Asphalt Rubber Stress Absorbing Treatments
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 Cal Trans standard specifications and to these special provisions.
A Certificate of compliance shall be furnished to the engineer in accordance with section 6 - 1.07, "Certificates of Compliance,"of the standard specifications for each material used in aasphalt-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.
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 - Paving asphalt to be used in the asphalt-rubber binder shall be grade AR-400 and shall conform to Section 92,"Asphalts,"of the Standard Specifications and these special provisions.
The paving asphalt for use in asphalt-rubber shall be modified with an asphalt modifier.
ASPHALT MODIFIER - The asphalt modifier will be resinous, high flash point, aromatic hydrocarbon compound and shall conform to the following requirements:
* The symbol"X"is the viscosity of the asphalt modifier the Contractor proposes to furnish. The Value"X"which the contractor proposes shall be between the limits 19 and 36 and shall be submitted in writing to the engineer. Any proposed change requested by the contractor, in the value"X"shall require a new asphalt-rubber design.
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.
CRUMB RUBBER MODIFIER (CRM) - Crumb rubber modifier 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 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 Transportation Laboratory, Pavement Consulting Services 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 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 ad 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.
ASPHALT RUBBER BINDER - Asphalt rubber binder shall consist of a mixture of paving asphalt, asphalt modifier and crumb rubber modifier.
At least two weeks before it's 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
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:
Note: 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.
SCREENINGS - Screenings shall conform to the requirements in these special provisions and section 37-1.02,"Materials", of the 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:
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.
EQUIPMENT - The contractor shall utilize the following equipment for asphalt rubber seal coat operations:
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.
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 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 23-30 psy. 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.
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 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 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. It shall be operated in 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.
FLUSH COAT - This work shall consist of an application of fog seal coat and sand cover to the surface of asphalt rubber seal coat as shown on the plans, and in accordance with the provisions in section 37-1"Seal Coats", of the Standard Specifications and these special provisions.
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.
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 or CSS1H, 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 gsy. The exact rate of application will be determined by the engineer.
Attention is directed to section 7-1.11,"Preservation of Property", of the 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.
SAND COVER - Sand for sand cover shall conform to the fine aggregate grading requirements in section 90-3.03,"Fine Aggregate Grading", of the 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 psy. The exact rate will be determined by the engineer.
Sand cover shall be applied immediately following application of the fog seal.
A Certificate of compliance shall be furnished to the engineer in accordance with section 6 - 1.07, "Certificates of Compliance,"of the standard specifications for each material used in aasphalt-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.
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 - Paving asphalt to be used in the asphalt-rubber binder shall be grade AR-400 and shall conform to Section 92,"Asphalts,"of the Standard Specifications and these special provisions.
The paving asphalt for use in asphalt-rubber shall be modified with an asphalt modifier.
ASPHALT MODIFIER - The asphalt modifier will be resinous, high flash point, aromatic hydrocarbon compound and shall conform to the following requirements:
| ASPHALT MODIFIER ASTM |
||
| Test Parameter | Designation | Requirement |
| Viscosity, cSt. at 100C | D445 | X+/- 3* |
| Flash Point, COC, F | D92 | 405 min. |
| Molecular Analysis: Aspaltenes, percent by weight |
D2007 | 0.1 max. |
| Aromatics, percent by weight | D2007 | 55 min. |
* The symbol"X"is the viscosity of the asphalt modifier the Contractor proposes to furnish. The Value"X"which the contractor proposes shall be between the limits 19 and 36 and shall be submitted in writing to the engineer. Any proposed change requested by the contractor, in the value"X"shall require a new asphalt-rubber design.
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.
