加掺合料高性能混凝土早龄期收缩特性

采用智能型非接触式微位移传感器法，对加掺合料高性能混凝土从成型后6h到3d龄期内的自生收缩和单面干燥条件下的总收缩进行试验研究，并测量了不同龄期混凝土的强度和试件的重量损失．结果表明：掺入硅灰会略微增加混凝土早期自生收缩，而对早期干燥收缩影响不大；粉煤灰的掺入能大幅度地减小混凝土早期自生收缩，但使早期干燥收缩增加；磨细矿渣只有在掺量较多时才能明显降低早期自生收缩，却对早期干燥收缩不利；同水胶比加掺合料混凝土的早期自生收缩与抗压强度之间有很好的线性关系，早期干燥收缩与试件的水分散失率间呈近似的对数函数关系．

Characteristics of early age shrinkages development of HPC containing mineral admixtures

Autogenous shrinkage under sealed condition and total shrinkage under single-faced dry condition of concrete with different mineral admixtures were measured from 6 hours to 3 days age by a new method, which adopted one type of untouched micro-displacement sensor controlled by a programmed computer automatically. The strength development and weight loss of every concrete were measured at the same time. Results shown that the addition of silica fume could increase the autogenous shrinkage a little and almost had no effect on the drying shrinkage. Fly ash could markedly decrease the autogenous shrinkage of concrete at early age, but the drying shrinkage may be increased due to lowering concrete strength development. The autogenous shrinkage of concrete could be evidently decreased at early ages only when high replacement of finely-pulverized blast slag was used, but the drying shrinkage would be increased in the case. The relationship between autogenous shrinkage and compressive strength of the same w/b concretes with mineral admixtures could be described as a linear equation. The drying shrinkages of the same w/b concretes at early ages could be approximately expressed as a logarithmic function of the water loss ratio.