A Specification Model for Latex (polymer) Modified Concrete

Specification for latex (polymer) modified concrete bridge deck overlay for new and existing bridges.


This work shall consist of constructing a Latex Modified Concrete (LMC) bridge deck overlay for the purpose of protecting the underlying structural concrete from the deterioration caused by absorption of vehicular chemicals, sea salts, deicing salts and water. This work includes all labor, materials, equipment and incidentals, and shall be performed in reasonably close conformity with the Plans and these specifications.


Materials used in this construction shall meet the following requirements in addition to the general requirements of these Specifications:

  • Portland Cement - Type I, Type III ASTM C-150 or Very Early Strength Cement
  • Latex (Polymer) Modifier - BASF Sytrofan 1186 or Styron Mod A – FHWA -RD-78-35
  • Fine Aggregate - Concrete Sand - ASTM C-33
  • Coarse Aggregate - Washed Size 7, 8, 9m, 11, 78m, CA13 or CA-16 - ASTM C-33  
  • Water - potable - ASTM C-685


The LMC mixture shall contain no less than 390 kilograms per cubic meter  (658 pounds of cement  per cubic yard) and shall be accurately proportioned as follows:

  • Cement - 94 lbs.
  • Latex Admixture - 3.5 gals.
  • Fine Aggregate - 210 to 255 lbs. (50-60% fine aggregate by total wt.)
  • Coarse Aggregate - 208 to 168 lbs.
  • Water - 0 gal. to 2.9 gals. (2.5 gals)

The properties of the LMC shall be as follows:

  • Slump – measured 4-5 minutes after discharge from the continuous mobile mixer from 75mm to 175mm  (3 inches  to  7 inches)
  • Air Content  0-8%
  • Water-Cement ratio maximum 0.40 (0.42 for VES) considering all non-solids a part of the water

The yield check shall be performed using ¼ cubic yard box method as follows:   Clean the chute of any LMC and position the box to receive the discharge of ¼ cubic yard count of concrete. The mixer shall be operated until the cement meter counter indicates that ¼ cubic yard has been produced. The contents of the box shall be consolidated and struck off. If the box is not full, the gates shall be adjusted and the procedure repeated until the actual and calculated volumes of concrete agree. Yield test shall be run on the first and third load of each mixer.   

The latex admixture shall contain a minimum of 46% solids.  The desired strength is 20.7 MPa (3,000 psi) in 7 days. The contractor shall submit in writing a concrete mix design and sources to the Department for approval. The name and location of the aggregate suppliers and the brand of cement and latex proposed for use shall be included. No change in materials will be permitted unless approved by the Engineer in writing.

Storage and Handling of Materials

Fine and coarse aggregates shall be stored and handled avoiding contamination and maintaining uniform moisture content. Fine and coarse aggregate stored in piles or bins shall remain separated and covered with a moisture proof material to assure uniform moistures in the aggregates.

Cement shall be stored in weather tight bins or silos which protects the cement from dampness. Cement shall be subjected to low–pressure aeration with dry air or to vibration to avoid bridging that will impair flow rates.

The latex shall be stored in accordance with manufacturer’s recommendations. The latex modifier should not be subjected to freezing conditions. In hot weather, steps may need to be taken to keep storage containers in cool or shady areas to minimize the temperature of the latex.


Equipment and tools necessary for handling materials and performing all parts of the work shall be approved by the Engineer as to design, capacity and mechanical condition. Equipment shall be on hand sufficiently ahead of the start of construction operations to be examined and approved.


A self-contained, self propelled continuous type mobile mixer calibrated to accurately proportion the specified mix, will be used to mix and discharge the LMC overlay.  Sufficient mixing capacity or mixers shall be provided to permit the intended pour to be placed without interruption. The mixer shall carry sufficient quantities of unmixed ingredients to produce at least 6 cubic yards (4.6 m3) of latex modified concrete at the bridge site. The mixer shall measure and control the flow of ingredients being introduced into the mix and shall record these quantities on an approved visible recording meter equipped with a ticket printer. Water flow shall be readily adjustable to compensate for minor variations in aggregate moisture content that shall be displayed by an approved flow meter. The flow of the latex modifier shall be displayed by an approved calibrated flow meter. The latex system shall also be equipped with a latex strainer to remove any solid particles during the operation of the mixer. The latex strainer should be checked and cleaned as needed. The aggregate bins shall be clean and the bin vibrators shall be in good working order. The mixer should be equipped with a grounding strap. The cement meter feeder fins and all pockets shall be clean and free of accumulated cement. The cement aeration system shall be equipped with a gauge or indicator to verify the system is operating. The main belt, latex strainer and the auger shall be free of accumulated material.

