1042LATEX MODIFIED MORTAR OR CONCRETE WEARING SURFACE

1042.1DESCRIPTION—This work is construction of a latex modified mortar or concrete wearing surface

on bridge decks , approach slabs or indicated surfaces . The indicated or specified depth of the wearing surface is the minimum.

1042.2MATERIAL—

less than 1 1/4 inches. Use latex modified concrete when the depth is 1 1/4 inches or more. Provide a concrete technician as specified in Section 704.1(d)2. Provide testing facilities and equipment as specified in Section 704.1(d)3. The term “latex,” as used in this Section, refers to latex modified mortar or concrete, unless otherwise specified. Provide latex conforming to the following requirements:

Latex Modified Mortar or Concrete Mix Design Requirements Requirements Mortar Concrete

Cement Content, bags/cu. yd. 8.0 7.0 Latex Emulsion Admixture Modifier, gal/bag of Cement 3.5 3.5 Air Content, % of Plastic Mix (AASHTO T 152) 1 - 7 1 - 7 Water/Cement Ratio, by Weight 0.35 - 0.40 0.30 - 0.40 Slump(1), inches (AASHTO T 119) 4 - 6 3 - 7 Percent Fine Aggregate as Percent of Total Aggregate, by Weight 100 60 ± 5 Cement/Fine Aggregate/Coarse(2) Aggregate Ratio, by Weight 1:3.25 1:2.5:2.0 to 1:2.9:1.6 5-day Compressive Strength (psi) (PTM Nos. 604 & 611) (3) 3,000 3,000 28-day Compressive Strength (psi) (PTM Nos. 604 & 611) (3) 3,500 3,500

sample on the deck in a suitable container and do not disturb for five minutes. Then, remix the sample and perform the slump test according to AASHTO T 119.

produce good workability, but because of gradation changes, the ratios may be adjusted within limits by the Representative.

hours), and air cure as specified in Section 1042.3(d) Table A.

Accelerated Latex Modified Concrete Mix Design Requirements Cement Type I, IP, or II, Section 701.1 or other rapid setting cement accepted by the DMM/DME 3 Hour Minimum Compressive Strength 3,000 psi 12 Hour Minimum Compressive Strength 3,000 psi

mix design and ensure that the mix provides sufficient time of workability to satisfactorily finish and texture the surface. Re- verify compatibility whenever there is a change in mix components. Provide a technical expert from the latex admixture manufacturer for the design process, if directed.

1042.3CONSTRUCTION—

of the latex wearing surface before start of wearing-surface work. Include equipment specifications in the QC Plan specified in Section 1042.3(c).

1.a Abrasive Blasting or Water Blasting Equipment. Capable of removing partially loosened chips of concrete and removing rust and corrosion from reinforcement bars. Provide w ater blasting equipment with a minimum rated capacity of 5,000 pounds per square inch.

1.b Power-Driven Hand Tools. Section 1040.3(b)

1.c Scarification. Section 1041.

1.d Hydrodemolition. Section 1039.

continuous mixing, with the capacity to deliver a minimum of 6 cubic yards of latex per hour, and subject to the following:

2.a Mixing Equipment. Provide equipment with a metal plate or plates permanently attached in a prominent place, plainly marked with the gross volume of the unit in terms of mixed mortar, operating speed, auger mixing angle, and the weight -calibrated cement constant of the machi ne, in terms of a revolution counter or other output indicator, all as rated by the manufacturer.

2.b Compartments. Provide separate compartments to carry the necessary ingredients needed for the production of latex modified mortar or concrete. Cover aggregate bins at all times. Provide cement bins free of moisture and contamination at all times. Provide suitable means to carry water and additives on the truck and to incorporate the additives with the mixing water in the mix.

2.c Feed Systems. Provide a unit with a feeder system mounted under the compartment bins to deliver the ingredients to the mixing unit. Provide each bin with an accurately controlled, individual gate to form an orifice for volumetrically measuring the material drawn from each respective bin compartment. Maintain belt feeders and scrapers to prevent leakage of materials onto the deck. Set the cement bin feeding mechanism to discharge continuously, and at a uniform rate, a given volumetric weight equivalent to cement during the mixing operation. Coordinate the aggregate feeding

mechanisms with the cement feeding mechanisms to deliver the required proportions.

