for Highway Construction Page 372 of 71 5 SECTION 510 – CONCRETE OVERLAY
510.01 Description.
Provide and place a latex -modified concrete or a silica concrete overlay .
510.02 Materials.
Provide materials as specified in: Aggregate ..................................................................................................................................... 703 Portland Cement ........................................................................................................................... 701 Water for Concrete .................................................................................................................. 720.01 Air-Entraining Admixtures ........................................................................................................ 709.03 Water -Reducing Admixtures .................................................................................................... 709.05 Silica Fume ................................................................................................................................... 714 Fly Ash .......................................................................................................................................... 714 Fibrillated Fibers ...................................................................................................................... 720.09
A.Certification . Provide certification of the silica fume or latex modifier, taken during production or transfer, stating the test results made on the material samples meet this specification. Submit certification and test reports, indicating typical values, before use of the material.
B.Sampling and Testing. The Engineer will sample the material proposed. The Engineer will test concrete as specified in 502.02.
C.Acceptance. The Engineer will reject portland cement , latex modifier, or silica that does not meet this specification. The Engineer will report the rejection to the Contractor promptly. In cases of dissatisfaction with the test results, the Engineer will allow the Contractor additional sampling and retesting. The Engineer’s acceptanc e of the concrete overlay will be based on compliance with parameters specified. The Engineer will determine acceptance of strength from the results of 28- day compressive strength tests, performed in compliance with 502.02, on cylinders made from samples of the concrete being plac ed. The average strength from 3 companion cylinders is 1 test. If the 28 -day strength falls below the specified minimum strength, the Engineer may reject the concrete represented by the test or require a price adjustment if allowed to remain in p lace. The Engineer will base acceptance on an evaluation of the necessary durability requirements of the concrete overlay . The Engineer may accept concrete that does not meet the specified minimum strength, at a reduced price if the strength is not more than 10 percent below the specified minimum strength. The Engineer will reject concrete represented by tests falling more than 10 percent below the specified minimum strength. Remove rejected concrete at no additional cost to the Department. The Engineer will adjust the price for the concrete overlay that does not meet the specified strength, but is allowed to remain in place as presented in Tabl e 510.02 -1. for Highway Construction Page 373 of 71 5 Table 510.02 -1 – Price Adjustment Percent of Specified Strength Pay Factor ≥ 95 to < 100 0.90 ≥ 90 to < 95 0.80 The Department will pay for the quantity of acceptable concrete overlay at the contract unit price multiplied by the pay factor. The Contractor may remove and replace concrete overlay that has a pay factor of less than 1.0 at no additional cost to the Department.
D.Storage . Store the material to allow easy access for proper inspection and identification of each shipment. Allow the Engineer to access every facility, at the source and at the project site, for sampling and inspection. Protect material from freezing and from prolonged exposure to temperatures in excess of 75°F. Cover containers stored at the bridge site completely with suitable insulating blanket material to avoid excessive temperatures.
E.Packaging . When material is delivered, plainly mark the name and brand of the manufacturer and the material weight on each container. Identify shipments by source and lot number. Use only one manufacturing source when available. If this is not available, obtain approval from the Engineer. Submit similar information on the shipping invoices accompanying the material shipment. Ensure containers are in good condition at the time of inspection . Provide size No. 1 coarse aggregate for latex -modified concrete . Ensure the latex modifier contains at least 46 percent solids. Determine the percent solids by tests using Idaho IT 121. Submit certification from the producer indicating the material provided is identical to that provided to the FHWA Fairbanks Highway Research Station. Provide latex -modified concrete that meets the following properties: Table 510.02- 2 – Latex -Modified Concrete Properties Mix Design Item Requirement Cement content 660 lb/yd3 Latex emulsion admixture 25 gal/yd3 Approx. added water (a), including free moisture in the FA & CA 150 lb/yd3 Air content, percent of plastic mix 0 - 6.5 Slump(b) 4 - 6 in Percent fine aggregate as percent of total aggregate by weight (rounded CA) 55 ± 5 Percent fine aggregate as percent of total aggregate by weight (crushed CA) 60 ± 5 for Highway Construction Page 374 of 71 5 Mix Design Item Requirement Weight ratio of cement -FA-CA- (rounded CA)(c) 1:2.5:2.0 dry basis Weight ratio of cement -FA-CA- (crushed CA)(c) 1:2.7:1.8 dry basis 28-day compressive strength (Minimum) 4,000 psi
a.This is in addition to the latex. Adjust the water added to control the slump and to produce net water -cement ratios of 0.35 to 0.40 by weight.
