Fig.8 shows the relationship between the compressive strength of the rubber concrete and the rubber content. It can be seen that the compressive strength of rubberized concrete declined rapidly with the increase of the crumb rubber content, and the compressive strength of modified rubber concrete decreased slower. The compressive strength of the concrete with4%ordinary crumb rubber content reduced to 23.6MPa from 49.2MPa, losing 52% of its compressive strength. However, the compressive strength of the concrete was 35.1MPa when 4% modified crumb rubber was added to the concrete, improving the compressive strength of concrete with ordinary rubber by 48.7%. This proves that the sur-
face modification of crumb rubber can retard the adverse effect of incorporation of crumb rubber on the compressive strength of concrete.