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1.00 ASPHALT RUBBER CAPE SEAL Asphalt rubber cape seal shall consist of an application of an asphalt rubber seal coat followed by an application of a slurry seal coat. Asphalt rubber cape seal shall conform to the requirements specified in these special provisions. 1.01 Asphalt Rubber Seal Coat Asphalt rubber seal coat shall consist of an application of asphalt rubber binder and screenings precoated with paving asphalt. Asphalt rubber seal coat shall conform to the requirements specified for seal coats in Section 37-1, “Seal Coats”, of the Caltrans Standard Specifications and to these special provisions. 1.02 Materials A Certificate of Compliance shall be furnished to the engineer in accordance with section 6 - 1.07, “Certificates of Compliance”, of the Caltrans Standard Specifications for each material used in asphalt rubber binder and the asphalt rubber binder mixture. It shall certify that the material conforms to the requirements in these special provisions. When requested by the engineer, the contractor shall also submit samples with the certificates of compliance. The contractor shall provide the engineer with a Material Safety Data Sheet (MSDS) for each of the constituent components of the asphalt rubber binder and for the completed mixture of the asphalt rubber binder and for the completed mixture of the asphalt rubber binder. Crumb rubber modifier (CRM) shall be tested, except for the grading requirement, at least once for every 250 tons with a minimum of once per project. CRM shall be tested for grading every truckload delivered to the project. Paving asphalt shall be tested at least once for every 200 tons of production with a minimum of once per project. Asphalt modifier shall be tested at least once for every 25 tons of production with a minimum of once per project. A copy of the laboratory test results for the test parameters specified in these special provisions for CRM, paving asphalt and asphalt modifier shall be submitted to the engineer with the certificate of compliance for each truck load of individual material delivered to the project. Certified volume or weight slips shall be delivered to the engineer for all materials supplied. Paving asphalt to be used in the asphalt rubber binder shall be grade AR-4000 and shall conform to Section 92, “Asphalts”, of the Caltrans Standard Specifications and these special provisions. The paving asphalt for use in asphalt rubber shall be modified with an asphalt modifier. The asphalt modifier will be resinous, high flash point, aromatic hydrocarbon compound and shall conform to the following requirements:
The asphalt modifier shall be proportionately added to the paving asphalt at he production site where the asphalt rubber binder is blended and reacted. Asphalt modifier shall be added at an amount of 2.5 to 6.0 percent by weight of the paving asphalt based on the recommendation of the asphalt rubber binder supplier. The paving asphalt shall be at a temperature of not less than 375 F. nor more than 440 F. when the asphalt modifier is added. If the asphalt modifier is combined with the paving asphalt, before being blended with the CRM, the combined paving asphalt and asphalt modifier shall be mixed by circulation for a period of not less than 20 minutes. This premixing of asphalt modifier and the paving asphalt will not be required when all ingredients of the asphalt rubber binder are proportioned and mixed simultaneously. Asphalt modifier and paving asphalt shall be measured for proportioning. The CRM shall consist of a combination of scrap tire CRM and high natural CRM. The scrap tire CRM shall consist of ground granulated rubber derived from any combination of automobile tires, truck tires or tire buffings. The high natural CRM shall consist of ground or granulated rubber derived from materials that utilize high natural rubber sources. Steel and fiber separation may be accomplished by any method. Cryogenic separation, if utilized, shall be performed separately from and prior to grinding or granulating. All CRM shall be ground or granulated at ambient temperature. Cryogenically produced CRM particles which can pass through the grinder or granulator without being ground or granulated respectively, shall not be used. CRM shall not contain more than 0.01 percent wire (by weight