Rev. 8-14-97 MICRO-SURFACING DESCRIPTION. This work shall consist of a mixture of polymer modified asphalt emulsion, mineral aggregate, mineral filler, water, and other additives to fill ruts or provide a wearing course for existing pavements in accordance with section 105.03. The mixture shall be capable of filling up to 40 mm (1 1/2 inch) wheel ruts in one pass, be capable of field regulation of the setting time, and be suitable for nighttime placement. The mixture shall be capable of being spread in variable thick cross sections which, after curing and initial traffic consolidation, resist compaction throughout the entire design tolerance of bitumen content and variable thickness to be encountered. MATERIALS. Materials shall be as follows: (a) Polymer Modified Asphalt Emulsion. The emulsified asphalt shall be a quick-set, polymer modified CSS-1h emulsion conforming to the requirements specified in AASHTO M 208 except the cement mixing test shall be waived. The polymer material shall be milled or blended into the asphalt or shall be blended into the emulsifier solution prior to the emulsification process. The minimum polymer solids content will be 3.0% based on the residual of the emulsion. Post addition of polymer to the emulsion will not be permitted. Additional requirements shall be as follows:
Each load of emulsified asphalt shall be accompanied by a type A certification, in accordance with 916, from the asphalt emulsion manufacturer to assure that it is the same formulation used in the Job Mix Formula (JMF) unless changes have been approved by the Engineer. In addition the certificate shall certify that the polymer content of the emulsion is greater than 3.0 percent polymer solids based on the residue of the emulsion. (b) AGGREGATE. The aggregate for rut fill or leveling courses shall be crushed stone, crushed dolomite, sandstone, air-cooled blast furnace slag or crushed gravel in accordance with the physical properties of 904 except percent of fractured particles shall be a minimum of 95. The gradation for the rut fill course shall meet the type B gradation in Table A. The gradation for the leveling course shall meet the type A gradation in Table A. The aggregate for surface courses shall be in accordance with 904.02(d). The gradation shall meet the type A gradation in Table A. Table A
(c) MINERAL FILLER. The mineral filler shall be portland cement meeting the requirements of AASHTO M 85, Type I. (d) WATER. The water shall be in accordance with 913.01 and shall be free from harmful soluble salts. (e) ADDITIVE. Mix set additives shall be added as required to provide control of the quick-set properties. JOB MIX FORMULA AND PROPORTIONING. The manufacturer of the polymer modified emulsion shall submit a mix design and JMF for the specific materials to be used on the project. The mix design shall meet the following requirements and specified properties of the International Slurry Seal Association (ISSA) tests:
The JMF shall state the following (all percentages are based on the dry weight of the aggregate):
WEATHER LIMITATIONS. The mixture shall only be applied when it is not raining, the existing pavement surface temperature is a minimum of 7EC (45EF) and rising and there is no forecast of an atmospheric temperature below 0EC (32EF) within 24 h from the time the mixture is applied. Applications after October 31 and before April 1 shall not be made when the existing pavement surface temperature is less than 10EC (50EF). MIXING EQUIPMENT. The micro-surfacing mixture shall be produced in a self-propelled, front feed, continuous loading, mixing machine equipped with a chain-dragged conveyer belt aggregate delivery system and an inter-connected positive displacement, water-jacketed gear pump to accurately proportion aggregate and asphalt emulsion. The mineral filler feed shall be located so the proper amount of mineral filler is dropped on the aggregate before discharge into the pugmill. A spray bar shall be provided to completely pre-wet the aggregate dropping down to the pugmill with additive and water prior to introduction of asphalt emulsion. The twin-shaft, multi-blade pugmill shall be a continuous flow type and a minimum of 1250 mm (50 inches) long. The blade size and side clearances shall meet the equipment manufacturer's recommendations. The emulsion shall be introduced within the first one-third of the mixer length to ensure proper mixing of all materials prior to exit from the pugmill. The machine shall be equipped with opposite side driving stations to allow full control of the machine from either side. The mixer will be equipped with a remote forward speed control at the back mixing platform so the back operator can control forward speed and level of mixture in the paving or rut box. The Contractor shall provide material control devices that are readily accessible and positioned so the amount of each material used can be determined at any time. The mixing machine shall be equipped with a water pressure system and nozzle type spray bar to provide a water spray ahead of and outside the spreader box when required. Water shall be applied at a rate to dampen the surface, but shall not create free flowing water ahead of the spreader box. Truck mounted machines with a position, non-slipping aggregate delivery system and without the front feed, continuous loading feature may be used on project segments of less than 12,600 m5 (15,000 square yards) or on spot repairs. EQUIPMENT CALIBRATION. Each mixing unit to be used on the project shall be calibrated for each type of application in the presence of the Engineer prior to construction. The Contractor shall generate documentation for the Engineer. The documentation shall include individual calibrations of each material at various settings, which relate to the machine's metering devices. No machine shall be allowed to work on the project until the calibration has been completed and/or accepted. Any change in aggregate or emulsion source shall require re-calibration. At the conclusion