THE RESEARCH ON THE CRACKING BEHAVIOR OF HIGH PERFORMANCE CONCRETE

The cracking behavior of high performance concrete (denoted as HPC) was systemically studied in the paper. A new test method for concrete cracking behavior, called inducing crack method, is proposed. The method overcomes the shortages of the conventional test method like random crack occuring and uneven material in specimens. The shortages affect the accuracy of testing. A testing system is developed, which can test the age of crack automatically with multi-points monitors. The factors which affect the autogenous shrinkage and drying shrinkage of HPC are studied, and then a method to select raw materials and determine the optimal content and proportions of fly ash and slag to reduce the shrinkage of HPC is proposed. The calculation models of autogeous shrinkage and drying shrinkage of HPC are also put forward, and the cracking behaviors of HPC are studied by the inducing crack method and the ring test system. Moreover, this paper studies the effects of raw materials, especially fly ash and slag, on the cracking behaviors of HPC, and then proposes a method to select raw materials and determine the optimal content and proportions of fly ash and slag to achieve the high anticracking behavior of HPC.