not to tear the surface.

505.40.8 6 Screed rails and headers shall be separated from the newly placed material by passing a pointing

trowel along their inside face. Metal expansion dams shall not be separated from the new wearing surface. The trowel cut shall be made for the entire depth and length of rails or headers after the mixture has stiffened sufficiently and shall prevent the concrete from flowing back into the cut.

505.40.8 7 During placement of the wearing surface, all joints with adjacent concrete shall be sealed with a

mortar paste of equal parts cement and fine aggregate, using latex emulsion in lieu of mixing water.

505.40.8 8 The wearing surface concrete shall be moist cured from the time placed until opened to traffic.

505.40.8 9 The wet cure shall be applied promptly after the concrete has been placed on the deck without

deforming the finished surface.

505.40.8 10 Within one hour of covering with wet burlap, a layer of white polyethylene sheeting shall be placed

on the wet burlap. The surface shall receive a wet cure until the latex modified very early strength concrete has attained a compressive strength of at least 3000 psi.

505.40.8 11 The thickness of the wearing surface shall not exceed 3 inches, unless otherwise approved by the

engineer.

505.40.8 12 The finished deck will be examined for cracking. If cracking is found, the engineer will determine

whether cracking is detrimental, whether remedial surface repairs are needed or whether the wearing surface in the cracked area should be removed and replaced. All remedial surface repairs, removal or replacement shall be done by the contractor at the contractor’s expense.

505.40.8 13 After placement and curing of the latex modified very early strength concrete, the finished deck will

be tested to detect unbonded areas.

505.40.8 14 No surface sealing shall be applied to the latex modified very early strength concrete wearing

surface.

505.40.9 Supplementary wearing surface material shall be in accordance with Sec 505.10.9.

505.40.10 Limitations of Operations.

505.40.10 1 No latex modified very early strength concrete shall be placed when the ambient or deck surface

temperature is above 85 F. Deck temperature shall be determined in accordance with MoDOT Test Method T20.

505.40.10 2 Since latex modified very early strength concrete may not exhibit bleed water, the probability of

plastic shrinkage cracking is increased. At surface evaporation rates above 0.1 pounds per square foot per hour plastic shrinkage cracking is probable and the contractor should take precautions such as erecting windbreaks, lowering the mix temperature or delaying operations until ambient temperatures are lower. Fogging the concrete surface will only be allowed, as provided for in this specification. Surface evaporation rates can be predicted from mix temperature, air temperature, relative humidity and wind velocity using Figure 1 of ACI 308-81 (revised 1986) "Standard Practice for Curing Concrete".

505.40.10 3 A fogging system shall be in-place prior to concrete placement. The fogging system shall consist of

pressurized equipment that distributes water at minimum rate of 0.10 gallon per hour per square foot. The fogging system shall apply the fog uniformly over the entire surface of the bridge deck. The fogging system shall produce atomized water that has a droplet with a maximum diameter of 0.003 inch and which keeps the finished deck surface saturated without producing standing water. The contractor shall submit a letter certifying that their fogging system is in accordance with this specification.

505.40.10 4 The fogging system shall be started progressively along the length of the deck, during or

immediately after floating.

505.40.10 5 No latex modified very early strength concrete shall be placed at ambient or deck surface

temperatures below 45 F. Latex modified very early strength concrete shall be protected to maintain a minimum specified curing temperature of 45 F. The contractor shall provide a method, meeting the approval of the engineer, of monitoring the concrete that demonstrates that the concrete has been maintained above the minimum curing temperature and has been protected from freezing. Any concrete damaged by freezing or which is exposed to a temperature of less than 45 F during the first 8 hours after placement shall be removed and replaced at the contractor's expense.

505.40.10 6 The temperature of the latex modified very early strength concrete at time of placement shall be

between 45 F and 90 F. If either the aggregate or water is heated, the maximum temperature for each shall be 100 F at the time of addition to the mix. Any method of heating during the mixing of concrete may be used provided the heating apparatus will heat the mass uniformly and avoid hot spots which will burn the material. Cement or aggregate containing lumps or crusts of hardened material or frost shall not be used.

