Щебеночно-мастичный асфальтобетон (ЩМА)
Broken Rock-Mastic Asphalt Concrete
In recent years more and more heavy freight transport comes onto the motor roads. So the load over the road pavement grew very much. The material that satisfies the modern requirements is broken rock-mastic asphalt concrete, developed in 1960s in Germany, widely used in many countries for creation of upper layers of the road coating. European experience shows – service life of broken rock-mastic asphalt layer serves 20 years and even longer. In recent years in Russia also broken rock-mastic asphalt concrete is used for the highways with heavy traffic, motor roads of I and II category.
Broken rock-mastic asphalt concrete is a type of hot-lay asphalt concrete, providing for higher resistance to water, to shearing (formation of ruts) and also enough roughness of the road coating. The components are: fractioned strong broken cube-like rock (70 - 80 % of mass), broken-rock sand, mineral powder, bitumen binding, stabilizer (cellulose fiber).
The main feature that differs this type of asphalt from the conventional ones is the rigid structure of the layer. Such structure provides for the spreading of the load from the surface down through good contact between the rock pieces. This significantly reduces deformation, both lateral and longitudinal.
Main advantages of broken rock-mastic asphalt concrete are: higher factor of engagement between wheels and road surface, higher wear resistance, including the case of spiked wheels, higher water- and frost-resistance, erosion resistance, high resistance to ageing and fatigue cracking, reduced noise level of traffic, cost of servicing and repair of such road is 2 - 4 times lower.
At the company “Road Service of the Republic of Tatarstan” the technology of stone-matrix asphalt-concrete road pavement was assimilated in 2003.