b.Measure the slump 4 to 5 minutes after discharge from the mixer or immediately ahead of the finisher.
c.The Contractor may adjust the dry -weight ratios within limits as approved. The Contractor may increase the FA ratio by as much as 0.2 if the CA is reduced by an equivalent amount. Provide silica fume concrete with the following properties: Table 510.02- 3 – Silica Fume Concrete Properties Mix Design Item Requirement Cement Content (Minimum) 520 lb/yd3 Water/(Cement + Silica Fume) Ratio (Maximum) 0.40 Course Aggregates Size No. 1 Slump 5 in plus or minus 2 in Air Content 6% plus or minus 2% High-Range Water Reducers (rounded CA) ASTM C494 7-Day Compressive Strength (Minimum)(a) 3,500 psi 28-Day Compressive Strength (Minimum)(a) 4,500 psi Percent Silica Fume by Weight of Cement 7.5% minimum Percent Fly Ash (if used) of total cementitious 15% minimum Fibrillated fibers 1.5 lb/cy minimum
a.Overdesign is limited to a maximum 6,500 psi when produced in a laboratory. Cementitious material content may be reduced to meet the overdesign limits. The Engineer will waive the overdesign if the Cont ractor reduces the cementitious materials content by at least 10 percent.
b.The concrete mix must be tested according to 409.02 for expansion limits. Provide the silica fume admixture as a densified powder.
510.03 Const ruction Requirements.
A.General. The Department will require the Contractor and a technical representative from the silica fume/latex -modified concrete supplier to meet with the Engineer for a pre- placement conference at a time mutually agreed upon. At or before this conference, present the mix design and methods of accomplishing the concrete overlay work. Allow the Engineer 15 calendar days to review the mix design. for Highway Construction Page 375 of 71 5 Ensure technical representatives from the latex admixture manufacturer/silica fume supplier and high- range water reducer are present during the proportioning, mixing , placing, and finishing of the concrete overlay . One person may perform both of these functions. Ensure this technical representative has expertise in the proper installation of the materials and is available to the Engineer for consultation. Adhere, at no cost to the Department, to the written instructions and/or recommendations made by the technical representative and as approved. Before placement , prepare, place, and cure a trial batch of at least 3 cubic yards to verify the mix design , show ability to perform curing operations, and check quality control. Make additional trial batches as necessary to verify changes in design or procedure at no additional cost to the Department. Provide rails for the finishing machine to travel on that are sufficiently rigid so they do not deflect under the weight of the machine. Attach the rails to the surface so they may be removed without damage to the edge of the new overlayment. Provide rails that are vertically adjustable (not shimmed) and adjust using a level and level rod to ensure proper depth and matching of joints . Set the screed control to obtain the nominal overlay thickness specified as well as finished surface smoothness requirements. Verify the thickness before the placement of the concrete by attaching a filler block to the bottom of the screed. With the screed guides in place, pass the fini shing machine over the surface to be overlaid. After the overlay thickness has been verified, adjust the profile grade as directed or approved. Do not change the finish machine elevation controls.
B.Equipment. Use an approved power -driven finishing machi ne for finishing areas with a width equal to or greater than 14 feet complying with the following requirements:
1.Have at least 2 hand- operated, spud type internal vibrators available for use as directed. Submit a request for approval of the specific equipment to be used at least 15 calendar days before the start of work. Do not begin placing deck concrete until the screed and placing procedure is approved.
2.Provide a self-propelled finishing machine capable of forward and reverse movement under positive control for placing, striking off, and finishing the bridge deck surface with provisions for raising screeds to clear the surface. Equip the machine with vibrating screeds designed to consolidate the modified composition. The Department requires the vibration frequency be variable with positive control between 3,000 and 11,000 vibrations per minute and the bottom face of the screeds be at least 4 inches wide and be metal covered. Provide screeds with positive control of the vertical position. Equip the finishing machine with 1 or more rollers, augers, and 1,500 or 2,500 vibration per minute vibratory pans. Provide a Bid- Well 2450 or equivalent finishi ng machine. Modification to the Bid- Well 2450 or equivalent is subject to approval.
3."Texas", "Allen", or "Bunyon" type screeds will not be allowed unless otherwise approved for small and/or irregular areas.