505.40.10 7 No vehicle traffic shall be permitted on the latex modified very early strength concrete surface until

the latex modified very early strength concrete has attained a minimum compressive strength of 3200 psi. Compressive strength will be determined by tests conducted in accordance with MoDOT test methods.

505.40.10 8 Concrete shall not be placed adjacent to a parallel surface course which is less than 24 hours old;

however, this restriction will not apply to a continuation of placement in a lane or strip beyond a joint in the same lane or strip.

505.40.10 9 Preparation of the area, except scarifying, may be started in a lane or strip adjacent to newly placed

surface the day following the surface placement. If this work is started before the end of the curing period, the work will be restricted such that any interference with the curing process is held to the minimum practical time only.

505.40.10 10 Longitudinal construction joints shall be placed between designated traffic lanes. The location of

the longitudinal joints shall be subject to the approval from the engineer.

505.40.10 11 Transverse joints in the wearing surface may be permitted if approval by the engineer. Transverse

joints shall be located a minimum of 10 feet from the centerline of bent.

505.40.10 12 A header shall be installed in case of delay in the placement operations exceeding one-half hour in

duration. During minor delays of one-half hour or less, the end of the placement shall be protected from drying with several layers of wet burlap.

505.40.10 13 Adequate precautions shall be taken to protect freshly placed concrete from rain. All placing

operations shall stop when rain begins. The engineer may order removal of any material damaged by rainfall and such material shall be replaced in accordance with this specification at the contractor's expense.

505.40.11 Removal. Removal shall be in accordance with Sec 505.10.11.

505.40.12 Repair. Repair shall be in accordance with Sec 505.10.12.

505.40.13 Method of Measurement. Measurement will be in accordance with Sec 505.10.13.

505.40.14 Basis of Payment. Payment will be in accordance with Sec 505.10.14.

SECTION 505.50 CSA CEMENT VERY EARLY STRENGTH CONCRETE.

505.50.1 Description This work shall consist of constructing a calcium sulfoaluminate dicalcium silicate (CSA)

cement very early strength concrete wearing surface on a prepared surface in accordance with this specification, as shown on the plans or as directed by the engineer.

505.50.2 Material All material shall be in accordance with Division 1000, Materials Details and specifically as

follows: Item Section Water Reducing Admixture 1054 Burlap 1055 Polyethylene Sheeting 1058 Water 1070

505.50.2 1 CSA cement shall be a Type VRH (very rapid hardening) in accordance with ASTM C 1600. Mixing

other hydraulic cements with CSA cement will not be permitted.

505.50.2 2 Coarse aggregate shall be an approved crushed limestone, crushed quartzite, flint chat from the

Joplin area, or porphyry in accordance with Sec 1005, Gradation E, except the percentage of deleterious substances shall not exceed the following values, and the sum of percentages of all the deleterious substances shall not exceed one percent. Item Percent by Weight Deleterious Rock 1.0 Shale and Pyrite 0.2 Chert in Limestone 0.5 Other Foreign Material 0.1

505.50.2 3 Fine aggregate shall be in accordance with Sec 1005 and shall be Class A sand in accordance with

Sec 501.

505.50.2 4 With approval of the engineer, other gradations of coarse or fine aggregate may be used, however all

quality requirements, including a maximum of 2 percent passing the No. 200 for fine and coarse aggregate, shall apply and the maximum aggregate size shall not exceed that of Sec 1005, Grade E aggregate.

505.50.2 5 Pozzoloanic material or Portland pozzolan cements shall not be used.

505.50.2 6 Type S admixtures in accordance with ASTM C 494 may be used, if approved by the engineer.

