In order to increase the service life of the road and prevent early damage to the road surface, modified asphalt technology was introduced in the surface layer construction to meet the severe test of the rapid growth of traffic volume, large-scale vehicle volume, and severe overloading. The modified asphalt that is widely promoted in China is mainly mixed with the SBS modifier or SBR modifier. The physical properties of the modified asphalt are improved, mainly in softening point, penetration, brittle point, ductility, etc. are improved.
The raw materials of modified asphalt pavement are usually hard, rough, and angular high-quality stones and granite, quartzite, basalt, etc. have these properties, but these stones are often acidic stones. Asphalt contains asphalt acid, asphalt anhydride, etc., and the adhesion is often difficult to meet the requirements. In order to enhance the adhesion between asphalt and aggregates, an SBS modifier is added to the base asphalt to meet the adhesion requirements. In pavement construction, in order to further improve the adhesion of the modified asphalt, an anti-stripping agent is added to the modified asphalt. Add cement, quicklime powder, etc. instead of mineral powder in the filler to increase the adhesion between asphalt and stone, and greatly improve the water stability of the asphalt mixture.
The viscosity of modified asphalt is high, and the construction is difficult, which is quite different from the conventional asphalt pavement construction technology. The quality and road performance of the modified asphalt pavement can be fully guaranteed. The discharge temperature of the modified asphalt mixture is high, generally, the discharge temperature is 170°C-180°C, so the heating temperature of the mineral aggregate should be 180°C-190°C. The mixing time of the modified asphalt mixture should be extended appropriately. Generally, the mixing time should be greater than 45s, including 3-5s of dry mixing, to ensure the uniformity of mineral powder oil absorption. Whether the mixing time is sufficient and whether the mixing method is correct are the key links in the production of high-quality asphalt mixtures. A uniform-quality mixture shows that all the aggregate particles are completely and evenly covered by the asphalt film, and the asphalt is evenly distributed throughout the mixture. No white stones, no lumps of asphalt, black and shiny.