The combination principle is: at least one layer of asphalt surface layer is a type of dense gradation asphalt concrete to prevent water infiltration. If the upper layer using Ⅱ type asphalt concrete, the surface layer shall be used Ⅰ type asphalt concrete, AM type open graded asphalt gravel should not be for the surface layer, can only do link layer.[url=http://doublesteelroller.com]Double Steel Roller - Road Machinery Equipment Manufacturers - Doan Machinery[/url]
SMA structure can be summarized as "more than three less, namely: coarse aggregate, ore powder, asphalt, fine aggregate less." Specifically: ① SMA is an intermittent gradation of asphalt mixture, coarse aggregate ratio of more than 5mm up to 70% to 80%, the amount of slag up to 7% to 13% ("powder than" beyond the usual value of 1.2 limits). (2) to add more asphalt, on the one hand increase the amount of slag, while the use of fiber as a stabilizer; (3) the amount of asphalt more, as high as 6.5% to 7%, the use of high- High adhesion requirements, and want to use penetration is small, softening point, high temperature stability of the bitumen (preferably modified asphalt)
SMA characteristics: Asphalt mastic gravel mixture is currently recognized internationally (more use) of a strong anti-deformation, durability better asphalt surface layer mixture. Due to the good crushing of the coarse aggregate, the mixture has very good high-temperature anti-rutting ability, and at the same time, the low-temperature deformation performance and the water stability are also improved due to the bonding effect of asphalt mastic. Add fiber stabilizer, so that asphalt binder to maintain high viscosity, the paving and compaction effect is better. Intermittent gradation on the surface of the formation of large pores, structural depth, anti-skid performance. While the mixture of the gap is very small, anti-aging properties and durability are very good, thus comprehensively improve the performance of asphalt mixture pavement.
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