505.50.3 Concrete Mixture.

505.50.3 1 The concrete mixture shall meet the following requirements:

Property Requirement Air Content, percent 0.0 to 6.5 Water-Cement Ratio, lb water/lb cement 0.42 to 0.45 Slump (at discharge), inches 7.0 to 9.0 Slump (after discharge)ª, inches 3.0 to 6.0 Fine Aggregate, % of total aggregate by weight 50 to 55 Cement Content, lb/cy, min. 575 ª Conduct test 7 to 10 minutes after discharge

505.50.3 2 Chloride permeability shall not be greater than 1000 coulombs when tested in accordance with

AASHTO T 277. Tests shall be performed on specimens at 28 days. This test shall be performed on each mixture submitted for approval. Tests shall be performed by a qualified commercial laboratory.

505.50.3 3 The mixture shall be designed to develop a minimum 3-hour compressive strength of 3000 psi and a

minimum 28-day compressive strength of 4500 psi.

505.50.3 4 Air-entraining admixtures shall not be added.

505.50.3 5 A set control (citric acid) in accordance with the cement manufacturer’s recommendations may be

used.

505.50.3 6 Admixtures containing calcium chloride shall not be used.

505.50.3 7 Mix Design The contractor shall submit the mix design to Construction and Materials for approval.

The mix design shall be within the limits specified in this specification. The mix design shall also include actual results for the following information:

505.50.3 7.1 If other aggregate gradations than standard specifications are utilized, the contractor shall designate

the intended target gradation and allowable gradation range for each fraction. The target gradations and allowable gradation ranges will be used for inspection and quality control of the aggregates.

505.50.3 7.2 Any change in mix design or proportions shall be approved by the engineer.

505.50.4 Testing. Testing will be done in accordance with Sec 505.10.4, except that the slump test will also be

conducted 7 to 10 minutes after discharge from mixer. During the waiting period, concrete shall be deposited on the deck to allow for continued operations. Required adjustments to water shall be made upon notice of results of slump test.

505.50.5 Mixing.

505.50.5 1 The concrete shall be volumetrically mixed at the bridge site by a continuous mixer in accordance

with Sec 501.

505.50.5 2 The concrete discharge from the mixer shall be uniform in composition and consistency. Mixing

capability shall be such that initial and final finishing operations can proceed at a steady pace. Final finishing shall be completed before the formation of a plastic surface film on the surface.

505.50.5 3 The moisture content of aggregates at the time of proportioning shall be such that water will not

drain or drip from a sample. Coarse and fine aggregate shall be furnished and handled to avoid variations in the moisture content affecting consistency of the concrete.

505.50.5 4 Adjustments to the water-cement ratio shall be in accordance with Sec 505.50.3.1. If adjustments for

water content beyond that are necessary, a previously tested and approved mixture shall be used.

505.50.5 5 Prior to placement of concrete, the contractor shall be required to prepare trial batches of concrete for

testing. Trial batches shall comply with the limits specified in this specification.

505.50.6 Surface Preparation. Surface preparation shall be in accordance with Sec 505.10.6, except as

specified herein.

505.50.6 1 Scarifying or chipping shall not be started until 6 hours of curing of adjacent parallel courses of the

new wearing surface. Saw cutting of or adjacent to parallel courses of the new wearing surface shall not be started until 3 hours of curing of new wearing surface. If practical, or unless otherwise shown on the plans, all scarifying by mechanical units shall be completed prior to placing any wearing surface. Areas from which unsound concrete and patches have been removed shall be kept free of slurry produced by wet sawing or wet scarifying by planning the work such that slurry will drain away from the completed areas of preparation.

505.50.6 2 On both existing and new decks for non-hydro demolition projects, within 24 hours before placement

of the wearing surface begins, the entire surface shall be thoroughly cleaned by water blasting followed by an air blast in accordance with Sec 505.10.6.4.2.

505.50.7 Equipment.

505.50.7 1 The finishing machine shall be in accordance with Sec 505.20.7, except the allowance for the use of

truss or roller type screeds for narrow and short placements are subject to the approval of the engineer.

505.50.7 2 Support rails shall be in accordance with Sec 505.10.7.

505.50.8 Placing and Finishing Concrete. Placing and finishing shall be in accordance with Sec 505.10.8,

except as specified herein.