of CRM) and shall be free of all other contaminants, except for fabric. Fabric shall not exceed 0.05 percent by weight of CRM. The test and method for determining the percent by weight of wire and fabric is available at the Caltrans Transportation Laboratory, Pavement Branch, Sacramento , California , Telephone (916) 227-7300 and will be furnished to interested persons upon request. A certificate of compliance certifying these percentages shall be furnished to the engineer in accordance with section 6-1.07, “Certificates of Compliance,” of the Caltrans Standard Specifications. The length of any individual particle shall not exceed 3/16 inch. The CRM shall be sufficiently dry so as to be free flowing and not to produce foaming when combined with the blended paving asphalt and asphalt modifier mixture. Calcium carbonate or talc may be added at a maximum of 3 percent by weight of CRM to prevent CRM particles from sticking together. The CRM shall have a specific gravity between 1.1 and 1.2 as determined by California Test 208. Scrap tire CRM and high natural CRM, shall be delivered to the production site in separate bags and shall be sampled and tested separately. CRM material shall conform to the following requirements as determined by ASTM Designation D 297:
The CRM for asphalt rubber binder shall conform to the gradations specified below when tested in accordance with ASTM Designation: C 136 amended as follows: Split or quarter 100 grams +/- 5 grams from the CRM sample and dry to a constant weight at a temperature of not less than 135 F nor more than 145 F and record the dry sample weight. Place the CRM sample and 5.0 grams of talc in a one pint jar, then shake it by hand for a minimum of one minute to mix the CRM and the talc. Continue shaking or open the jar and stir until the particle agglomerates and clumps are broken and the talc is uniformly mixed. Place one rubber ball on each sieve. Each ball shall have a weight of 8.5 +/- 0.5 grams, have a diameter of 24.5 +/- mm, and shall have a Shore Durometer “A” hardness of 50 +/- 5 per ASTM Designation D 2240. After sieving the combined material for 10 minutes +/- 1, disassemble the sieves. Any material adhering to the bottom of a sieve shall be brushed into the next finer sieve. Weigh and record the weight of the material retained on the No. 8 sieve and leave this material (do not discard) on the scale or balance. Any observed fabric balls shall reaming on the scale or balance and shall be placed together on the side of the scale or balance to prevent the fabric balls from being covered or disturbed when placing the material from finer sieves on to the scale or balance. The material retained on the next finer sieve (No. 10 sieve) shall be added to the scale or balance. Weigh and record that weight as the accumulative weight retained on that sieve (No. 10 sieve). Continue weighing and recording the accumulated weights retained on the remaining sieves until the accumulated weight retained in the pan has been determined. Prior to discarding the CRM sample, separately weigh and record the total weight of the fabric balls in the sample. Determine the weight of material passing the No. 200 sieve (or weight retained in the pan) by subtracting the accumulated weight retained on the No. 200 sieve from the accumulated retained weight in the pan. If the material passing the No. 200 sieve (or weight retained in the pan) has a weight of 5 grams or less, cross out the recorded number for the accumulated weight retained in the pan and copy the number recorded for the accumulated weight retained on the No. 200 sieve and record that number (next to the crossed out number) as the accumulated weight retained in the pan. If the material passing the No. 200 sieve (or weight retained in the pan) has a weight greater than 5 grams, cross out the recorded number for the accumulated weight retained in the pan, subtract 5 grams from that number and record the difference next to the crossed out number. The adjustment to the accumulated with retained in the pan is made to account for the 5 grams of the talc added to the sample. For calculation purposes, the adjusted accumulated weight is the same as the adjusted accumulated weight retained in the pan. Determine the percent passing based on the adjusted total sample weight and recorded to the nearest 0.1 percent.