2.d Mixing Unit. Provide an auger-type mixing unit, incorporated into the truck's discharge chute or other suitable mixing mechanism, capable of producing latex of uniform consistency and discharging the mix without segregation.

2.e Dials and Measuring Devices. Equip the unit with an accurate revolution counter indicator allowing the reading of the volumetric weight equivalent to cement discharged during the mixing operation. Equip the counter with a ticket printout to record this quantity. Use aggregate dials that allow the setting of required openings for volumetric proportioning. Equip the unit with a cumulative water meter and a water flow gauge to accurately indicate the discharge rate of water by volume (gallons per minute) entering the mix. Provide an approved device on the mixing unit for the Representative to use to check the rate of flow of the latex modified admixture entering the mix along with the total amount of latex modified admixture contained in the mix . Coordinate the water and additive measuring devices with the cement and aggregate feeding mechanisms. E quip the flow meters with scales appropriate for the type and amount of material being added. Mount a tachometer on the mixing unit to indicate the drive shaft speed. Place required indicating devices in full view and near enough to be accurately read or readjusted by the operator while latex is being produced. Provide the operator with convenient access to controls.

2.f Calibration. Provide a unit constructed to allow convenient calibration of the gate openings and meters. Have the calibration conducted by the supplier of the latex in the presence of the Representative and recalibrate after every 100 cubic yards of production for each unit. Document the calibration of Form CS -4342 and keep with t he mobile mixer. Have the supplier of the latex make satisfactory arrangements with the Representative at least 7 calendar days in advance of calibration. Provide platform scales calibrated annually. Calibrate using the maximum water/cement ratio, cement, and aggregates listed on the approved mix design. Verify compatibility of components and mix workability time while performing a yield test at the conclusion of the calibration process, if directed. Conduct a recalibration if a change in source of aggregates occurs. Conduct additional calibration as directed. Have each approved unit carry a copy of the calibration certificate. In addition to calibration, perform a yield test according to AASHTO T 121, if directed. An additional check may be made using the following procedure: With the cement meter set on zero and controls set for the desired mix, activate the mixer discharging mixed material into a 1/4 cubic yard container (36 inches by 36 inches by 9 inches). When the container is level -struck full, making provision for settling the material into corners, the cement meter is required to show a discharge of 2 bags of cement for modified mortar (8 bags per cubic yard mix) or 1.75 bags of cement for modified concrete (7 bags per cubic yard mix).

2.g Mixing and Delivery Control. Proportion, measure, and batch cement and aggregates by a volumetric weight equivalent method. In operation, the entire measuring and batching mechanism is required to produce the specified proportions of each ingredient. Establish volume/weight relationships during the calibration of the measuring devices. Provide tolerances in proportioning the various ingredients as follows:

• Cement, weight % 0.0 to +4.0

• Fine Aggregate, weight % ±2.0

• Coarse Aggregate, weight % ±2.0

• Water, weight or volume % ±1.0

• Latex, weight or volume % ±2.0

During mixing, maintain the drive shaft speed as indicated by the tachometer at operating speed ± 50 rpm. Set the auger mixer angle in the range determined by the manufacturer. Do not exceed one-half hour for the interval between the continuous placement of successive batches. Equip the mixer to spray water.

2.h Loading. Charge aggregate bins no more than 6 hours before time of scheduled placement unless otherwise approved by the Representative. Ensure the aggregate is maintained in a uniform wet condition before loading. Determine the amount of free water on the aggregates at the time of loading by performing aggregate moisture tests according to AASHTO T 255 or ASTM C70. Adjust mix proportions to account for the amount of available free water. Empty bins and recharge if not utilized within 6 hours or if conditions contribute to variable moisture content of the aggregate. Stock aggregates in a manner that prevents contamination. Upon arrival at the project site, empty bins of aggregate that were charged before comin g to the current project. Empty the cement bin and latex tank unless use on a previous p roject can be verified by the Representative, or, in the presence of the Representative, obtain a sample of the liquid latex admixture and cement bei ng used in the mixture and d eliver the samples to the Representative for testing. The Representative will submit the samples to LTS for testing. Circulate and mix latex tank as recommended by the latex manufacturer.

