不同来源再生混凝土抗压强度分布特征研究

通过249块立方体试块抗压强度试验,研究了水灰比为0.74、0.55和0.43的不同来源再生混凝土抗压强度及概率分布特征。试验结果表明,不同强度等级废混凝土混和后得到的再生粗集料,将显著降低再生混凝土的抗压强度;不同来源再生混凝土抗压强度的均值较单一来源再生混凝土减小,而方差和变异系数增大;采用正态分布模型对不同来源再生混凝土抗压强度的分布进行了检验,利用Monte-Carlo模拟方法进一步验证了该分布规律。最后根据统计分析和Bayes估计结果,给出了不同来源再生混凝土抗压强度标准差的建议取值,即在强度等级低于C20时其值取为5.0MPa,在强度等级为C20其值取为6.0MPa。

Compressive strength distribution of recycled aggregate concrete derived from different origins

In order to investigate the compressive strength distribution of recycled concrete that was derived from different origins, 249 cubes with three water-cement ratios (W/C) of 0.74, 0.55 and 0.43 were designed and tested under laboratory condition. It was found that recycled coarse aggregate which was derived from mixed original concrete of different compressive strength could reduce the compressive strength of recycled aggregate concrete remarkably. The mean value for the compressive strength of recycled aggregate concrete derived from different origins was smaller than that of recycled aggregate concrete that was derived from single origin, while the standard deviation as well as the coefficient of variation of compressive strength were much larger. Normal model was used to describe the distributions for the compressive strength, and the Monte-Carlo simulation technique was employed to study the suitability of the distribution for the compressive strength. Finally, based on the statistical analysis and the results of Bayes estimations, the standard deviations for the compressive strength of recycled aggregate concrete derived from different origins were proposed, that is, when the grade of compressive strength of recycled aggregate concrete is below C20, the value could be 5.0 MPa, when the grade of compressive strength of recycled aggregate concrete is C20, the value could be 6.0 MPa.