Placing and Finishing Equipment

Placing and finishing equipment shall include hand tools for placement and the brushing in of freshly mixed latex (polymer) modified concrete and for distributing it to the correct level for striking off with the finishing machine. The finishing machine shall be a self-propelled and capable of positively controlled forward and reverse motion. Provisions shall be made for raising all screeds to clear the finished surface while traveling in reverse. The machine shall be equipped with appropriate finishing devices. The first being a vibrating pan for consolidating the mix. The vibrating pan shall be metal and sufficient size to properly consolidate the mix. Spud vibration shall be used in areas the vibrating pan can not finish, such as:   gutter lines, deep patches, and at bulkheads or joints. A second finishing device shall either be a rotating cylindrical roller with augers or a vibratory-screed type with a bottom face of 4 inches wide designed to consolidate the modified composition by vibration. Vibration frequency for the pan vibrator and screed shall be variable with positive control from 1500 vibrations per minute to 7000 vibrations per minute. The third finishing device should be the pan drag, wet burlap drag or both as needed. As many as two suitable lightweight or wheeled work bridges shall be used behind the finishing machine.

Scarifying Equipment

Scarifying equipment shall be a power operated, mechanical milling machine or grinder capable of uniformly removing the existing concrete to the depth required.

Hydrodemolition Equipment

The hydrodemolition equipment shall consist of a filtering and pumping unit operating with a self-propelled computerized robot that utilizes a high pressure water jet capable of removing concrete to the depth specified on the plans or as directed by the Engineer and be capable of removing rust and concrete particles from reinforcing steel. The equipment shall provide a rough and bondable surface and remove all unsound concrete during the initial pass. The minimum water usage shall be 55 gal/hr operating at 13,000 psi minimum.

Blast Cleaning Equipment

Blast cleaning equipment (7000 psi min.) shall be capable of removing:  scale and rust from reinforcing bars,   unsound concrete, surface laitance layer, any dirt, oil and paint and to expose fine and coarse aggregate on new concrete surfaces.


The continuous mobile mixer shall be calibrated to the satisfaction of the Engineer prior to starting work. The frequency of calibration will be determined by the Engineer. All special equipment required for calibration shall be furnished by the contractor. The calibration sheets may be provided by the Department or the mixer operator.

The mixer shall be set at the appropriate operating revolutions per minute as determined by the mixer manufacturer or mixer operator. The unit discharging the cement shall be operated until an even flow of cement has been discharged. It shall then be stopped and the cement meter reset to zero. A suitable container shall be set below the discharge of cement. The time required to discharge 94 lbs. (43 kg) cement shall be measured with a stop watch, the number of counts on the cement meter shall be recorded, and the weight of the discharged cement determined. The process shall be repeated at least three times or until trials have proved consistent with one another.

With the mixer set at the required operating rpm, calibrate the delivery of the latex modifier into a suitable container.    The latex throttling valve shall be adjusted to deliver the required amount of latex emulsion admixture for each 94 lbs. (43 kg) of cement. For the calculated seconds per 94 lbs. of cement the latex shall be discharged into a container. The weight of the latex shall be determined and the throttling valve adjusted such that the amount of latex discharge is within 0.5 lb. of the weight of latex of 29.4 lbs.,  the amount required per 94 lb. of cement or 3.5 gallons per 94 lb. of cement. (Based on the latex being 8.4 lbs. per gallon)

With the mixer set at the required operating rpm, calibrate the accuracy of the water flow meter into a suitable container. The accuracy of the water flow meter shall be verified by setting the flow meter at 2 gallon per minute and discharging into a container during a one minute interval. Weighing the amount and dividing by 8.33 will determine the number of gallons. This procedure shall be repeated with the flow meter adjusted to 3 gallons per minute. A theoretical water setting on the flow meter can be determined by calculating total water required according to the mix design and then deducting for aggregate moisture and water in the latex emulsion.

Based on the approved mix design the aggregates shall be weighed out separately to meet the desired weights per cubic yard. The seconds per bag of cement for each mixer may be reduced by one half to reduce the weight of aggregates per bag to one half for more manageable handling. Yield checks shall be performed using a 36” x 36” x 9” open box to verify gate settings.

