AASHTO MP 8-07 pdf free download
AASHTO MP 8-07 pdf free download.Stone Matrix Asphalt (SMA).
3. TERMINOLOGY
3.1. stone ,natrLv asphalt (SMA)—a hot-mix asphalt (HMA) consisting of two parts, a coarse aggregate skeleton and a rich asphalt hinder mortar. The mixture must have an aggregate skeleton with coarse aggregate-on-coarse aggregate contact (generally referred to as stone-on-stone contact). The coarse aggregate is generally considered to be that fraction of the aggregate retained on the 4.75-mm (No. 4) sieve but may be designated as other sizes.
3.2. air voids (V)—the total volume of the small pockets of air between the coated aggregate particles throughout a compacted paving mixture, expressed as a percent of the bulk volume of the compacted paving mixture (Note I).
Note 1—Term defined in the Asphalt Institute Manual MS-2.
3.3. voids iii the mineral aggregate (VMA)—the volume of the intergranular void space between the aggregate particles of a compacted paving mixture that includes the air voids and the effective binder content, expressed as a percent of the total volume of the specimen (Note 1).
3.4. voids in the coarse aggregate (VC’A)—the volume between the coarse aggregate particles. This volume includes filler, fine aggregate. air voids, asphalt binder, and stabilizing additive (if used).
3.5. SMA mortar—a mixture of asphalt binder, filler jrnaterial passing the 0.075-mm (No. 200) sievel, and stabilizing additive.
3.6. stabilizing additive—either cellulose or mineral Ii her.
4. SIGNIFICANCE AND USE
4.1. This standard may be used for designing and evaluating material and mixture properties for SMA.
5. ASPHALT BINDER REQUIREMENTS
5.1. The asphalt binder shall be a performance grade meeting the requirements of M 320, which is appropriate for the climate and traffic-loading conditions at the site of the paving project. Guidance for the selection of the appropriate asphalt binder is provided in M 323.
7. MINERAL FILLER
7.1. Mineral filler shall consist of finely divided mineral matter such as crusher fines and fly ash. At the time of use, it should he sufficiently dry to flow freely and essentially free from agglomerations. Filler shall be free from organic impurities and have a plasticity index not greater than four.
Note 2—It is recommended that mineral fillers with modified Rigden voids (IS 127) higher than 50 percent not be used in SMA. Experience has shown that fillers exceeding 50 percent excessively stiffen the SMA mortar.
8. STABILIZING ADDITIVE
8.1. A stabilizer such as cellulose or mineral fiber will be added to the mixture. The dosage rate for cellulose shall be approximately 0.3 percent or more by total mixture mass and sufficient to prevent draindown. For mineral fibers, the dosage rate shall be approximately 0.4 percent by total mixture mass and sufficient to prevent draindown. The maximum draindown will be 0.3 percent by weight of the mix when held at the plant temperature for one hour.
Note 3—If the draindown from the plant-produced samples exceeds the draindown from laboratory-prepared samples, the quantity of the stabilizer should be increased. To maximize durability (through binder volume), fibers also can be added regardless of draindown.
9. SMA DESIGN REQUIREMENTS
9.1. The combined aggregates shall conform to the gradation requirements of Table 3. When the hulk specific gravities of the different stockpiles to be used in the mixture vary by more than 0.2, the trial blend gradations shall be based on the volumetric percentage.
Note 4—For low-traffic-volume roadways or colder climates, target air void contents less than 4.0 percent can be used, but should not be less than 3.0 percent.
Note 5—When aggregates have a Los Angeles Abrasion loss value greater than 30 percent, the desirable number of SGC design gyrations is 75.
Note 6—See PP 41 for instructions on calculating VCA11x and VCADRC.
Note 7—Experience has shown that binder contents should be from 6.0 to 7.0 percent. Lowering the binder content below 6.0 percent can detrimentally affect the durability of the SMA. When an SMA mix cannot be designed within the minimum binder content requirements of Table 4 using the available aggregates, refer to the guidance given on this issue in PP 41.
9.3. The tensile strength ratio (TSR) of the SMA shall be at least 0.80, at 6.0 ± 1.0 percent air voids, when tested in accordance with T 283.
9.4. Draindown sensitivity shall be determined on the SMA mixture in accordance with T 305 at the anticipated plant-production temperature and shall not exceed 0.3 percent.AASHTO MP 8-07 pdf download.
