Modified Concrete Suppliers, LLC

LMC Installation | LMC Specifications

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

Description

This work shall consist of constructing a Latex Modified Concrete (LMC) bridge deck overlay using hydrodemolition 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

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 DOW Reichhold Mod A – FHWA -RD-78-35
Fine Aggregate - Natural Concrete Sand - ASTM C-33
Coarse Aggregate - Washed Size 7, 8, 9m, 11 or CA13 - ASTM C-33
Water - potable - ASTM C-685

Proportioning

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:

Type I Portland Cement - 94 lbs.
Latex Admixture - 3.5 gals.
Natural Concrete Sand - 210 to 255 lbs. (50-60% fine aggregate by total wt.)
Coarse Aggregate - 208 to 168 lbs.
Water - 0 gal. to 2.9 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

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.

Mixer

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 especially 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 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.

Calibration

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.

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 he 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.

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					LMC Installation \| LMC Specifications Specification for latex (polymer) modified concrete bridge deck overlay for new and existing bridges using hydrodemolition Description This work shall consist of constructing a Latex Modified Concrete (LMC) bridge deck overlay using hydrodemolition 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 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 DOW Reichhold Mod A – FHWA -RD-78-35 Fine Aggregate - Natural Concrete Sand - ASTM C-33 Coarse Aggregate - Washed Size 7, 8, 9m, 11 or CA13 - ASTM C-33 Water - potable - ASTM C-685 Proportioning 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: Type I Portland Cement - 94 lbs. Latex Admixture - 3.5 gals. Natural Concrete Sand - 210 to 255 lbs. (50-60% fine aggregate by total wt.) Coarse Aggregate - 208 to 168 lbs. Water - 0 gal. to 2.9 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 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. Mixer 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 especially 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 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. Calibration 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. 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 he 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. Next Page >