505.50.8 1 Prior to placement of wearing surface, the cleaned surface shall be thoroughly wetted for a minimum

of one hour, then covered with polyethylene sheeting until time of placement. All surfaces that will be covered with the wearing surface shall be damp at time of placement. Any standing water in depressions, holes or areas of concrete removal shall be blown out with compressed air or other type blowers sufficient for removal or removed with the use of vacuums. No free water or puddles of standing water shall exist at time of placement.

505.50.8 2 Hand vibrators shall be used in areas of monolithic deck repair in the deck below the bottom of the

planned deck wearing surface thickness where concrete is being placed around reinforcement, deeper areas within the pour, and along curb lines and construction joints. Deep areas shall be filled in advance during the wearing surface pour so the material stiffens enough that it will not roll back under the paving screed.

505.50.8 3 Expansion joints and dams shall be formed in the wearing surface. Formation of the joint by sawing

through the wearing surface will not be allowed.

505.50.8 4 Water shall not be added to the surface of the wearing surface during finishing. A commercially

available evaporation retardant may be used judiciously with a misting device during the finishing process until the wet burlap is applied only to prevent the surface of the concrete from drying out. The evaporation retardant shall not be used to increase the surface workability.

505.50.8 5 Texturing shall occur immediately after finishing and before the plastic film forms on the surface.

Texturing shall be performed in a manner to prevent pulling the concrete away from an existing vertical surface. Care shall be taken not to texture too deep and not to tear the surface.

505.50.8 6 Screed rails and headers shall be separated from the newly placed material by passing a pointing

trowel along their inside face. Metal expansion dams shall not be separated from the new wearing surface. The trowel cut shall be made for the entire depth and length of the rails or headers after the mixture has stiffened sufficiently and shall prevent the concrete from flowing back into the cut.

505.50.8 7 During placement of the wearing surface, all joints with adjacent concrete shall be sealed with a

mortar paste of equal parts cement and fine aggregate, using the CSA cement and water.

505.50.8 8 The wearing surface shall be wet cured from the time of placement a minimum of 3 hours and until a

compressive strength of 3200 psi is achieved.

505.50.8 9 Wet burlap shall be applied promptly after the wearing surface has been placed on the deck without

deforming the finish surface.

505.50.8 10 Within one hour of covering with burlap, a layer of white polyethylene sheeting shall be placed on

the wet burlap. The wearing surface material shall be wet at all times during curing process and may require additional wetting by contractor.

505.50.8 11 The thickness of the wearing surface shall not exceed 3 inches, unless otherwise approved by the

engineer.

505.50.8 12 The finished deck will be examined for cracking. If cracking is found, the engineer will determine

whether cracking is detrimental, whether remedial surface repairs are needed or whether the wearing surface in the cracked areas should be removed and replaced. All remedial surface repairs, removal or replacement shall be done by the contractor at the contractor’s expense.

505.50.8 13 After placement and curing of the wearing surface, the finished deck shall be tested to detect

unbonded areas.

505.50.8 14 No surface sealing shall be applied to the wearing surface.

505.50.9 Supplementary Wearing Surface Material. Supplementary wearing surface material shall be in

accordance with Sec 505.10.9.

505.50.10 Limitations of Operations.

505.50.10 1 No wearing surface shall be placed when ambient or deck surface temperature is above 85 F. Deck

temperature shall be determined in accordance with MoDOT Test Method T20.

505.50.10 2 Since CSA cement very early strength concrete will not exhibit bleed water, the probability of

plastic shrinkage surface cracking is increased. At surface evaporation rates above 0.1 pounds per square foot per hour plastic shrinkage is probable and the contractor shall take precautions such as erecting windbreaks, lowering the mix temperature, fogging or delaying operations until ambient temperatures and/or wind conditions are more favorable. Fogging the plastic concrete surface will only be allowed, as provided in this specification. Surface evaporation rates can be predicted from mix temperature, ambient temperature, relative humidity and wind velocity using Figure 1 of ACI 308-81 (revised 1986) “Standard Practice for Curing Concrete”.

