环向约束条件下高强混凝土早期开裂

为研究环向约束条件下高强混凝土早期开裂趋势,在单面干燥条件下应用非接触式混凝土收缩变形测定仪测试了水灰比为0.26,0.31和0.40试件的早期自由收缩变形.通过静压试验测试了试件早期弹性模量发展,通过改进环向约束试验观测了环向约束条件下各试件内部的收缩应力及应力梯度.结果表明,水灰比越小,单面干燥条件下受约束高强混凝土早期开裂危险性越高,开裂发生时间越早;开裂时间、开裂时弹性模量在很大程度上决定了早期开裂特点.

Study on early-age cracking of high strength concrete under circumferentially restrained condition

In order to study the early-age cracking tendency of high strength concrete under circumfer-entially restrained condition, the non-contact shrinkage measuring device was developed to determine the free shrinkage of high strength concrete with water to cement ratio of 0. 26, 0. 31 and 0.40 under the condition that the casting surface was exposed to drying environment. The early-age elastic modulus of the specimens was investigated through the static compression test. The inner shrinkage stress and stress gradient of restrained specimens were investigated through the modified restrained ring test. The results indicate that the high strength concrete with lower water to cement ratio exhibits higher early-age cracking tendency and would crack at earlier time. The early-age cracking characteristic of high strength concrete is mainly determined by its cracking time and elastic modulus at cracking time.