CRUMB RUBBER MODIFIER (CRM) - Crumb rubber modifier 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 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 Transportation Laboratory, Pavement Consulting Services 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 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:
| SCRAP TIRE CRUMB RUBBER MODIFIER | ||
| Test Parameter | Percent | |
| Min. | Max. | |
| Acetone Extract | 6.0 | 16.0 |
| Ash Content | - | 8.0 |
| Carbon Black Content | 28.0 | 38.0 |
| Rubber Hydrocarbon | 42.0 | 65.0 |
| Natural Rubber Content | 22.0 | 39.0 |
| HIGH NATURAL CRUMB RUBBER MODIFIER | ||
| Test Parameter | Percent | |
| Min. | Max. | |
| Acetone Extract | 4.0 | 16.0 |
| Rubber Hydro carbon | 50.0 | - |
| Natural Rubber Content | 40.0 | 48.0 |
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 ad 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.
| CRM GRADATIONS | ||
| Sieve Size | Scrap Tire CRM | High Natural CRM |
| Percent Passing | Percent Passing | |
| No.8 | 100 | 100 |
| No.10 | 98-100 | 100 |
| No.16 | 45-75 | 95-100 |
| No.30 | 2-20 | 35-85 |
| No.50 | 0-6 | 10-30 |
| No.100 | 0-2 | 0-4 |
| No.200 | 0 | 0-1 |
ASPHALT RUBBER BINDER - Asphalt rubber binder shall consist of a mixture of paving asphalt, asphalt modifier and crumb rubber modifier.
At least two weeks before it's 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
- Source and grade of paving asphalt.
- Source and identification (or type) of modifiers used.
- Percentage of asphalt modifier by weight of paving asphalt.
- Percentage of the combined blend of paving asphalt and asphalt modifier by total weight of asphalt rubber binder to be used.
- Laboratory test results for test parameters shown elsewhere in these special provisions.
- Source and identification (or type) of scrap tire and high natural CRM.
- Percentage of scrap tire and high natural CRM by total weight of the asphalt rubber blend.
- If CRM from more than one source is to be used, the above information will be required for each CRM source used.
- Laboratory test results for test parameters shown elsewhere in these special provisions.
- Laboratory test results of the proposed blend for the test parameters shown elsewhere in these special provisions.
- The minimum reaction time and temperature.
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:
| BLENDED ASPHALT RUBBER BINDER | |||
| Test Parameter |
ASTM Test Method |
Requirement | |
| Min. | Max. | ||
| Cone Penetration @ 77 F. 1/10 mm |
D217 | 25 | 70 |
| Resilience @ 77 F | D3407 | 18 | - |
| Field Softening Point. F. |
D36 | 125 | 165 |
| Viscosity @ 375 F. Centipoise |
See Note | 1,500 | 3,500 |
Note: 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.
SCREENINGS - Screenings shall conform to the requirements in these special provisions and section 37-1.02,"Materials", of the 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 GRADING REQUIREMENT 3/8"maximum |
|
| Sieve Size | Percentage Passing |
| 1/2 | 100 |
| 3/8 | 70-85 |
| No. 4 | 0-15 |
| No. 8 | 0-5 |
| No. 200 | 0-1 |
The screenings grading shall conform to the following requirements prior to precoating with paving asphalt:
| SCREENINGS GRADING REQUIREMENT 1/2" maximum |
|
| Sieve Size | Percentage Passing |
| 3/4 | 100 |
| 1/2 | 95-100 |
| 3/8 | 70-85 |
| No. 4 | 0-15 |
| No. 8 | 0-5 |
| No. 200 | 0-1 |
Screenings shall conform to the following quality requirements immediately prior to preheating:
| SCREENINGS QUALITY REQUIREMENTS | ||
| Test Parameters | California Test | Requirements |
| Los Angeles Rattler Loss (100 Revolutions) |
211 | 10 max. |
| Los Angeles Rattler Loss (500 Revolutions) |
211 | 40 max. |
| Film Stripping | 302 | 25 max. |
| Cleanness Value | 227 | 80 min. |
| Durability | 229 | 52 min. |
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.
EQUIPMENT - The contractor shall utilize the following equipment for asphalt rubber seal coat operations:
- Self propelled power brooms capable of cleaning the existing pavement and removing loose screenings without dislodging screenings set in the asphalt rubber binder. Gutter brooms or steel tinned brooms shall not be used.