505.50.10 3 A fogging system shall be in-place prior to concrete placement. The fogging system shall consist of

pressurized equipment that distributes water at a minimum rate of 0.10 gallons per hours per square foot. The fogging system shall apply the fog uniformly over the entire surface of the bridge deck. The fogging system shall produce atomized water that is a droplet with a maximum diameter of 0.003 inch and which keeps the finish deck surface saturated without producing standing water. The fogging system shall be started progressively along the length of the deck, during or immediately after floating. The contractor shall submit a letter certifying their fogging system is in accordance with this specification.

505.50.10 4 No wearing surface shall be placed at ambient or deck temperatures below 45 F. Concrete shall be

protected to maintain a minimum specified curing temperature of 45 F. The contractor shall provide a method, meeting the approval of the engineer, of monitoring the concrete that demonstrates the concrete has been maintained above the minimum curing temperature and has been protected from freezing. Any concrete damaged by freezing or which is exposed to a temperature of less than 45 F during the first 8 hours after placement shall be removed at the contractor’s expense.

505.50.10 5 The temperature of the concrete at time of placement shall be between 45 F and 90 F. If either the

aggregate or water is heated, the maximum temperature for each shall be 100 F at time of addition to the mix. Any method of heating during the mixing of concrete may be used provided the heating apparatus will heat the mass uniformly and avoid hot spots which will burn the material. Cement or aggregate containing lumps or crusts of hardened material or frost shall not be used.

505.50.10 6 No vehicle traffic shall be permitted on the wearing surface until the concrete has attained a

minimum compressive strength of 3200 psi. Compressive strength will be determined by tests conducted in accordance with MoDOT test methods.

505.50.10 7 Concrete shall not be placed adjacent to a parallel course which is less than 24 hours old; however,

this restriction will not apply to a continuation of placement in the lane or strip beyond a joint in the same lane or strip.

505.50.10 8 Preparation of an area, except scarifying, may be started in the lane or strip adjacent to newly

placed surface after 3 hours of wet curing. If this work is started before the end of the curing period, the work will be restricted such that any interference with the curing process is held to the minimum practical time only.

505.50.10 9 Longitudinal construction joints shall be placed between designated traffic lanes. The location of

the longitudinal joints shall be subject to the approval of the engineer.

505.50.10 10 Transverse joints in the wearing surface may be permitted if approved by the engineer. Transverse

joints shall be located a minimum of 10 feet from the centerline of bent.

505.50.10 11 A header shall be installed in case of delay in the placement operations exceeding one-half hour in

duration. During minor delays of one-half hour or less, the end of the placement shall be protected from drying with several layers of wet burlap.

505.50.10 12 Adequate precautions shall be taken to protect the placement from rain. All placing operations

shall stop when rain begins. The engineer may order removal of any material damaged by rainfall and such material shall be replaced in accordance with this specification at the contractor’s expense.

505.50.11 Removal. Removal shall be in accordance with Sec 505.10.11.

505.50.12 Repair. Repair shall be in accordance with Sec 505.10.12.

505.50.13 Method of Measurement. Measurement will be in accordance with Sec 505.10.13.

505.50.14 Basis of Payment. The basis of payment will be in accordance with Sec 505.10.14.

SECTION 505.60 STEEL FIBER REINFORCED CONCRETE.

505.60.1 Description. This work shall consist of constructing a steel fiber reinforced concrete wearing surface

on a prepared surface in accordance with this specification, as shown on the plans or as directed by the engineer.

505.60.2 Material.

505.60.2 1 Concrete shall be Class B-1 or B-2 as specified on the plans and in accordance with Sec 501.

505.60.2 2 Aggregate shall be in accordance with Sec 505.10.2.

505.60.2 3 Steel fibers shall be made from stainless steel and nominally be 2 inches long and meet the physical

property requirements prescribed in ASTM A820. One-inch Helix fibers are also allowed. Steel fibers shall have a quantity of at least 2000 fibers per pound and a fiber aspect ratio of 40 to 60. The steel fibers shall not have any hooks or 90-degree bends. The steel fibers shall be free from rust, oil and other deleterious materials. Steel fibers shall be transported, stored and applied to the concrete mixture in accordance with the manufacturer’s recommendations.

