PROBLEM TO BE SOLVED: To obtain a modifying agent used for modifying an asphalt/ cement(AC), having a compatibility with the AC and capable of improving the practical performance of the asphalt concrete prepared by using the AC modified by using the same additive. SOLUTION: This modifying agent for the AC is a mixed composition of (1) a high molecular weight SBR (RH) having at least approximately 300,000 weight-average molecular weight (Mw) and (2) a low molecular weight SBR (RL) having approximately =280,000 Mw, and has an approximately (80/20)-(25/75) RH/RL ratio and at least 5% difference between the bonded styrene contents in the RH and RL. The composition has an approximately 50,000-150,000 number average-molecular weight and a light dispersion/light refraction ratio in 1.8-3.9 range. The modified AC prepared by using the above emulsion-polymerized SBR composition has a high level of strength, elongation, tenacity and toughness and the concrete containing the AC is proven to have a high resistance against depression, wheel truck and low temperature tearing.
展开▼