Continuous mobile mixers which entrap unacceptable volumes of air shall be allowed to use anti-foaming additive as prescribed by the latex emulsion manufacturer. Batch type mixers will not be used. Drum type mixers or rotating drum batch mixers shall not be used under any circumstances. The continuous mixer shall be kept clean and free of partially dried or hardened materials.

Construction Requirements

Bridge deck repairs and LMC overlays shall be made as soon as practical following the removals of the deck surface, pouring full depth patching, performance of Hydro-demolition as specified and all necessary final deck cleaning. Traffic will not be allowed on any deck surface until final curing is completed in accordance with these specifications.

Deck or Surface Preparation Methods

  • Scarifying: the entire bridge deck surface shall be removed to a minimum of ¼ inch if the bridge deck was constructed under a previous contract. After initial surface removal an additional ¼ inch may be removed as directed. On decks that have received an initial overlay, the entire overlay shall be removed and  an additional ¼ inch of the existing bridge deck surface milled or scarified. This operation may be completed in one pass. All surface residual, including water, dust, and concrete must be removed immediately.
  • Hand-chipping: Following cleanup of surface removal operations the entire bridge deck surface shall be sounded for bad concrete. The areas of unsound concrete shall be marked and removed. Unsound areas shall be removed by hand-chipping or hydro-demolition. Jack hammers shall not heavier than the nominal 45lb. class and chipping hammers shall not heavier than the 15lb. class. Only hand-chipping hammers may be used when removing concrete within 1 inch of reinforcing steel.  Where the bond  between the reinforcing steel and the existing concrete is destroyed the concrete adjacent to the steel shall be removed to a minimum clearance of 1 inch. Several soundings may be necessary to assure removal of the unsound concrete. Cleanup of all areas will be performed prior to resounding.
  • Hydrodemolition: The hydrodemolition machine shall utilize a high pressure water jet system and shall be approved prior to use. The hydrodemolition equipment will be calibrated to only remove unsound concrete and to provide a highly bondable surface for the new overlay. The calibration of the equipment shall be re-performed on each structure. Precautions shall be taken during the hydrodemolition operation to prevent damage to surrounding property and traffic. Do not allow waste water to dry on the bridge deck surface.

Regardless of the removal method being used, the removal operation shall be stopped if it is determined that sound concrete is being removed. Recalibration of equipment or alternative changes in equipment or practice shall be performed before resuming removal operations.

Blast Cleaning

Before the overlay is placed the entire deck surface and any related vertical surfaces of the concrete curbs, patches, parapets or barrier walls shall be cleaned to one inch above the top surface elevation of the overlay. The deck surface shall be thoroughly blast cleaned by sand-blasting, shot-blasting or high pressure water-blasting of 7,000 psi minimum the preferred method after hydro-demolition. The deck surface shall be clean and free of any laitance, oils, dirt, grease, paint, bituminous matter, rust or any foreign substance prior to the placement of the overlay. Expose the fine and coarse aggregate if pouring on new concrete surfaces.

All debris of any type, including dirty water from water-blasting shall be contained and completely removed or flushed from the entire deck surface. The deck surface shall not be allowed to dry out after water-blasting operation has been completed. Any method which does not consistently produce satisfactory work and conform to the above requirements shall be discontinued and replaced by an acceptable method.  The entire surface shall be covered with plastic after cleaning operations have been completed. The Engineer may direct that blasting operations be repeated if the overlay placement is not performed within 36 hours or any part of the deck has dried out at the contractors expense.

Placement and Finishing Limitations

Prior to the placement of the overlay the Engineer shall establish the Contractor’s ability to place the overlay on a continuous basis and to consolidate, finish, texture prior to the formation of the plastic surface film and the commencement of curing procedure.   Operations or procedures which are considered to be detrimental to the integrity and durability of the repaired and overlaid bridge deck will not be permitted.

Expansion joints shall be maintained throughout placement of the overlay. A bulkhead equal in thickness to the width of the joint shall be installed to the required grade and profile, prior to placing the overlay. The screed rails for the finishing machine shall be placed and anchored vertically and horizontally to secure the required specification profile. Screed rails shall not be treated with any bond breaking compound.

After the screed rails have been set to proper profile. The finishing machine shall be given a dry run to assure that the specified nominal thickness of the overlay will be attained over the entire deck.