- Pneumatic tired rollers conforming to the requirements specified in section 39- 5.02,"Compacting Equipment", of the Standard Specifications except that the rollers shall have an air pressure of 100 pounds per square inch and maintained so that the air pressure will not vary more than +/- 5 psi in each tire. A sufficient number of rollers shall be used so that one complete coverage will be provided in one pass.
- A self propelled, computerized, screenings spreader, equipped with a screenings hopper in the rear, belt conveyors to carry the screenings to the front of the spreader hopper. The screenings spreader shall be capable of providing a uniform spread rate over the entire width of the traffic lane in one application
- An asphalt heating tank equipped to heat and maintain the blended paving asphalt and asphalt modifier mixture at the necessary temperature before blending with crumb rubber modifier (CRM). This unit shall be equipped with a thermostatic heat control device, a temperature reading device and shall be accurate within 5 F and shall be of the recording type.
- A mechanical mixer for the complete, homogenous blending of paving asphalt, asphalt, asphalt modifier, and CRM. Paving asphalt and asphalt modifier shall be introduced into the mixer. The blending system shall be capable of varying rate of delivery of paving asphalt and asphalt modifier proportionate with the delivery of CRM. During the proportioning and blending of the liquid ingredients, the temperature of paving asphalt and the asphalt modifier shall not vary more than +/- 25 F. The paving asphalt feed, the asphalt modifier feed and CRM feed shall be equipped with devices by which the rate of feed can be determined during the proportioning operation. The liquid and dry ingredients shall be fed directly into the mixer at a uniform and controlled rate. The rate of feed to the mixer shall not exceed that which will permit complete mixing of all the materials. Dead areas in the mixer, in which the material does not move or is not sufficiently agitated, shall be corrected by a reduction in the volume of material or by other adjustments. Mixing shall continue until a homogeneous mixture of uniformly distributed and properly blended asphalt rubber binder of unchanging appearance and consistency is produced. The contractor shall provide a safe sampling device capable of delivering a representative sample of completed asphalt rubber binder of sufficient size to permit required tests.
- An asphalt rubber binder storage tank equipped with a heating system to maintain the proper temperature of the asphalt rubber binder and an internal mixing unit capable of maintaining a homogeneous mixture of blended paving asphalt, asphalt modifier and CRM.
- A self propelled truck or trailer mounted distributor, equipped with an internal mixing unit capable of maintaining a homogenous mixture of blended paving asphalt, asphalt modifier, and CRM. The distributor shall have a pump or pumps capable of spraying asphalt rubber binder within +/- 0.05 gallons per square yard of the specified rate. The distributor shall have a fully circulating spray bar capable of applying the asphalt rubber without a streaked or otherwise irregular pattern. The distributor shall be equipped with a tachometer, pressure gages, volume measuring devices and thermometer. The distributor shall have a platform on the rear of the vehicle and an observer shall accompany the distributor. The observer shall ride in such a position, that all spray nozzles are in full view and readily accessible for unplugging any plugged nozzles, should they occur.
- Tailgate discharge trucks for hauling screenings shall be equipped with a device to lock on to the hitch at the rear of the screenings spreader. Haul trucks shall be compatible with the screenings spreader so that the dump bed will not push down on the spreader when fully raised or have too short of a bed which results in spilling while dumping into the receiving hopper.
All equipment shall be approved by the engineer prior to use.
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.
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 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 23-30 psy. 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.
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 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 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. It shall be operated in 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.
FLUSH COAT - This work shall consist of an application of fog seal coat and sand cover to the surface of asphalt rubber seal coat as shown on the plans, and in accordance with the provisions in section 37-1"Seal Coats", of the Standard Specifications and these special provisions.
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.
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 or CSS1H, 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 gsy. The exact rate of application will be determined by the engineer.
Attention is directed to section 7-1.11,"Preservation of Property", of the 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.
SAND COVER - Sand for sand cover shall conform to the fine aggregate grading requirements in section 90-3.03,"Fine Aggregate Grading", of the 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 psy. The exact rate will be determined by the engineer.
Sand cover shall be applied immediately following application of the fog seal.
Last Updated (Thursday, 10 December 2009 16:37)