Experimental Study On High-performance Concrete At Early Age Autogenous Shrinkage

High performance concrete (HPC) is one new kind of high-tech concrete that came forth in the early age of 1990's. With about ten years' history, HPC has gradually been used in various building projects, and consequently brought human being great economy benefits and social benefits. But that HPC is used extensivelybrings another technical problem -almost all large-scale building that wereconstructed with HPC have different degree cracking. Former researches testified: it is the main reason of HPC's cracking that autogenous shrinkage of HPC is more than common concrete's and it mainly occurs at early age of concrete, then HPC often has a great deal micro-cracks before stripping.Therefore, the paper studied influence of two factors on autogenous shrinkage of HPC systematically. These two factors are strength level, dosage of fly ash.With two investigations and referred to the equipment of shrinkage cracking of high-strength concrete researched by Karl Wiegrink. I developed the equipment for my research. Used a new test method, resistance strain gauge is affixed to concrete cirque and steel cirque to measure strain data. By these data explained developing trend of autogenous shrinkage of HPC at early age.By these experience, I gain conclusion: with the increasing of concrete strength, autogenous shrinkage of HPC at early age increase, With the increasing of dosage of fly ash concrete, autogenous shrinkage of HPC decreases. By these experience, the paper firstly brought forward three concepts: turning point of autogenous shrinkage of concrete, continue maintain time, fly ash concrete strength balanced point. By these experience of fly ash concrete research, in my view, the compressive strength of fly ash concrete with 56 or 60 age should be standard compressive strength in China.