1.03 Asphalt Rubber Binder The asphalt rubber binder shall consist of a mixture of paving asphalt, asphalt modifier and crumb rubber modifier. At least two weeks before its intended use, the contractor shall furnish to the engineer 4 one quart cans filled with the asphalt rubber binder proposed for use on the project. The contractor shall supply to the engineer for approval a binder formulation and samples of all materials to be used in the asphalt binder, at least two weeks before construction is to begin. The binder formulations shall consist of the following information: PAVING AND ASPHALT MODIFIERS
CRUMB RUBBER MODIFIER
ASPHALT RUBBER BINDER
The method and equipment for combining the paving asphalt, asphalt modifier and CRM shall be so designed and accessible that the engineer can readily determine the percentages by weight for each material being incorporated into the mixture. The proportions of the materials, by total weight of the asphalt rubber binder shall be 80 percent +/- 2 percent combined paving asphalt and asphalt modifier, and 20 percent +/- 2 percent CRM. However, the minimum amount of CRM shall not be less than 18.0 percent. Lower values which are rounded up shall not be allowed. The CRM shall be combined at the production site and shall contain 75 percent +/-2 percent scrap tire CRM and 25 percent +/- 2 percent high natural CRM, by weight. The paving asphalt and asphalt modifier shall be combined into a blended mixture that is chemically compatible with the crumb rubber modifier to be used. The blended mixture is considered to be chemically compatible when it meets the requirements for asphalt rubber binder (after reacting) found elsewhere in these special provisions. The blended paving asphalt and asphalt modifier mixture, and the CRM shall be combined and mixed together at the production site in a blender unit to produce a homogenous mixture. The temperature of the blended paving asphalt and asphalt modifier mixture shall not be less than 375 F nor more than 440 F when the CRM is added. The combined materials shall be reacted for a minimum of 45 minutes after incorporation of all the CRM at a temperature of a not less than 375 F nor more than 425 F. The temperature shall not be higher than 10 F below the actual flash point of the asphalt rubber binder. After reacting, the blended asphalt rubber binder shall conform to the following requirements:
The reacted asphalt rubber binder shall be maintained at a temperature of not less than 375 F nor more than 425 F. If any of the material in a batch of asphalt rubber binder is not used within four hours after the 45 minute reaction period, heating of the material shall be discontinued. Any time the asphalt rubber binder cools below 375 F and is then reheated, it shall be considered a reheat cycle. The total number of reheat cycles shall not exceed 2. The material shall be uniformly reheated to a temperature of not less than 375 F nor more than 425 F prior to use. Additional scrap; tire CRM may be added to the reheated binder and reacted for a minimum of 45 minutes. The cumulative amount of additional scrap tire CRM shall not exceed 10 percent of the total binder weight. Reheated asphalt rubber binder shall conform to the requirements for blended asphalt rubber. 1.04 Screenings The screenings shall conform to the requirements in these special provisions and section 37-1.02, “Materials”, of the Caltrans Standard Specifications, except that the third, fourth, eighth and ninth paragraphs of section 37-1.02 shall not apply. Stockpiling of screenings after preheating and precoating with paving asphalt will not be permitted. Canvas or similar covers that completely cover each load of precoated screenings shall be used during hauling to minimize temperature drop of the precoated screenings. The screenings grading shall conform to the following requirements prior to precoating with paving asphalt:
Screenings shall conform to the following quality requirements immediately prior to preheating:
Screenings for asphalt rubber seal coat shall be preheated between 260 F and 325F uniformly coated at a rate of 0.5 to 1 percent of grade AR-4000 paving asphalt by weight of dry aggregate at a central mixing plant. The coating will be determined upon a visual inspection of the first initial load and thereafter as deemed necessary. 1.05 Equipment The contractor shall utilize the following equipment for asphalt rubber seal coat operations:
All equipment shall be approved by the engineer prior to use. 1.06 Applying Asphalt Rubber Binder Asphalt rubber binder shall be applied in accordance with the requirements specified for applying asphaltic emulsion in these special provisions and in section 37-1.05, “Applying Asphaltic Emulsion.” of the Caltrans Standard Specifications, except that the second, third, forth, fifth, ninth and twelfth paragraphs of section 37-1.05 shall not apply. Asphalt rubber binder for asphalt rubber seal coat shall be applied where not shown on the plans at the rate of 0.55 - 0.65 gallons per square yard. The exact rate will be determined by the engineer. Asphalt rubber binder shall be placed upon a clean, dry surface. The pavement surface temperature shall be a minimum of 50 F where asphalt rubber binder is