C.Deck Preparation . Remove the concrete deck surface as specified in 632 before placing the concrete overlays. Use approved temporary bridge drain plugs during preparat ion and placement to prevent waste materials from entering drainage systems. Protect expansion joints and barrier curbs by approved means from damage due to construction operations. Remove the concrete deck by hydrodemolition. for Highway Construction Page 376 of 715 Not more than 24 hours before placi ng the overlay, clean surfaces the overlay is to bond to, including exposed reinforcing and structural steel , the work face of the previously placed material, and the faces of curbs and barriers up to a height of at least 1 inch above the proposed overlay surface, by abrasive blasting or an approved method of waterblasting with 7,000 psi minimum pressure. Blow the deck with compressed air to remove excess water and debris. After the deck has been airblasted, cover the deck with unused, 4 mil plastic sheeting. Clean steel surfaces to meet the requirements of 708.01. Ensure concrete surfaces are made without spalls, laitance, and contaminants detrimental to achieving a dequate bond. Provide water and oil traps on the compressors. After the surface is properly prepared, do not allow vehicular traffic other than equipment required to place the overlay. Do not exceed construction loads of 8,000- pound wheel load or 16,000- pound axle load. Combination of axles placed closer than 4 feet center -to-center is evaluated as 1 axle. Operate equipment required on the deck for placing the overlay on plastic sheeting or diaper the equipment to prevent dripping fluids from contaminating the prepared surface.
D.Mixing .
1.Latex -Modified Concrete. Use continuous -mixing type mixers complying with the following:
a.The mixer carries sufficient cement, fine aggregate , coarse aggregate, latex modifier, and water to produce at least 6 cubic yards of concrete.
b.The mixer is capable of positive measurement of cement being introduced into the mix. A visible recording meter equipped with a ticket printout to show the quantity accurately is required.
c.The mixer provides positive control of the flow of water and latex emulsion into the mixing chamber. Water flow is shown by flow meter and is readily adjustable to provide for minor variations in aggregate moisture.
d.The mixer is calibrated to automatically proportion and blend components of shown composition on a continuous or intermittent basis as required by the finishing operation, and discharges mixed material directly in front of the finishing machine.
e.At least 2 mixers are used for each placement if the total volume of concrete to be placed exceeds the material storage capacity of a single mixer . The Engineer may require additional mixers if conditions requi re materials be stockpiled away from the project site. Have sufficient mixers on hand t o ensure a consistent and uniform delivery and placement of concrete.
f.The mixer is equipped with a bypass valve to enable calibration of the water valves or flow meters.
g.Verify the fine aggregate bin vibrators are oper ating satisfactorily. Calibrate mixers to accurately proportion the specified mix. The Engineer will accept certification of the calibration by an approved testing authority as evidence of this accurac y if the yield is shown to be true within a tolerance of 1.0 percent using the following test:
a.With the cement meter set on zero and controls set for t he desired mix, activate the mixer , discharging mixed material into a 0.25 cubic yard container.
b.When the container is level -struck full, making provision for settling the material into corners, the Department requires the cement meter to show a discharge of 1.75 sacks of cement for latex - modified concrete, 7 s acks per cubic yard. for Highway Construction Page 377 of 715 Ensure the concrete discharged from the mixer is uniform in composition and consistency. Finishing operations must proceed at a steady pace with final finishing completed before the formation of the plas tic surface film.
2.Silica Fume . Calibrate mixers to accurately proportion the specified mixture. Provide a visible recording meter equipped with a ticket printout to show the quantity accurately. Ensure the silica fume m anufacturer’s technical representative advises the Engineer in writing of proper batching sequence, mixing time, mixing speed, and other handling procedures necessary for a uniform, homogeneous mixture meeting the requir ements of this section . Include procedures relating to the high- range water reducer. Follow the written instructions. Do not exceed 6 cubic yards of silica fume concrete in the truck mixer . If a truck mixe r or agitator is used for transporting silica fume concrete , complete discharge within 1 hour and 45 minutes or before the drum has revolved more than 325 revolutions, whichever comes first, after introduc tion of cement and water. Obtain approval to use a set stabilizer if haul times exceed 1 hour and 15 minutes. If a set stabilizer is used, the mixing revolutions may be increased to 500 revolutions and discharge time increased to 3 hours. If a slurry is used, adjust mix water to account for the water in the silica fume slurry and store the product in a tank with an agitator so t he product can be mixed in accordance with the manufacturer’s written instructions. If placement is done during cold weather, insulate or protect the tank against freezing.
