Keiichi Imamoto

HIGH QUALITY RECYCLED AGGREGATE CONCRETE (HIRAC) PROCESSED BY DECOMPRESSION AND RAPID RELEASE

Quality of concrete with recycled aggregate is generally lower than that of virgin aggregate. The main reason is that, recycled aggregate with its higher water absorption property has more porous mortar matrix around than that of the virgin aggregate and hence develops an inferior bond. In order to improve the quality of recycled aggregate concrete, an innovative method is proposed in this paper. High quality recycled aggregate concrete (HiRAC) can be obtained through a decompression and rapid release (DC-RR) procedure applied after normal mixing of concrete with recycled aggregate. Through the DC-RR procedure, the quality of transition zone between aggregate and cement matrix can be dramatically improved. In this paper, experimental studies are described on the effectiveness of DC-RR procedure on some of the mechanical and physical properties of recycled aggregate concrete. It was found that, by applying the DC-RR procedure, compressive strength of recycled aggregate concrete can be increased by about 20%; creep and carbonation depth can be reduced by about 20% and 30%, respectively.