Provide hand tools for placing and brushing-in freshly mixed latex and for distributing latex over the bridge deck surface before striking off with the mechanical finishing equipment . Use approved hand- operated vibrators and screeds to place and finish small areas of work. Do not use 2 -cycle engine vibrators or equipment on the prepared deck . Conduct final finishing operations immediately behind the finishing machines or screeds from work bridges of rigid construction, not in contact with the surface of the concrete, set on rails, and easily moved.

surface, survey existing gutter lines and breakpoints every 25 feet including each metal expansion dam along the length of the bridge deck. Not more than 7 days before the placement of the overlay, scarify the deck surface, to the depth indicated, as specified in Section 1041. When the indicated surface preparation includes scarification without hydrodemolition, perform scarification, then remove remaining unsound concrete and repair as specified in Section 1040. When the indicated surface preparation includes scarification and hydrodemolition, perform hydrodemolition after scarification to provide a rough and bondable surface and to remove unsound concrete, as specified in Section 1039. Perform Type 3 concrete bridge deck repairs after hydrodemolition, as directed and as specified in Section 1040. Before placement of the latex overlay, complete Type 3 deck repairs and Type 2 deck repairs exceeding 4 inches in depth as specified in Section 1040. Type 2 deck repairs that do not exceed 4 inches in depth can be placed concurrently with the latex overlay. Abrasive blast exposed reinforcement bars to remove rust, contaminants, and pockets of corrosion. Do not apply epoxy coating to reinforcement bars. Not more than 24 hours before placement begins, clean the entire surface including edges of previously placed lanes of latex, to remove trowel -cut surfaces and promote bond. Clean the surface thoroughly by water blasting, and air blasting using clean, oil -free compressed air to remove dust, slurry, blast media, weak or fractured concrete, petroleum stains, leaves, paint, debris, oil, or other foreign materials detrimental to achieving bond, if necessary. Protect the entire prepared deck surface against contamination by covering with clean full width polyethylene sheeting until the overlay operations are completed. Include cleaning methods in the QC Plan, as specified in Section 1042.3(c). Allow 48 hours of curing to elapse before performing scarification, hydrodemolition, or chipping on adjacent concrete within 6 feet of previously placed latex. Raise expansion dams and scuppers if indicated before placing the wearing surface.

acceptance according to Form CS-1042. Do not proceed with latex placement until the QC Plan has been accepted. Include in the QC Plan, testing and sampling frequencies and target points to initiate corrective measures. Include key personnel and relevant experience, method of operations , a sketch describing the equipment, and showing complete details of supports for the equipment.

placement meeting to review the specification, method, and sequence of placing latex, quality control testing, and method of protective measures, to control the concrete evaporation rate.

Do not treat screed rails with parting compound to facilitate their removal. Adjust screeds to finished grade before placing the wearing surface. For superelevated bridges, adjust screed guides to compensate for the curvature. Determine the finished grade by referencing the survey data obtained before surface preparation. Raise the existing grade or match existing grade, as indicated. Provide a final setting of the screeds such that a smooth riding surface is achieved. Do not lower the screed to compensate for wear on the existing deck or for over scarification or hydrodemolition. Before placing latex, perform a dry run by passing the finishing equipment over the deck area to check the clearance between the bottom of the screed and the prepared surface. Demonstrate that the fogging equipment is working properly during the dry run. Remove concrete that does not clear the screed by the minimum depth of wearing surface.