E.Placing and Finishing. During pl acement of the overlay, ensure the surface of base concrete is in a saturated surface dry condition. Achieve this by thoroughly wetting the surface at least 12 hours before placement and maintaining it in a moist condition until placement. Maintain a moist condition by covering with visqueen and/or usin g fog spray or soaker hoses provided that complete moisture coverage is attained. Blow out standing water in depressions, holes, or low areas with compressed air before the application of the bonding coat. Promptly deliver and deposit on the deck a bonding coat consisting of a portion of the overlay mix on the deck then scrub by brooming onto the wetted, prepared surface. Do not use separately mixed bonding coats. Exercise care to ensure vertical and horizontal surfaces receive a thorough, even coating. Limit the rate of progress to no more than 6 feet ahead of the screed so the brushed material does not become dry before it is covered with the finish course. Dispose of materials intended for brushing that have started ini tial set, d ried, or show evidence of loss of paste from the sand. Dispose of coarse aggregate remaining after the brushing operation. Manipulate the material and strike off to approximately 1/4 in ch above final grade. Consolidate the material and finish at final grade with the vibrating screeds. Hand- finish with a wood float along the edge of the pour or on small areas of repair. In areas requiring hand finishing and areas adjacent to curbs and joi nt bulkheads, use vibrators to ensure proper consolidation. Install a construction dam or bulkhead in case of major delay in the placement operation. During minor delays of 1 hour or less, protect the end of the placement from drying with several layers of wet burlap. Construct longitudinal joints at or within 1 foot of lane lines . When concrete is to be placed against concrete in a previously placed lane or strip, saw the pr eviously pl aced concrete back the necessary distance to provide a straight and vertical edge. The Contractor may omit sawing of the joint if bulkhead produces a for Highway Construction Page 378 of 71 5 straight, smooth, and vertical surface. Sandblast, clean, and apply a bonding coat before placi ng new conc rete. Do not place concrete against the edge of an adjacent lane or strip that is less than 24 hours old. Take adequate precautions to protect freshly placed material from sudden or unexpected rain. The Engineer may order removal of mate rial damaged by rainfall. Do not place the concrete overlay when the evaporation rate is greater than 0.15 pounds per square foot per hour when tested in accordance with Idaho IT 133, unless the Contrac tor can show by reducing the spread width or by other means that a satisfactory surface finish can be obtained. Do not place the concrete overlay at ambient temperatures lower than 45°F or higher than 75°F. When a tight uniform surface has been achieved, texture the surface of the concrete perpendicular to the longitudinal centerline of the structure with an approved grooving tool. Ensure nominal groove width is 1/8 in, with spacing of ½ to ¾ inch and the depth of tined grooves is of 5/32 inch plus or minus 1/32 inch deep. Check groove depth in accordance with Idaho IT 147. If more than 3 readings in a set of 10 are outside the intended depth range, make adjustments to the tining operation. The Contractor may apply an approved wire tine texture providing it leaves a finish comparable to the groove depth and spacing specified and causes only minimal surface tearing or aggregate removal. Finish the surface adjacent to the curb to a smooth- troweled texture approximately 1 foot from the face of the curb. Apply a continuous fog spray of water to screeded and finished concrete. Provide fogging equipment for spreading a fine mist over concrete surfaces without ponding water. Continu e fogging behind the final floating operation until placement of the cure system, and as directed. Do not fog concrete surfaces to aid surface finishing
F.Curing. Promptly cover the surface with a single layer of clean, w et burlap. Exercise care so the burlap is not dragged or dropped on the fresh surface. Ensure the burlap is drained free of water and that it is placed as soon as the surface will support the covering without deformation. Do not wait until the surface will support foot traffic. The concrete overlay forms a plastic film at the surface on drying, usually within 20 minutes in hot, dry weather. Protect the plastic film from over -drying and cracking by promptly covering with the wet burlap. Maintain the burlap in a wet condition throughout the duration of the wet cure. Unplug the deck drains to allow drainage to pass through. Place a layer of 4 mils polyethylene (PE) film on the wet burlap for the required wet -cure period within ½ hour of covering with wet burlap. The Contractor may substitute approved burlap- PE sheets for the PE film. Wet-cure the latex -modified concrete for at least 48 hours. Remove the curing material for an additional 72- hour dry -cure period. Extend the dry curing period in case of rainfall or dampness to ensure the surface of the concrete has a total of 72 hours of dry curing. Wet-cure the silica fume concrete for at least 4 calendar days. Use a work bridge to place the burlap and PE. Do not walk on the overlay during placement of these items. Do not allow traffic on the silica fume concrete surface until the 4- day wet cure is complete and the silica fume has a minimum compressive strength of 3,500 psi. Do not allow traffic on the latex concrete surface until completion of the dry -cure period. The Engineer may require a longer curing period at temperatures below 55°F. On completion of the wet cure of the last section overlaid, immediately treat visible cracking with a 2-component modified methacrylate penetrating sealer. Spread sand over areas on surface where sealer has for Highway Construction Page 379 of 71 5 puddled in an amount to ensure adequate skid resistance. The SikaPronto 19 and Transpo Sealate T70- X are acceptable sealers or others as approved. Meet the smoothness requirements specified in 409 for the finished concrete overlay surface. After the concrete overlay has cured, the Engineer will use a chain drag or other appropriate tool or device to determine if delaminations exist between the new overlay and the mating concrete surface. Remove and replace delaminated areas. The Department will require vertical edges and rectangular -shaped patching if removal is necessary. When smoothness grinding is enforced, seal the ground areas with an approved sealer.