505.60.2 3.1 The contractor shall provide initial on-site technical assistance from the supplier of the steel fiber

reinforcement. Further technical assistance shall be available at the request of the engineer.

505.60.3 Concrete Mixture. The contractor shall prepare and submit the mix design and mixing procedures to

Construction and Materials for approval. The contractor shall not begin ordering materials until the mix design and mixing procedures are approved.

505.60.3 1 The contractor shall designate in the mix design letter what target the slump will be in the field.

505.60.3 2 The steel fiber dosage rate shall be 80 pounds per cubic yard of concrete.

505.60.3 3 Any change in mix design or proportions shall be approved by the engineer.

505.60.4 Testing. Testing shall be in accordance with Sec 505.10.4.

505.60.5 Mixing. Mixing shall be in accordance with Sec 501.

505.60.6 Surface Preparation. Surface preparation shall be in accordance with Sec 505.10.6.

505.60.7 Finishing Equipment. The finishing machine shall be designed for striking off and finishing steel

fiber reinforced concrete wearing surface. The finishing machine, screeds, traveling strike off and support rails shall be in accordance with Sec 505.10.7.

505.60.8 Placing and Finishing Concrete. Placing and finishing shall be in accordance with Sec 505.10.8,

except as specified herein.

505.60.8 1 Pumping shall generally be in accordance with Sec 703. Unless otherwise approved by the engineer,

the following practices shall be observed:

505.60.8 2 Placement Plan. At least six weeks prior to the first placement of the steel fiber reinforced concrete

wearing surface on the project, a pre-placement conference shall be held with the contractor, the steel fiber supplier, the engineer and other parties involved with the steel fiber reinforced concrete wearing surface on the project. The contractor shall present the plan for furnishing, placing, sampling and testing of the steel fiber reinforced concrete wearing surface in accordance with the requirements of this specification.

505.60.8 2.1 As part of the pre-placement conference a trial placement of steel fiber reinforced concrete wearing

surface shall be made. The trial placement shall use the same delivery and placing equipment as shall be used in the actual work and shall use the mix design as approved by the engineer. For pumped concrete, simulate as closely as possible the distance and height that the concrete is to be pumped. As a minimum, the trial placement shall be a 10-foot by 10-foot by 4-inch thick slab.

505.60.8 2.2 Placement of steel fiber reinforced concrete wearing surface for the project shall not be allowed

until the engineer approves the contractor’s plan, including the results of the trial placements. Mixing, pumping, placing and finishing techniques should ensure uniform fiber distribution throughout the mixture without fiber balling or segregation. After approval, the placement plan shall not be changed unless approved in writing by the engineer.

505.60.8 2.3 The trial slab shall become the property of the contractor after the placement plan has been

approved by the engineer and shall be removed and disposed of in accordance with Sec 202.

505.60.8 2.4 The curing and sealing of the concrete wearing surface on existing bridge decks shall be in

accordance with Sec 703.3.6.

505.60.8 2.5 The curing of the concrete wearing surface on the bottom slab of existing box culverts shall be in

accordance with Sec 703.3.6. Concrete sealer will not be required.

505.60.9 Supplementary Wearing Surface Material. Supplementary wearing surface material shall be in

accordance with Sec 505.10.9.

505.60.10 Limitations of Operations. Operations shall be limited in accordance with Sec 505.10.10.

505.60.11 Removal. Removal shall be in accordance with Sec 505.10.11.

505.60.12 Repair Repair shall be in accordance with Sec 505.10.12.

505.60.13 Measurement of Payment. Measurement will be in accordance with Sec 505.10.13.

505.60.14 Basis of Payment. The basis of payment will be in accordance with Sec 505.10.14.

SECTION 505.70 POLYESTER POLYMER CONCRETE.

505.70.1 Description. This work shall consist of constructing a polyester polymer concrete wearing surface on a

prepared surface in accordance with this specification, as shown on the plans or as directed by the engineer. Polyester polymer concrete wearing surface shall be composed of the following components – polyester resin binder, high molecular weight methacrylate (HMWM) resin and aggregate.

