Power asphalt plants are designed for stone mastic asphalt production and we have a module in our software system.Also we produce cellulose dosing unit.With our experienced staff, we provide not only plant sales, but also after-sales operation support and personnel training.

SMA is a relatively thin (12.5–40 mm) gap-graded, densely compacted, HMA that is used as a surface course on both new construction and surface renewal. It is a mixture of asphalt cement, coarse aggregate, crushed sand, and additives. These mixes are different from normal dense grade HMA mixes in that there is a much greater amount of coarse aggregate in the SMA mix. It can be used on major highways with heavy traffic volumes. This product provides a rut resistant wearing course and resistance to the abrasive action of studded tires. This application also provides slow aging and good low-temperature performance.

SMA is used to maximize the interaction and contact among the coarse aggregate fraction in HMA. Asphalt cement and finer aggregate portions provide the mastic that holds the stone in close contact. Typical mix design will generally have 6.0–7.0% medium-grade asphalt cement (or polymer-modified AC), 8–13% filler, 70% minimum aggregate greater than 2 mm (No 10) sieve, and 0.3–1.5% fibers by weight of mix. Fibers are generally used to stabilize the mastic and this reduces the drain off of binder in the mix. Voids are normally kept between 3% and 4%. Maximum particle sizes range from 5 to 20 mm (0.2 to 0.8 in.).

Mixing, transportation, and placement of SMA use the customary equipment and practices with some variations. For example, higher mixing temperature of about 175°C (347°F) is usually necessary because of coarser aggregate, additives, and relatively high viscosity asphalt in SMA mixes. Also, when cellulose fibers are used, the mixing time has to be increased to allow for proper mixing. Rolling begins immediately after placement to achieve density quickly before the mix temperature decreases significantly. Compaction is usually accomplished by use of 9–11 tonne (10–12 ton) steel-wheeled rollers. Vibratory rolling may also be used with caution. Compared to normal dense-graded HMA, SMA has better shear resistance, abrasion resistance, cracking resistance, and skid resistance, and is equal for noise generation. Table 10.7 represents the comparison of the gradation of SMA used in the United States and Europe.