自密实混凝土强度尺寸效应的试验与数值仿真

Tests and numerical simulation of size effect on the strength of self-compacting concrete

自密实混凝土(SCC)是通过掺加高效减水剂而得到的流动性极佳的混凝土,具有很高的流动性,不离析、不泌水,无须振捣便可达到自密实的效果。本文对边长为70.7mm的立方体小试件在不同边界条件下进行单轴压缩试验,用以研究端部效应对SCC强度及破坏形态的影响。为了避免端部效应对尺寸效应的影响,本文考虑减摩措施,对边长为70.7mm、100mm、150mm、200mm、300mm立方体SCC试件进行单轴压缩试验,试验结果表明,随着试件尺寸的增加,混凝土的单轴抗压强度不断减低,即呈现出明显的尺寸效应现象,符合Weibull强度统计理论。此外,基于混凝土细观概率模型进行相应的数值仿真,通过对比数值模拟结果与试验结果,验证了该模型能较好地模拟混凝土尺寸效应现象。

Self-compacting concrete（SCC） is a concrete added with super plasticizer and it possesses high fluidity without segregation and bleeding.Needless to vibrate,it can flow and be compacted by itself.In this work,uniaxial compression tests of 70.7mm-edged cube SCC specimen under different boundary conditions were carried out,and the end effects on concrete strength and failure pattern were studied.A series of tests on different specimen sizes,70.7mm,100mm,150mm,200mm and 300mm,were conducted,and to avoid the end effects caused by different specimen sizes a friction-reducing measure was adopted.The results show a decreasing trend in the uniaxial compression strength of SCC with the increase of specimen size,and this trend demonstrates an obvious size effect and agrees well with the Weibull statistical theory.Numerical simulations based on a meso-scale probabilistic model were also made for these specimens.A comparison with the experiment shows that this model produces satisfactory results in terms of the size effect.