to be applied. The atmospheric temperature shall be a minimum of 50 F and a maximum of 105 F. Distributor bar height, distribution speed and shielding materials shall be utilized to reduce the effects of wind upon spray distribution as directed by the engineer. The engineer shall delay or reschedule work when high gusting or dirty winds prevent or adversely affect binder or screening application operations. All necessary equipment shall be in position and ready to commence placement operations before starting. The contractor shall comply with all Federal, State, and Local environmental laws, rules, regulations and ordinances including but not limited to air quality requirements. The asphalt rubber binder shall be applied to the roadway immediately following mixing and reacting and shall be applied at a temperature of not less than 385 F nor more than 415 F. Asphalt rubber binder applications shall not be in excess of that which can be covered with screenings within four minutes. When placing asphalt rubber seal coat at intersections, turn pockets, gore points and other irregular areas, asphalt rubber application shall not be in excess of that which can be covered with screenings within 15 minutes. When joining edges against areas with screenings, the joint shall be swept clean of excess screenings prior to the adjacent application of asphalt rubber binder. Transverse joints of this type shall be constructed by placing roofing paper across an over the edge of the previous asphalt rubber seal coat application. Once the spraying has progressed beyond the paper, the paper shall be removed immediately. The longitudinal joint between adjacent applications of screenings shall coincide with the line between designated traffic lanes. All longitudinal joints shall be overlapped for complete coverage. The overlap shall not exceed four inches. At longitudinal joints with screenings, the edge shall be broomed back and blended to eliminate any difference in elevation. They shall be free from ridges and depressions and have a uniform appearance consistent with the adjacent sealed surface. All defects shall be corrected at the contractor's expense. Joints between areas of asphalt rubber binder without screenings shall be made by overlapping asphalt rubber binder distributions. The excess material shall be properly dispersed by spreading with a squeegee or rake over a larger area of freshly applied asphalt rubber binder. The application of asphalt rubber binder to areas not accessible with the distributor bar on the distributor truck shall be accomplished by using pressurized hand wands or other means approved by the engineer. 1.07 Spreading Screenings Screenings for asphalt rubber seal coat shall be spread in accordance with the requirements specified for spreading screenings on Asphaltic emulsion in these special provisions and in section 37-1.06, “Spreading Screenings”, of the Caltrans Standard Specifications, except the first, fifth, sixth and seventh paragraphs of section 37-1.06 shall not apply. Following the application of the asphalt rubber binder, screenings shall be placed on all areas receiving asphalt rubber binder. Screenings for asphalt rubber seal coat shall be applied at a temperature of not less that 225 F and not more than 325 F after applying the asphalt rubber binder. The contractor shall prevent any vehicle, including construction equipment, from driving on the asphalt rubber binder prior to the application of screenings. Screenings shall be applied at a rate of 23-40 pounds per square yard. The exact rate will be determined by the engineer. The completed spread rate shall be within 10 percent of the rate determined by the engineer. The completed surface shall be free of gaps, ridges, depressions, or other irregularities caused by the application of the asphalt rubber seal coat. 1.08 Finishing Asphalt rubber seal coat shall be finished in accordance with the requirements for finishing screenings spread on asphaltic emulsion in these special provisions and in section 37-1.07, “Finishing”, of the Caltrans Standard Specifications, except that the second, third, seventh, eighth and ninth paragraphs of section 37-1.07 shall not apply. Initial rolling of the asphalt rubber seal coat shall consist of a minimum of one complete coverage with one or more pneumatic tired rollers and shall begin within 90 seconds after the placement of screenings. The distance between the rollers and the screenings spreader shall not exceed 200 feet at any time during the spreading of the screenings operations. A minimum of three complete coverage as defined in section 39-6.03, “Compacting”, of the Caltrans Standard Specifications with pneumatic tired rollers, after the initial coverage, shall be made on the asphalt rubber seal coat. At the contractor's option, (if approved by the engineer) the final roller coverage may be made with a steel wheeled roller weighing between 8 and 10 tons. If a steel wheeled roller is used it shall be operated in the static mode only. Sweeping shall be a multi-step operation following final rolling of the screenings. Loose screenings shall be removed from the roadway surface and abutting adjacent areas. Loose screenings shall be disposed of at least 150 feet from the nearest waterway and areas shall be provided and identified for this purpose. Removal of excess screenings shall be completed before uncontrolled traffic is permitted on the completed asphalt rubber seal coat. Final sweeping shall be done and all loose screenings shall be removed without dislodging the screenings set in the asphalt rubber binder prior to acceptance. Pilot cars shall be sufficiently available to continuously convoy and control traffic. Pilot cars used to convoy or otherwise control traffic shall have radio contact with each other and other personnel in the work area. Pilot cars shall use only traffic lanes open to public traffic. 