Study Of C80 Slag High Strength Concrete

High strength & high performance concrete came into being as a new construction material in 1980's. For its desired properties including high strength, long durability and good workability, it has been shown remarkably economic in replacing traditional concrete structure and building special structure using in the aggressive environment. It has been prophesied that the concrete with strength over 100MPa will be widely used.Through systematically analyzing the composition and structure of concrete from three levels of macroscopic, microcosmic and ultra- microcosmic, the author of this paper found that the mechanical properties and durability of concrete depended on mainly its composition and structure. The interface, which is one of three composition of concrete (hardened cement paste, aggregate and interface), is the most weak zone in concrete. Therefore, the key to improve strength and durability of the concrete is to decrease flaws of concrete, especially to meliorate the structure of interface, which will improve the compactness and cohesion of interface, thus improve the strength and durability of the concrete.By using the method of adding ordinary Portland cement with fine mineral admixture and super plasticizer and the mixing process of Stone Enveloped with Cement, the high strength & high performance concrete with strength of 85MPa and slump of 120mm are produced, and the method of producing C80 high strength & high performance concrete are recommended in this paper.This experiment is carried out complying with orthogonal test-schema, then the author carry on systematic statistical analysis to the test data with SPSS. It analyzes the effect of water/binder ratio, percentage of silica fume and slag and super plasticizer on the strength of the high strength & high performance concrete. And then, the optimum of mix proportions of every composition is acquired according to the comprehensiveequilibration theory. Simultaneously, regression analysis is carried out between the 28d compressive strength of HSC and the binder/water ratio with no variation of other factors. The result of the experiments shows that the effects of compound pozzolanic and micro-aggregate have been produced when silica fume and slag were added into concrete together. And the Stone Enveloped with Cement can meliorate distinctly the structure of the transition zone of interface, thus the strength of concrete is improved.