clean surface for a period of not less than one hour. Vacuum standing water in depressions, holes or areas of concrete removal . Maintain prepared deck in a damp, puddle- free condition. Use a fogger/mister to dampen visible dry spots before the latex placement. Brush/broom damp vertical surfaces with latex grout. For horizontal surfaces not prepared with hydrodemolition that will be in contact with the latex overlay, brush/broom damp horizontal surfaces with latex grout. When using latex concrete, collect and discard excess aggregate. Do not over -extract grout from the mix to the point that the grout becomes diluted. If directed, apply a second brushed/broomed coat of grout to areas where grout is diluted by excessive surface moisture. Immediately remove material from the deck that is not properly mixed or proportioned, or lacks component material, and regrout the area. Ensure brushed/broomed surfaces receive a thorough, even coating of latex grout and that the rate of progress is limited so that the brushed/broomed material does not become dry before it is covered with additional material, as required for the final grade. Place and strike- off the mixture to approximately 1/4 inch above final grade. Vibrate latex in front of finishing machine. For hydrodemolitioned surfaces, s nake vibrator through latex at no more than 12- inch passes. Vibrate edges, adjacent to joint bulkheads and expansion dams, in depressions, and in areas of bridge deck repair. Fill and consolidate each Type 2 deck repair placed concurrently with the overlay before the advancement of the overlay placement operation. Finish to final grade with the approved finishing equipment. Hand-finishing with a float may be required along the edge of the placement or on small areas of repair. Edge- tooling is required at joints, metal expansion dams, curbs, and previously placed lanes. Place latex continuously and complete the finishing of each area within 15 minutes after the initial brooming. Provide finish with a closed surface, free of pock marks, ridges, tears, and other defects. Place latex at a minimum rate of 20 linear feet of deck per hour, in a longitudinal direction. When placing latex against latex that has not achieved initial set, but has formed a surface crust or film, remove the surface crust until plastic latex is exposed, place fresh latex against the exposed surface and consolidate both until homogeneous. Separate screed rails and construction bulkheads from the newly placed material by passing a pointing trowel along their inside face. Do not separate metal expansion dams from the wearing surface. Ensure that this trowel cut is made for the entire depth and length of rails after the mixture has stiffened sufficiently. Conduct operations behind the finishing machines or screeds from work bridges suspended above the wearing surface. Provide work bridges of rigid construction. Do not allow work bridges to come into contact with the surface of the latex. Perform straightedge testing, surface correction and edging while the latex is still workable as specified in Section 501.3(k)3. After the straightedge testing and surface corrections have been completed and before the latex becomes nonplastic, manually texture/tine the surface transversely as specified in Section 501.3(k)4.b if mechanical texturing is not indicated. Cure the wearing surface as soon as possible without marking the fresh latex. After the latex has hardened, test the surface again as specified in Section 501.3(o). Resound the deck if directed. When mechanical texturing is indicated, p erform as specified in Section 1001.3(k)6.f . Do not begin grooving operations until directed, the latex has reached a compressive strength of 3, 000 psi according to

PTM No.604, the grooving equipment live loads can be applied as specified in Section 1042.3(g), and until the surface tolerance has been checked and high points are removed as specified in Section 501.3(o). Provide adequate lighting, as indicated on the field operation QC Plan, for placement not completed in the daylight. Ensure lighting allows proper placement, testing, and inspection operations of the entire surface area and until curing covers are placed over the surface area.

if applicable. Do not use membrane-forming or monomolecular curing compounds:

follows: Maintain cure temperatures of 45F or greater throughout the wet and dry cure period. Do not count as a curing day, a day on which the curing temperature drops below 45F . If the curing temperature falls below 35F during the curing period, the Department will consider the work unsatisfactory, and it will be rejected. Protect the overlay using methods as specified in Section 1001.3(p)4 during cool weather and Section 1001.3(p)5 during cold weather.

period. Soak burlap for a minimum of 48 hours before placement. Re- wet burlap as needed before placement. Promptly cover the surface with a double layer of clean, wet burlap within 15 feet of strike -off from the finishing machine. Place burlap so each strip overlaps one- half its width. Minimal marking of the surface from curing covers is allowed. Maintain burlap in a fully wet condition using misting hoses, fogging machines that span the entire burlap covered surface, or other approved devices until the concrete has set sufficiently to support foot traffic. At that time, place soaker hoses on the burlap to maintain continuous saturation of burlap over the entire deck surface. At a minimum, place soaker hoses at grade breaks and high sides of superelevations to ensure continuous saturation. Secure burlap to prevent lifting or displacement due to adjacent construction operations or wind. Cure the surface according to Table A.

according to Table A. Maintain the surface of the overlay in a dry condition for the entire dry cure period. Cover the surface with waterproof coverings as required. If the overlay surface becomes wet during the dry period, extend the dry cure period to the equivalent time that the overlay surface was wet.