of the calibration of each machine to be used on the job, the Contractor shall demonstrate the machine's ability to mix all components together so as to simulate an end product. SPREADING EQUIPMENT. The paving mixture shall be spread uniformly by means of a mechanical type spreader box, attached to the mixer and equipped with paddles mounted on adjustable shafts to continually agitate and distribute the materials. The equipment shall provide sufficient agitation to prevent the mix from stagnating, breaking in the box or causing excessive side build-up or lumps. To prevent loss of the mixture from the box, the Contractor shall attach flexible seals, front and rear, in contact with the road. On single courses and finish courses a secondary strike off shall be attached to the spreader box to provide a finished surface texture. Rut filling applications shall be accomplished one pass per rut with a steel V-configuration screed rut box specifically designed for rut filling applications. The rut box shall spread the mixture at a width of 1.5 to 1.8 m (5 to 6 feet) and be capable of feathering the edges and providing the proper crown or overfill. The overfill shall be determined by averaging the rut depth over a specific area, lane, or lot. The overfill shall be at a depth of 5 mm (3/16 in.) overfill per 25 mm (1 in.) of rut depth. SURFACE PREPARATION. Prior to applying mixture, the surface shall be cleaned by removing vegetation, loose materials, dirt, mud, and other objectionable materials. Water shall be misted onto the existing pavement surface immediately prior to applying the asphalt mixture. Tack coat in accordance with 406 will be required on portland cement concrete surfaces. The tack coat application rate shall be 0.23 L/m5 (0.05 gal./syd). TEST STRIP. The Contractor shall construct a test strip to be evaluated by the Engineer. This test strip shall be 300 m (1,000 feet) long and consist of all of the application courses specified. The test strip shall be constructed at the same time of day or night the full production shall be applied and may be constructed in two days or nights when multiple course applications are specified. The Engineer will evaluate the completed test strip after 24 h of traffic to determine if the mix design is acceptable. Full production may begin after the Engineer accepts a test strip. The construction of the test strip will be paid for at the individual bid price for the courses constructed. APPLICATION. The paving mixture shall be spread to fill minor cracks and shallow potholes and leave a uniform surface. When rut filling, the designed profile of the pavement cross section shall be restored. Excess crowning, or overfilling, of rut areas shall be avoided. Squeegees and lutes shall be used to spread the mixture in areas inaccessible to the spreader box and in areas requiring hand spreading. A sufficient amount of material shall be carried at all times in all parts of the spreader box to ensure complete coverage. No lumps or unmixed aggregate will be permitted in the finished surface. Adjustments to the additive will be permitted to provide a slower setting time when hand spreading is required. If hand spreading is necessary, the mixture shall be poured in a small windrow along one edge of the surface to be covered and then spread uniformly by means of a hand squeegee or lute. A smooth, neat seam shall be provided where 2 passes meet. Excess material shall be immediately removed from the ends of each run. OPENING TO TRAFFIC. The latex modifier shall be capable of producing an emulsified asphalt paving mixture that cures at a rate which shall permit traffic on the pavement within one hour after application without damaging the pavement surface. QUALITY CONTROL. The Contractor shall produce a mixture that will be in compliance with the job mix formula. Verification shall be in accordance with the following procedures which are required at a frequency of one test per 450 Mg (500 tons) of mixture placed or a minimum of one per day. The gradation of the aggregate shall be determined from samples obtained from the aggregate stockpile. The amount of mineral filler added to the mixture shall be included in determining the total passing the 75 :m (No. 200) sieve. The asphalt content of the mixture shall be determined from the equipment's counter readings. The spread rate shall be verified by means of meter readings of the material control devices. Results from all tests and equipment meter readings shall be given to the Engineer by the completion of the days production. ACCEPTANCE. During paving, in the presence of the Engineer, the mixture shall be sampled twice daily, or as directed, from the pugmill discharge chute. A non-absorptive container, such as a loafpan, of sufficient size shall be used to obtain a sample from the entire cross-section for the mixture being discharged. The samples will be tested by the Engineer for compliance with the residual asphalt content and gradation. The residual asphalt content shall be within "0.7 percent of the residual asphalt content on the JMF. The gradation shall be within the applicable gradation limits in Table A. METHOD OF MEASUREMENT. The quantity for a leveling or surface course of micro-surfacing, completed and accepted in place, will be paid by the square meter (square yard). The width of the pavement course will be the width that is placed. The length will be measured along the center line of each roadway or ramp. The quantity for a rut fill course of micro-surfacing, completed and accepted in place, will be measured by the mass (weight) of the dry aggregate used, measured by the megagrams (ton). The mass (weight) will be based on the machine calibration. BASIS OF PAYMENT. The cost of furnishing materials, equipment, labor, and tack coat, if required, and all incidentals will be included in the cost of this work. Payment for accepted quantities, complete in place, will be made at the contract unit price for:
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