A Study on Shrinkage Property and Evaluation Method of Rapid Repair Concrete

The properties of early shrinkage,autogeneous shrinkage,dry shrinkage and the effects of test time of original length of specimen on the evaluation of shrinkage of rapid repair concrete(RRC) are studied in this paper.The results show that the autogenous shrinkage is the main part of shrinkage of RRC,and the increasing speed of shrinkage of RRC is quick than that of ordinary Portland cement concrete(OPC) before 3 d age,but equivalent to OPC after 3 d age,so the shrinkage of RRC is serious than that of OPC.The test time of original length of specimen effects on the evaluation of shrinkage of RRC significantly.The shrinkage of RRC would be estimated lowly if testing the original length of specimen at 2 d or 3 d age.Therefore,it is suggested that the demoulding of specimens are carried out when the compressive strength of RRC arrives at 5 to 7 MPa,and then the original length of specimens is tested immediately after the specimens are kept in the constant temperature and humidity room for 1 h.