Experimental Study And Statistical Analysis On Mechanical Properties Of Full-graded Dam Concrete And Wet-screened Two-graded Aggregate Concrete

Researchers of hydropower technology engineering carried out much research on the strength ratio of the full-graded to the wet-screened two-graded aggregate concrete in recent years. The compressive ratio of them were between0.7and0.9and the splitting tensile strength ratio of them were between0.5and0.7, strength of full-graded concrete being lower than wet-screened two-graded aggregate concrete. There’s no precise and certain value of the ratio till now. Mechanical properties of small concrete specimen produced by wet sieving method, therefore, can’t be a true reflection of the mechanical properties of the full-grade concrete. To study the mechanical properties of concrete used in Xiluodu Dam, cubes with full-graded and wet-screened two-graded aggregate concrete with ages of28d,90d and180d were cast on site to measure the strength of concrete. Then data of concrete strength on other dams was integrated together to analyze the relationship between strength for the full-graded and the wet-screened concrete statistically. Main research work as follows:1、Compressive strength, splitting tensile strength and elastic modulus of full-graded and wet-screened two-graded aggregate concrete cast on Xiluodu Dam construction site were tested and it turned out that these three parameters increases with the increasing of concrete age. According to the experimental results on the concrete with ages of28,90, and180days, the ratio of compressive strength of the full-graded to that of the wet-screened two-graded aggregate concrete is the largest, while the elastic modulus ratio of them is the lowest.2、Ratio of compressive strength and splitting tensile strength of full-graded to that of wet-screened two-graded aggregate concrete acquired by previous researchers and from this test were analyzed statistically by K-S goodness of fit non-parametric test, and it was proved that the ratio were normally distributed. The normal distribution significance probability of compressive strength ratio in k-s test is80.6%and that of splitting tensile strength ratio is42.1%. The mean value of compressive strength ratio of full-graded to wet-screened two-graded aggregate concrete is0.840, and the mean value of splitting tensile strength ratio is0.734. And ratio of compressive strength and splitting tensile strength which can guarantee a95%performance assurance is0.767and0.562respectively. It is of reference value in full-grade concrete strength test and engineering applications that statistical regularity of strength ratio of full-graded to wet-screened two-graded aggregate concrete is confirmed.