TABLE A Curing Times and Application of Live Load

Overlay Type Depth Water Cure (hours) Dry Cure (hours) Live Load Application Total Cure Time MIN (hours) Live Load Application Comp. Strength MIN (psi) LMM or LMC ≤ 2 inches 48 72 120 3,000 > 2 inches 48 96 144 3,000 Accelerated LMC, 3 Hour All 3 None 3 3,000 Accelerated LMC, 12 Hour All 12 None 12 3,000

temperatures are between 45F and 85F . At ambient temperatures above 80F, conduct the overlay placement at night or early morning hours . If the ambient temperature is expected to reach 80F 24 hours before the overlay placement, take steps necessary, but not limited to the following t o mitigate the mix component temperatures that are acceptable to the Representative:

• cover the latex admixture tanker and ce ment tanker with wet burlap or stati on the latex admixture tanker and cement tanker in shaded areas;

• condition aggregates with cool water, cover with light-colored tarps and/or stockpile in shaded areas;

• charge the water tank on the mobile mixer with cool water as close to the time of placement as possible, or condition with ice;

• park mobile mixes in shaded areas or cover with wet burlap before the placement.

Place latex at a plastic latex mixture temperature between 50F and 85F. Stop the placement if the Representative determines that a satisfactory surface finish is not being achieved. Install a bulkhead in case of a major delay in the placement operation resulting in the formation of a surface film. During minor delays, protect the placement from drying with several layers of wet burlap. Take adequate precautions to protect freshly placed latex from rain. Stop placement operations when it starts to rain. The Representative may order removal of latex damaged by rainfall. Do not place latex when the evaporation rate exceeds 0.06 pound per square foot per hour according to ACI 305R, Figure 2.1.5. Wind breaks, sunshades, or fogging may be used to reduce evaporation to below the maximum allowable rate. Discontinue placement when the Representative determines that flash set of the latex does not provide a suitable placement or finish. Submit redesign and corrective action plan as directed.

3.a QC Sampling and Testing of Plastic Latex. Perform testing according to the accepted QC Plan. Furnish a copy of the QC Plan to be maintained in the Department's field office. Test each 5 cubic yards of latex for plastic air content, temperature, and slump. Continue testing the load until control is established. Do not wait for the completion of the initial test before collecting subsequent samples. Perform slump tests as specified in Section 1042.2(f) and air content tests according to AASHTO T 152. Notify the Inspector when sampling and QC testing are to be performed. The Inspector will witness the sampling and QC testing. Report test results to the Inspector promptly. Coordinate and facilitate changes as needed in a timely manner. Do not incorporate latex into the work that does not conform to specification requirements. Immediately separate and remove nonconforming material from the deck surface.

3.b Acceptance Testing. Latex will be accepted on a lot -by-lot basis. Test for plastic air content according to AASHTO T 152; temperature; and compressive strength according to PTM No. 611 and PTM No. 604. Each lot will consist of 20 cubic yards or a day's placement, whichever is less. The Inspector will select acceptance samples (n=1) according to PTM No. 1 . Obtain samples of fresh latex at the point of placement under the direction and supervision of the Inspector and according to PTM No. 601. Acceptance testing of plastic concrete will be performed at a site near the point of placement, as selected by the Inspector. Latex will be tested for yield as directed. Latex not conforming to specification requirements at the point of placement will be rejected. If the results of testing the plastic latex conform to specification requirements, mold a sufficient number of acceptance cylinders for 5-day compressive strength tests. Compressive strength cylinder molds of 4-inch diameter by 8- inch height may be substituted for cylinder molds of 6- inch diameter by 12- inch height. Perform compressive testing according to PTM No. 604. The Inspector will identify the cylinders as acceptance cylinders. Field cure cylinders as specified in Section 1042.2(f). The c ompressive strength of the sample will be determined as the average of the compressive strength of two 6-inch diameter by 12 inch height individual cylinders or the average of three 4- inch diameter by 8-inch height individual cylinders according to ACI 318. The lot will be accepted when the 5-day compressive strength meets or exceeds 3,000 pounds per square inch.

3.c Bond Tests.