505.70.2 Material. All material shall be in accordance with Division 1000, Material Details, and specifically as

follows: Item Section Polyester Polymer Wearing Surface 1039

505.70.2 1 Delivery of Material. All material shall be delivered in their original containers bearing the

manufacturer’s label, specifying date of manufacturing, batch number, trade name, and quantity. Each shipment of polyester resin binder and HMWM resin shall be accompanied by a MSDS.

505.70.2 2 Storage of Material. The material shall be stored to prevent damage by the elements and to ensure

the preservation of their quality and fitness for the work. The storage space shall be kept clean and dry, and shall contain a high-low thermometer. The temperatures of the storage space shall not fall below nor rise above that recommended by the manufacturer. Every precaution shall be taken to avoid contact with flame.

505.70.2 3 Inspection. Stored materials shall be inspected prior to their use, and shall meet the requirements of

this specification at the time of use.

505.70.2 4 Failure. Any material which is rejected because of failure to meet the required tests or has been

damaged so as to cause rejection shall be immediately replaced at no additional expense to the Commission.

505.70.2 5 Required Amount. Sufficient material to perform the entire polyester concrete application shall be

in storage at the site prior to any field application, so there shall be no delay in procuring the material for each day’s application.

505.70.2 6 Training. The contractor shall arrange to have the material supplier furnish technical service related

to application of material and health and safety training for personnel who are to handle the polyester polymer concrete and the HMWM resin prime coat.

505.70.2 7 Technical Support. The materials supplier shall have a representative onsite during placement of the

polyester polymer concrete.

505.70.3 Concrete Mixture. The contractor shall prepare and submit the mix design and mixing procedures to

Construction and Materials for approval. The contractor shall not begin ordering materials until the mix design and mixing procedures are approved.

505.70.3 1 The contractor shall designate in the mix design letter what the target slump will be in the field.

505.70.3 2 The mix design shall include a recommended initiator percentage for the expected application

temperature.

505.70.3 3 Any change in mix design or proportions shall be approved by the engineer.

505.70.4 Testing. Testing shall be in accordance with Sec 505.10.4, except as specified herein.

505.70.4 1 Bond testing shall be performed for each placement on each day. Testing will be conducted at three

locations 48 hours after placement. Testing will be performed in accordance to ACI 506R. A passing test is the failure of the concrete substrate or bond strength above 250 psi.

505.70.5 Mixing. Mixing shall be in accordance with Sec 501.

505.70.6 Surface Preparation. Surface preparation shall be in accordance with Sec 505.10.6, except as

specified herein.

505.70.6 1 With approval from the engineer, the contractor may use automatic shot blasting units in lieu of sand

blasting. The automatic shot blasting units shall be self-propelled and include a vacuum to recover spent abrasive. The abrasive shall be steel shot. Magnetic rollers shall be used to remove any spent shot remaining on the deck after vacuuming. Cleaned surfaces shall not be exposed to vehicular or pedestrian traffic other than that required by the wearing surface operation.

505.70.6 2 All steel surfaces that will be in contact with the wearing surface shall be cleaned in accordance with

SSPC-SP10, Near –White Blast Cleaning, except that wet blasting methods shall not be allowed.

505.70.7 Finishing Equipment. The finishing machine shall be designed for striking off and finishing polyester

polymer concrete wearing surface. The finishing machine, screeds, traveling strike off and support rails shall be in accordance with Sec 505.10.7.

505.70.8 Placing and Finishing Concrete. Placing and finishing shall be in accordance with Sec 505.10.8,

except as specified herein.

505.70.8 1 Prime Coat. One coat of HMWM prime coat shall be applied to the prepared concrete and steel

surfaces immediately before placing the polyester polymer concrete. The prime coat shall be uniformly applied to completely cover the surface to receive the wearing surface. The area receiving the prime coat shall be dry and had no exposure to any moisture within the past 24 hours. Prior to applying the prime coat, the surface shall be cleaned with compressed air to remove accumulated dust and any other loose material.

