废弃纤维再生混凝土劈裂抗拉强度尺寸效应试验

Experimental Study on Size Effect of Splitting Tensile Strength of Waste Fiber Recycled Concrete

目的研究再生骨料取代率、废弃纤维掺入量和混凝土强度等级对废弃纤维再生混凝土立方体试件劈裂抗拉强度的尺寸效应.方法对15组边长为100 mm、150 mm、200 mm的立方体试件进行劈裂抗拉试验,通过尺寸效应度评价各参数对尺寸效应的影响规律;采用最小二乘法,验证经典尺寸效应理论模型对废弃纤维再生混凝土的适用性.结果随着再生骨料取代率的增加,劈裂抗拉强度尺寸效应增加;随着废弃纤维掺入量的增加,劈裂抗拉强度的尺寸效应先减小后增加,当废弃纤维掺入量为0. 12%时,尺寸效应现象较小;混凝土的强度等级越高,强度的尺寸效应现象越明显;两种经典尺寸效应理论试验数据的拟合相关系数介于0. 946～0. 999.结论废弃纤维再生混凝土的劈裂抗拉强度存在尺寸效应现象,与普通混凝土随强度等级的变化规律一致,Bazant尺寸效应理论无切口情况修正和Carpinteri分形尺寸效应适用于废弃纤维再生混凝土尺寸效应的分析.

In this paper,the influence of the strength grade,the replacement rate of recycled aggregates and the volume incorporation of waste fibers on the splitting tensile strength size effect of waste fiber recycled concrete were studied.A total of15sets of cube specimens with side lengths of100mm,150mm and200mm were subjected to splitting tensile tests and the effect of various design variables on the size effect were evaluated by the size effect degree.The applicability of the theoretical model of size effect on waste fiber recycled concrete is verified by the least square method.As the replacement rate of recycled aggregates increases,the size effect of splitting tensile strength increases.With the increase of the volume incorporation of the waste fibers,the size effect of the splitting tensile strength decreases first and then increases.When the volume incorporation of waste fibers is0.12%,the size effect is thesmallest.The higher the strength grade of concrete is,the more obvious the size effect of strength is.The fitting correlation coefficients between the two classical size effect theory test datas between0.946~0.999.The conclusion of this paper is that the splitting tensile strength of waste fiber recycled concrete has a size effect and is consistent with the change of strength grade of ordinary concrete.The Bazant size effect theory and Carpinteri fractal size effect are suitable for the analysis of the size effect of waste fiber recycled concrete.