1.09 Measurement and Payment Quantities of asphalt rubber binder for asphalt rubber seal coat will be measured in the same manner specified for asphalt in Section 92-1.05, “Measurement,” of the Caltrans Standard Specifications. Quantities of screenings for asphalt rubber seal coat to be paid for by the ton will be determined after preheating and precoating with paving asphalt in the same manner specified for asphalt concrete in Section 39-8.01, “Measurement,” of the Caltrans Standard Specifications. The contract price paid per ton for asphalt rubber binder shall include full compensation for furnishing all labor, materials, tools, equipment and incidentals and for doing all the work involved in the furnishing and applying asphalt rubber binder, complete in place, as shown on the plans, as specified in these special provisions and as directed by the Engineer. The contract price paid per ton for screenings (hot-applied) shall include full compensation for furnishing all labor, materials (including paving asphalt for precoating screenings), tools, equipment and incidentals and for doing all the work involved in the furnishing and applying screenings, complete in place, including preparation for seal coat and preheating and precoating screenings, as shown on the plans, as specified in these special provisions and as directed by the Engineer. Full compensation for furnishing, placing, maintaining, and removing C6 and W6 signs and temporary supports or barricades for the signs required for the application of asphalt rubber seal coat, as shown on the plans, as specified in these special provisions and as directed by the Engineer shall be considered as included in the contract price paid for the items. 1.10 Flush Coat This work shall consist of an application of fog seal coat and sand cover to the surface of asphalt rubber seal coat when required by the Engineer or as shown on the plans, and in accordance with the provisions in section 37-1 “Seal Coats”, of the Caltrans Standard Specifications and these special provisions. If required by the Engineer a flush coat shall be applied to the asphalt seal coat immediately after removal of excess screenings following initial brooming of the asphalt rubber seal coat and prior to opening the lane to uncontrolled public traffic, as directed by the engineer. Attention is directed to asphalt rubber seal coat elsewhere in these special provisions regarding finishing of asphalt rubber seal coat and flush coat. 1.11 Fog Seal Coat Attention is directed to “Order Of Work” of these special provisions regarding application of asphaltic emulsion (fog seal coat). Asphaltic emulsion shall be grade CSS1, CSS1H or CQS1h, unless otherwise directed by the engineer. The application rate of the fog seal (asphaltic emulsion and added water) shall be such that the original asphaltic emulsion will be spread at a rate of 0.03 to 0.06 gallons per square yard. The exact rate of application will be determined by the engineer. Attention is directed to section 7-1.11, “Preservation of Property”, of the Caltrans Standard Specifications and “Existing Highway Facilities” of these special provisions regarding protecting the highway facilities from the fog seal coat. During fog seal coat operations the surface upon which a seal coat is being applied shall be closed to public traffic. Care shall be taken to avoid tracking fog seal coat material onto existing pavement surfaces beyond the limits of construction. 1.12 Sand Cover Sand for sand cover shall conform to the fine aggregate grading requirements in section 90-3.03, “Fine Aggregate Grading”, of the Caltrans Standard Specifications and these special provisions. Sand shall be free from any clay or organic material. Sand shall be spread by means of a self propelled chip spreader equipped with a computerized device that will spread the sand at a uniform rate over the full width of a traffic lane in a single application. Sand shall be spread at a rate of 2 to 4 pounds per square yard. The exact rate will be determined by the engineer. If approved by the engineer other equipment may be used to spread the sand. Sand cover shall be applied immediately following application of the fog seal. 1.13 Measurement and Payment Sand cover will be measured in the same manner specified for screenings in Sections 37-1.08, “Measurement,” and 37-109, “Payment” of the Caltrans Standard Specifications. Full compensation for furnishing, placing, maintaining, and removing C6 and W6 signs and temporary supports or barricades for the signs required for the application of the flush coat, as shown on the plans, as specified in these special provisions and as directed by the Engineer shall be considered as included in the contract price paid for the items of work involved and no additional compensation will be allowed therefor. No adjustment in compensation will be made for any increase or decrease in the quantity of asphaltic emulsion (fog seal coat) required, regardless of the reason for such increase or decrease. The provisions in Section 4-1.03B, “Increased or Decreased Quantities,” shall not apply to the item of asphaltic emulsion (fog seal coat). 