3.c.1 Scarified Surfaces (no hydrodemolition). When the indicated surface preparation includes scarification without hydrodemolition, perform a vertical pull bond test according to ASTM C1583 between 24 hours and 72 hours after curing is complete and the latex has attained a minimum compressive strength of 3,000 psi. Perform a minimum of one vertical pull bond test on each span or day’s placement, whichever is smaller, at a location or locations as designated. If multiple tests are taken in a span, the test result is the average of the tests for that span. The required minimum bond strength between the latex overlay and substrate is 250 psi. If the initial vertical pull bond test res ults do not meet the minimum requirement of 250 psi, perform up to three additional vertical pull bond tests per span where the minimum requirement of 250 psi was not met. After additional testing, if the average of the test results for a span do not meet the minimum requirement of 250 psi, the bond between the substrate and latex overlay in each span not meeting this requirement is considered defective work, and the latex overlay must be removed and replaced at no additional cost to the Department. Repair bond test locations with nonshrink grout, as specified in 1001.2(d).

3.c.2 Hydrodemolitioned Surfaces. When the indicated surface preparation includes hydrodemolition and the overlay exhibits cracking or surface tears and potential debonding, perform bond tests as specified in Section 1042.3(f)3.c.1 as directed.

on the latex surface until the end of the period according to Table A, and until the latex has achieved the minimum strength as specified in Section 1042.3(d), Table A.

When latex overlays exhibit cracking or surface tears , perform an investigation with the Representative to determine the type of cracking, source of crac king, and extent of cracking. Measure the width, depth , and length of each crack and establish the locations of the ends of each crack with respect to permanent reference points. Coring may be necessary if crack depths cannot be accurately determined using a mechanical probe. If coring is required, obtain two cores at each location, submit one core to an independent laboratory for analysis of the cracks and submit one core to the Representative for analysis of the cracks at the LTS. If the investigation indicates the type of cracking to be nonstructural cracks (plastic shrinkage, drying shrinkage, temperature related, or surface tears caused by finishing and texturing) that are evidence of defects in mater ials or workmanship, repair surface cracks and tears greater than 1/4 -inch depth and between 0.007 inch and 0.016 inch width at no additional cost to the Department. Use HMWM penetrating crack filler/sealer to repair the surface cracks and tears. Submit for review, a detailed Quality Control and Action Plan that includes, at a minimum, the proposed crack sealing material data sheet from the manufacturer and conditions for use, including ambient and substrate temperature and moisture conditions. Do not perform crack sealing before the Quality Control and Action Plan has been reviewed by the Representative. Keep cracks clean, covered, and dry until the crack sealing operation is performed to the satisfaction of the Representative. Unless directed in writing by the District Executive, remove and replace wearing surface deficient in surface tolerance as specified in Section 501.3(o); defective in air content as specified in Section 1042.2(f); defective in compressive strength as specified in Section 1042.3(f)3.b; failing to bond to the substrate; bonded to unsound concrete; exhibiting nonstructural cracks or tears greater than 1/4 inch depth and greater than 0.016 inch width; or showing surface defects resulting from the effects of rain, improper finish, improper cure, or honeycombing, which, in the Representative's opinion, cannot be repaired.

longitudinal or transverse construction joints. Seal construction joints as shown on the Standard Drawings.

1042.4MEASUREMENT AND PAYMENT—

As indicated, for the type specified, for the item indicated. Survey before surface preparation and bond tests are incidental to this item. The Department will pay for grade adjustments of expansion dams and scuppers, scarification, and hydrodemolition separately. When hydrodemolition is not indicated, the Department will pay for bridge deck repairs separately under the respective type of concrete bridge deck repair items. When hydrodemolition is indicated, the Department will pay for Type 3 deck repairs and Type 2 deck repairs exceeding 4 inches placed and cured before the overlay placement. Construction joint sealing with HMWM is incidental to the Latex Modified Mortar or Concrete Wearing Surface.

The limits of payment are the peaks of the roughened deck surface elevation to the bottom of the Latex Modified Concrete Wearing Surface. For material costs only for furnishing latex modified mortar or concrete to the work site. Labor and equipment costs to place the material are incidental to the Latex Modified Concrete Wearing Surface work.