1. Definition of rubber powder modified bitumen
Rubber powder modified bitumen (bitumen Rubber, referred to as AR) is a new type of high-quality composite material. Under the combined action of heavy traffic bitumen, waste tire rubber powder and admixtures, the rubber powder absorbs resins, hydrocarbons and other organic matter in the bitumen, and undergoes a series of physical and chemical changes to moisten and expand the rubber powder. The viscosity increases, the softening point increases, and the viscosity, toughness, and elasticity of rubber and bitumen are taken into account, thereby improving the road performance of rubber bitumen.
"Rubber powder modified bitumen" refers to the rubber powder made from waste tires, which is added as a modifier to the base bitumen. It is made through a series of actions such as high temperature, additives and shear mixing in a special special equipment. adhesive material
The modification principle of rubber powder modified bitumen is a modified bitumen cementing material formed by the full swelling reaction between tire rubber powder particles and matrix bitumen under fully mixed high-temperature conditions. Rubber powder modified bitumen has greatly improved the performance of base bitumen, and is superior to modified bitumen made of currently commonly used modifiers such as SBS, SBR, EVA, etc. In view of its excellent performance and great contribution to environmental protection, some experts predict that rubber powder modified bitumen is expected to replace SBS modified bitumen. 

2. Characteristics of rubber powder modified bitumen
The rubber used for modified bitumen is a highly elastic polymer. Adding vulcanized rubber powder to the base bitumen can achieve or even exceed the same effect as styrene-butadiene-styrene block copolymer modified bitumen. The characteristics of rubber powder modified bitumen include:
2.1. The penetration decreases, the softening point increases, and the viscosity increases, indicating that the high-temperature stability of the bitumen is improved, and the rutting and pushing phenomena of the road in summer are improved.
2.2. Temperature sensitivity is reduced. When the temperature is low, the bitumen becomes brittle, causing stress cracking in the pavement; when the temperature is high, the pavement becomes soft and deforms under the influence of the vehicles carrying it. After modification with rubber powder, the temperature sensitivity of the bitumen is improved and its flow resistance is improved. The viscosity coefficient of the rubber powder modified bitumen is greater than that of the base bitumen, indicating that the modified bitumen has higher resistance to flow deformation.
2.3. Low temperature performance is improved. Rubber powder can improve the low-temperature ductility of bitumen and increase the flexibility of bitumen.
2.4. Enhanced adhesion. As the thickness of the rubber bitumen film adhered to the surface of the stone increases, the bitumen pavement's resistance to water damage can be improved and the road life can be extended.
2.5. Reduce noise pollution.
2.6. Increase the grip between the vehicle tires and the road surface and improve driving safety.