2.0 SLURRY SEAL 2.01 Scope and Purpose Slurry Seal shall consist of mixing asphalt emulsion, aggregate, and water and spreading the mixture on a surface or pavement where shown on the plans, as specified in these specifications and the special provisions, and as directed by the Engineer. Latex modified slurry seal is used in the same applications as a standard slurry seal however latex slurry seal has higher binder cohesion that leads to improvements in resistance to raveling, especially in cul-de-sacs. Latex modified slurry seals are more abrasion resistant and can be laid at higher application rates without bleeding or deformation . The asphalt rubber seal coat shall be opened to traffic for at least seven days before placing the slurry seal . 2.02 Materials The materials for slurry seal immediately prior to mixing shall conform to the following requirements: 2.02A Latex Modified Asphalt Emulsion Latex emulsified asphalt shall be a quick traffic, quick cure (QT-QC) type, shall be homogeneous and show no separation after thorough mixing, shall break and set on the aggregate within five (5) minutes and shall be ready for cross-traffic within fifteen (15) to forty five (45) minutes. The latex asphalt emulsion shall conform to the requirements in Table I.
2.02B Water Water shall be potable, free of harmful soluble salts and shall be of such quality that the asphalt will not separate from the emulsion before the slurry seal is in place in the work.
2.02C Aggregate Aggregate shall consist of sound, durable, crushed stone or crushed gravel and approved mineral filler. The material shall be free from vegetable matter and other deleterious substances. Aggregates shall be 100% crushed with no rounded particles, volcanic in origin and black in color, as supplied by George Reed, Table Mountain Plant, Sonora, CA., or Equal. The use of gray or light-colored aggregate will not be allowed . The percentage composition by weight of the aggregate shall conform to the following grading:
The aggregate shall also conform to the following quality requirements:
Styrene Butadiene Rubber latex shall be added to the water/soap phase by injection prior to the mill manufacture of the asphalt emulsion by the emulsion producer. The latex shall be BASF NX 1118 or approved equal. The amount of latex solids shall be between 3 and 4 percent of the asphalt residual content and shall be certified by the emulsion producer on each load of emulsion delivered to the job site. No post or field addition of Polymer Latex will be allowed. Samples of latex shall be provided and shall conform to the following requirements.
The mineral filler shall be either Portland Cement or other approved mineral fillers, if required. Portland Cement if used, shall be commercially available Type I-II and shall be free of lumps and clods.
2.03 Mix Design At least 7 working day before slurry seal placement commences, the Contractor shall submit to the Engineer for approval a laboratory report of tests and proposed mix design covering the specific materials to be used on the project. The percentage of asphalt emulsion proposed in the mix design shall be within the percentage range specified in Section 2.04 “Proportioning” . The tests and mix design shall be performed by a laboratory capable of performing the applicable International Slurry Seal Association (ISSA) tests. The proposed slurry seal mixture shall conform to the requirements specified when tested in accordance with the following tests:
The laboratory report shall be signed by the laboratory that performed the tests and mix design and shall show the results of the tests on individual materials, comparing the test results to those required by the specifications. The report shall clearly show the proportions of aggregate, filler (as determined from the tests, minimum and maximum), water (minimum and maximum), asphalt solids content based on the dry weight of aggregate and set-control agent usage. Previous laboratory reports covering the same materials may be accepted provided they are made during the same calendar year. 2.04 Proportioning Asphalt emulsion shall be added at a rate determined by the mix design and in the range of the table above . A job mix design shall be submitted by the Contractor for approval by the Engineer that conforms to the specification limits, and that is suitable for the traffic, climate conditions, curing conditions and final use. This will include recommended application rate of slurry to suit the job conditions. The Slurry Seal mixture shall be proportioned by the operation of a single start/stop switch or lever which automatically sequences the introduction of aggregate, emulsified