505.70.8 1.1 The concrete bridge deck surface shall be between 50 F and 100 F when applying the prime coat.

505.70.8 1.2 If the primed surface becomes contaminated, the contaminated area shall be cleaned by abrasive

blasting and re-primed at no additional expense to the Commission.

505.70.8 2 Polyester Polymer Concrete. Polyester polymer concrete shall be placed immediately after the

prime coat is applied to the bridge deck and within two hours of placing the prime coat.

505.70.8 2.1 Polyester polymer concrete shall not be placed when the relative humidity is above 90 percent. If

placed at night, care should be taken that the relative humidity does not rise rapidly with falling temperatures.

505.70.8 2.2 The surface temperature of the area to receive polyester polymer concrete shall be the same as

specified in Sec 505.70.8.1.1.

505.70.8 2.3 Mixing. The concrete shall be volumetrically mixed at the bridge site by a continuous mixer in

accordance with Sec 501.

505.70.8 2.3.1 The continuous mixer shall be equipped with a metering device that automatically measures and

records the aggregate volumes and corresponding resin volumes. The volumes shall be recorded at no greater than five-minute intervals along with the time and date of each recording. A printout of the recordings shall be furnished to the engineer at the end of each shift. Readout gages shall be visible to the engineer at all times.

505.70.8 2.3.2 The concrete discharged from the mixer shall be uniform in composition and consistency. Mixing

capability shall be such that initial and final finishing operations can proceed at a steady pace.

505.70.8 2.3.3 The contractor shall prevent any cleaning chemicals from reaching the polyester polymer

concrete mix during the mixing operation.

505.70.8 2.3.4 Polyester polymer concrete shall be placed prior to gelling and within 15 minutes following the

addition of initiator, whichever occurs first. Polyester polymer concrete that is not placed within this time shall be discarded.

505.70.8 2.3.5 The polyester resin binder in the polyester polymer concrete shall be 12 percent ± one percent by

weight of the dry aggregate. The contractor shall determine the exact percentage as approved by the engineer.

505.70.8 2.3.6 The amount of peroxide initiator used shall result in a polyester polymer concrete set time

between 30 and 120 minutes during placement. The initial set time will be determined by using an initial-setting time Gillmore needle in accordance with ASTM C266. Accelerators or inhibitors may be required as recommended by the polyester resin supplier and as approved by the engineer.

505.70.8 2.4 Finishing equipment shall be capable of consolidating the polyester polymer concrete and striking

off the polyester polymer concrete to the final grade, thickness and cross-sections as shown in the contract documents.

505.70.8 3 Surface Texturing. The roadway surface, except within 12 inches of the inside face of the curb, shall

be textured as soon as the condition of the polyester polymer concrete will permit. The roadway finishing shall otherwise be in accordance with Sec 502. Hand-operated devices producing a satisfactory texture will be permitted. At the contractor's option, a finned float with a single row of fins may be used. The grooves produced by the finned float shall be approximately 1/8 inch wide at 5/8 to 3/4-inch centers and shall be approximately 1/8 inch deep. This operation shall be performed at such a time and in such a manner that the desired texture will be achieved while minimizing displacement of the layer aggregate particles.

505.70.9 Supplementary Wearing Surface Material. Supplementary wearing surface material shall be in

accordance with Sec 505.10.9.

505.70.10 Limitations of Operations. Operations shall be limited in accordance with Sec 505.10.10, except

that traffic and construction equipment shall not be permitted on the polyester polymer concrete wearing surface for at least two hours and until the polyester polymer wearing surface has reached a minimum compressive strength of 3000 psi as verified by the rebound number determined in accordance with ASTM C805. Rebound number shall be correlated to cylinder compressive strength through development of a calibration curve specific to the project, and as directed by the manufacturer.

505.70.11 Removal. Removal shall be in accordance with Sec 505.10.11.

505.70.12 Repair. Repair shall be in accordance with Sec 505.10.12.

505.70.13 Method of Measurement. Measurement will be in accordance with Sec 505.10.13.

505.70.14 Basis of Payment. The basis of payment will be in accordance with Sec 505.10.14.