石粉掺量对机制砂混凝土基本拉伸徐变的影响  

Effects of Stone Powder Content on the Basic Tensile Creep of Manufactured Sand Concrete

作　　者：罗英 曾俊庆 杨群敏 刘东轼 LUO Ying;ZENG Junqing;YANG Qunmin;LIU Dongshi(China Construction Fifth Bureau Civil Engineering Co.,Ltd.,Changsha,Hunan 410004,China)

机构地区：[1]中建五局土木工程有限公司,湖南长沙410004

出　　处：《水利与建筑工程学报》2022年第1期49-55,共7页Journal of Water Resources and Architectural Engineering

摘　　要：混凝土结构时常发生早期开裂现象,降低混凝土结构的耐久性,拉伸徐变可松弛部分拉应力,降低结构开裂风险。为研究不同石粉掺量(0%、6%、12%、18%和24%)对机制砂混凝土基本拉伸徐变的影响,测试其7 d和28 d的弹性模量、1 d~28 d的自收缩和圆环约束下的弹性应变,得到其基本拉伸徐变。研究结果表明:随着石粉掺量的增加,机制砂混凝土的基本拉伸徐变先减小后增大。当石粉掺量小于18%,石粉掺量的增加,混凝土的界面结构改善,硬化水泥浆体的变形能转移到粗骨料,其基本拉伸徐变减小;石粉掺量大于18%,过多的石粉掺量使混凝土界面结构变得薄弱,硬化水泥浆体的变形较难转移到粗骨料,其基本拉伸徐变增大。因此,掺量为18%时,其基本拉伸徐变最小。Early-age cracking often appears in concrete structures which could reduce the durability of the concrete structure.Tensile creep relaxes the tensile stresses partially and mitigates the risk of structural cracking.In order to investigate the effects of stone powder content on the basic tensile creep of manufactured sand concrete with different stone powder contents(0%,6%,12%,18%and 24%).The basic tensile creep was obtained by testing the modulus of elasticity at 7 d and 28 d,the autogenous shrinkage from 1 d to 28 d,and the elastic strain of manufactured sand concrete restrained by circular ring.The results show that the basic tensile creep of manufactured sand concrete decreases and then increases as the amount of stone powder increases.When the amount of stone powder is less than18%,as the amount of stone powder increases,the interface structure of concrete improves,the deformation of the hardened cement paste can be transferred to the coarse aggregate,and its basic tensile creep decreases.The amount of stone powder admixture is greater than 18%,the excess amount of stone powder admixture makes the interface structure of concrete become weak.The deformation of hardened cement paste is more difficult to transfer to the coarse aggregate,and its basic tensile creep increases.Therefore,the basic tensile creep of manufactured sand concrete is minimum at the stone powder content of 18%.

关 键 词：机制砂混凝土 石粉 弹性模量 自收缩 基本拉伸徐变 

分 类 号：TU528[建筑科学—建筑技术科学]