Study On Ordinary-Strength High Performance Concrete

Ordinary-strength concrete is being widely used. Under the situation of widespread concern on the durability of concrete, the high performance of the ordinary-strength concrete seems to be of great importance, which will be helpful to conservation of resources, energy and funds.The effect of various mix proportion parameters, such as unit binder content, unit water content, sand ratio, and air content, on the performance of ordinary-strength concrete were experimentally studied, and suitable range for C40 high-performance concrete is proposed on this base, that is, unit binder content 360 ~400 kg/ m3, water binder ratio 0.39-0.47, and sand ratio 38%~40%.Grade C40 high-performance concrete is prepared by adding grade I fly ash, superplasticizer and air entraining agent. The concretes have excellent workability, with high slump (about 200mm) and low slump lossless than 40mm) after 1h. The impermeability grade of the hardened concrete can reach as high as P12.The hardened concrete can resist more than 200 times of freezing -thawing test.According to service-life estimating model of concrete carbonization andfreezing-thawing: t1 = 43.84(X1/X2)1/b and Y = R D/KN, service-life estimation of GradeC40 concrete is made and freezing-thawing test. The result suggests that the estimating service-life of the Grade C40 high-performance concrete based on carbonization are more than 100 years when the concrete protecting layer is thicker than 30mm, and it can also be used around Jiangsu and Zhejiang for more than 100 years based on freezing-thawing test. High performance ordinary-strength concrete is thus proposed.Through MIP and XRD methods, micro-mechanism analysis on the C40 concrete suggests that C40 high-performance concrete have less large pores, more tiny pores and more reasonable pore distribution than reference concrete. In the hardening paste, The amount of Ca(OH)2 is obviously less than the reference sample.