After the surface has been cleaned and prior to the overlay placement the deck surface shall be thoroughly wetted with potable water for a period of not less than one hour or as many as 6 hours if needed to cool the deck temperature in hot weather. Once the deck is wet, cover with plastic to keep clean and prevent surface evaporation. No deck evaporation should be occurring prior or during placement of the overlay. Remove all standing water from the deck surface prior to starting placement. Use vacuums or oil-free compressed air to remove any standing water during the overlay placement. 

LMC shall be mixed at the job site in accordance with the specified requirements for the equipment used. The maximum time between mixing and placement shall not exceed 20 minutes. Mixing capability shall be such that the finishing operations can proceed at a steady pace with final finishing completed before formation of the plastic surface film. Keep the wet burlap (non-dripping) within 20-30 feet of the finishing operation and place white plastic over the burlap as soon thereafter as possible. Misting the burlap prior to placing the white plastic is suggested.

The overlay should not be placed unless the ambient temperature is 45 degrees F and rising and predicted temperatures will be over 45 degrees F over the duration of the placement without the written approval of the Engineer. Protection of the overlay shall be made to assure the overlay remains above 45 degrees F for the duration of the cure period prior to opening to traffic or the specified compressive strength whichever comes first. If during wet or dry cure periods the ambient temperatures fall below 45 degrees F, the number of hours that the temperature falls below 45 degrees F will not be considered part of the 96 hour cure period. Also, during the dry cure period if rain occurs to wet the surface for one hour or more the number of hours will not be considered part of the dry cure period.  Do not allow the overlay surface to freeze prior to the end of the cure period or until proper compressive strength is achieved.

Placement may be required to be made during early morning hours, late night or other limited time frames when daytime temperatures exceed 85 degrees F. No overlay shall be placed when temperatures or concrete are above 85 degrees F without the approval of the Engineer. A machine mounted fogging device will be required on all finishing machines.

The overlay should not be placed if rain is expected. Adequate precautions should be taken to protect the freshly place overlay material from sudden or unexpected rain. Damaged material will be removed and replaced with no additional payment. A construction dam or bulkhead shall be prepared and placed if delays of one hour are expected. Delays of less than one hour wet burlap shall be placed on the leading edge of the overlay to keep from drying out.

The LMC should be stiffly broomed onto the wet prepared deck surface in a good thick paste just ahead of the overlay placement. All horizontal and vertical surfaces should receive a thorough even coating of LMC. Do not let this material dry out prior to covering with additional material for final placement and grade. Any loose aggregate that has lost its grout paste must be removed from the deck surface and disposed of. Brooming is not necessary on hydrodemolition prepared surface.

All areas that cannot be reached by the finishing machine vibrator shall be spud vibrated. Curb lines, variable depth patches, joints or dams shall be vibrated. Hand finishing with a float will be required along the edge of the placement or in small areas.


When pre-cure texturing is specified and a tight uniform surface has been achieved, it shall be textured immediately after finishing and before the plastic film forms. The transverse grooves shall be formed by specified texturing equipment and shall be terminated at a specified distance from the face of the curb or barrier wall. The grooves shall be relatively uniform and smooth, and shall be formed without tearing the surface and without exposing or bringing pieces of coarse aggregate to the surface.

Mechanical grooving is to be completed after the dry cure process or specified cylinder strengths are achieved.


  • The surface of the overlay shall be promptly covered with a single layer of clean wet burlap as soon as the surface will support it without deformation usually within 15-20 minutes after placement.
  • Cover the wet burlap with a layer of white polyethylene film of 4 mil thickness for the entire duration of wet cure.  
  • Keep burlap continuously wet during the length of the wet cure. In hot temperatures soaker hoses shall be used to cool the overlay under the white plastic and an extended wet cure of 24 hours is suggested.

Cure durations:

  • Type I Cement LMC Mix = 24 hrs wet / 72 hrs dry
  • Type III Cement LMC Mix = 24 hrs wet / 24 hrs dry
  • Rapid Set Cement LMC Mix = 3 hr wet / = 2,500 psi

MC Essentials

Latex modified concrete has stood the test of time. Because of its high quality, latex concrete is a very forgiving product. The essential parts of a quality LMC overlay:

  • Fulfilling specifications of the LMC
  • Proper bridge deck preparation
  • Proper installation
  • Proper cure

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