EFFECTS OF RUBBING ACTION IN MANUFACTURING PROCESS OF RECYCLED COARSE AGGREGATE FROM WASTE CONCRETE ON STRENGTH AND DURABILITY OF RECYCLED CONCRETE PRODUCTS

摘要

In 2000, the quantity of Japan's waste concrete amounted to 35 million tons and the percentage of their recycling was 96%, as being reused mostly into lower base material in road pavements. From the effective utilization of finite resources, it is necessary to study how to reuse recycled aggregate from waste concrete into new concrete. This paper describes about effects of the rubbing action in the third manufacturing process of recycled coarse aggregate from waste concrete on the strength and durability of recycled concrete products. The recycled coarse aggregate rubbed in the third process remarkably improved their physical properties and their strength increased 42% than the coarse aggregate recycled in the second process. The strength of concrete products reused the third processed coarse aggregate increased 21% at 14-day age and 17% at 28-day age, compared with the concrete products reused the second processed coarse aggregate. The freeze-thaw durability of both concrete products was almost similar. Consequently, influencing the rubbing action in the manufacturing process improved both qualities of recycled coarse aggregate and recycled concrete products, because the rubbing action caused to make round aggregate corner while removing mortar from aggregate surface.