510.04 Method of Measurement.
The Engineer will measure acceptably completed work by the cubic yard as recorded on approved batch tickets. The Engineer will reject batch tickets for unacceptable material or excessive waste quantities .
510.05 Basis of Payment .
The Department will pay for acceptable quantities as follows: Pay Item Pay Unit Concrete Overlay .................................................................................... CY If the volume used exceeds the neat line volume by more than 10 percent, the Department will pay for the volume exceeding 10 percent of the neat line volume at 50 percent of the contract unit price. The Department will pay for concrete overlay that does not meet the specified minimum strength and is allowed to stay in place by the Engineer as specified in 510.02. The Engineer will deduct from the contract unit price of the concrete overlay and apply the adjusted contract unit price to the qu antity of concrete overlay represented by the individual strength test. The services of the technical representatives are incidental . for Highway Construction Page 380 of 715 SECTION 511 – CONCRETE WATERPROOFING SYSTEMS
511.01 Description.
Provide concrete waterproofing systems and install on bridge deck s or other designated surfaces.
A.System Types . Use one of the following system types :
1.Type C Penetrating Water System. Sealant that penetrates the bridge deck surface and forms a water -repellant layer within the co ncrete .
2.Type D Precoated, Preformed Membrane Sheet System. Prefabricated sheets that are self - adhesive or require a separate bonding agent.
3.Type E Spray -Applied Waterproofing System. Suitable for concrete or miscellaneous metal surfaces to prevent corrosion from soluble salts on the bridge deck and approach slabs that are to be overlaid with asphalt .
B.Qualifications.
1.Manufacturer Representative. Provide the services of a manufacturer' s representative authorized to observe the installation of each membrane system, including the asphalt concrete wearing course . The manufacturer's representative must be an employee of the membrane system manufacturer. Do not begin membrane work until the manufacturer's representative is onsite and authorizes the work to begin. Follow the manufacturer's written instructions when installing the spray membrane system, as provided in this specification. Instruct th e manufacturer's representative to alert the Contractor and the Engineer of anything that could affect the performance of the spray waterproofing membrane or the warranty. Submit a daily written report that has been prepared by the manufacturer's represe ntative and details all membrane- related activities, test results, observations, repairs , postspray survey results, tack coat timing issues, and contaminated tack repairs. Submit the daily written report by th e end of each day until the work is complete.
2.Applicator Qualifications. Provide a manufacturer -authorized applicator. Applicators must be re- certified annually by the manufacturer.
3.Submittals. Begin work no earlier than 1 week after the following items are approved:
a.The manufacturer must provide independent laboratory test illustrating each component’s accordance to the physical property requirements listed in Tables 511.02- 1, 511.02- 2, and
511.02 3. All testing must be current (i.e., conducted within the past 3 years).
b.The manufacturer’s safety data sheet (SDS) for each of the components.
c.The manufacturer’s current product data sheets and installation details for the product. Provide all membranes and primers f rom the same manufacturer.
d.Two sample coupons (3”x6”) that are representative of the finished membrane surface, texture, and color. Approved samples will serve as a basis for acceptance of the work for the duration of the contract .
Source: Idaho Standard Specifications for Highway Construction, 2023 Edition. Pages 408–415 of 768.