asphalt, admixtures, if used, and water to the pug mill. Calibrated flow meters shall be provided to measure both the addition of water and liquid additives to the pug mill. If necessary for workability, a retarding agent, that will not adversely affect the seal, may be used. Water, and retarder if used, shall be added to ensure proper workability and (a) permit uncontrolled traffic on the slurry seal no more than three (3) hours after placement without the occurrence of bleeding, raveling, separation or other distress; and (b) prevent development of bleeding, raveling, separation or other distress within fifteen (15) days after placing the slurry seal. 2.05 Mixing and Spreading Equipment The Slurry Seal shall be mixed in a self-propelled mixing machine equipped with a continuous flow pug mill capable of accurately delivering and automatically proportioning the aggregate, emulsified asphalt, water and additives to a double shafted, multi-blade pug mill mixer capable of minimum speeds of 200 revolutions per minute. A minimum of two operational mixing machines of 12 cubic yard capacity, or larger, shall be maintained on the project. The slurry seal retention time in the pug mill shall be less than three seconds. No retention of mixed slurry seal shall be allowed within the pug mill by gate shut-off or other mechanical means. The mixing machine shall have sufficient storage capacity of aggregate, emulsified asphalt, and water to maintain an adequate supply to the proportioning controls. The mixing machine shall be equipped with hydraulic controls for proportioning the material by volume to the mix. Each material control device shall be calibrated, properly marked, preset and lockable at the direction of the Engineer. The mixing machine shall be equipped with a water pressure system and nozzle type spray bars to provide a water spray immediately ahead of the spreader box. The mixing machine shall be equipped with an approved fines feeder that provides a uniform, positive, accurately metered, pre-determined amount of a mineral filler, if used, at the same time and location that the aggregate is fed. The slurry mixture shall be uniformly spread by means of a controlled spreader box conforming to the following requirements:
2.06 Placing The slurry seal shall not be placed if either the pavement or the air temperature is below 55 degrees F (13C) and falling, but may be applied when both the air and pavement temperature is 45 degrees F (7C) or above and rising. The mixture shall not be applied if high relative humidity prolongs the curing beyond a reasonable time. Before placing the slurry seal, the pavement surface shall be cleaned by sweeping, flushing or other means necessary to remove all loose particles of paving, all dirt and all other extraneous material. 48 hours prior to the slurry seal operations, the contractor shall notify all residents, businesses and agencies with an approved written notice detailing the streets and limits of work to be done along, with the hours of work. The contractor shall also post all streets with temporary "No Parking - Tow Away" signs at 50 foot staggered intervals. These signs shall also state the day of the week and hours of no parking. Immediately before commencing the slurry seal operations, all surface metal utility covers (including survey monuments) shall be protected by thoroughly covering the surface with an appropriate adhesive and paper or plastic. No adhesive material shall be permitted to cover, seal or fill the joint between the frame and cover of the structure. Covers are to be uncovered and cleaned of slurry material by the end of the same work day. Hand tools shall be available in order to remove spillage. Ridges or bumps in the finished surface will not be permitted. The mixture shall be uniform and homogeneous after spreading on the existing surface and shall not show separation of the emulsion and aggregate after setting. Adequate means shall be provided to protect the slurry seal from damage from traffic until such time that the mixture has cured sufficiently so that the slurry seal will not adhere to and be picked up by the tires of the vehicles. For the purpose of this project, the construction zone is defined to include all stockpile staging areas and travel routes to/from streets where the slurry seal is to be applied. The Contractor shall abide, at all times, to the State of California , Department of Transportation's "Manual of Traffic Controls for Construction and Maintenance Work Zones" as applicable to this project. Any deviations shall not be made without prior written approval from the project engineer. 3.01 Measurement Slurry seal will be measured and paid for by the square yard for the actual surface areas covered. 3.02 Payment The contract price paid per square yard for slurry seal shall include full compensation for furnishing all labor, materials, tools, equipment and incidentals and for doing all the work involved in the furnishing and placing of the slurry seal complete in place, including cleaning the surface and protecting the slurry seal until it has set, all as shown on the plans, as specified in these specifications and as directed by the Engineer.
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