Micro-Cracking Around Deformed Rinforcing Bar in Ultra High-Strength Reinforced Concrete Members

In this research, Several different ultra-high-strength concretes with water to binder ratio of 0.15 were developed and experimental results of basic physical data, self-induced stress of concrete with different restraint ratio and existence of crack around rebar due to autogenous shrinkage are reported. The major experimental results are: 1) The cracks around deformed reinforcing bar due to volume change of concrete experimentally confirmed, 2) Drying shrinkage of ultra-high-strength concrete affects restraint stress of concrete even it is believed to be close, 3) it is possible to add chemical pre-stress of the ultra-high strength concrete with belite-rich cement, expansive additive and reducing shrinkage admixture.