自密实混凝土收缩试验研究及收缩模型的建立

Experimental study and modeling on shrinkage of self-compacting concrete

通过试验研究自密实混凝土自生收缩、干燥收缩的发展变化规律,所考察的配合比参数包括粉煤灰掺量、粉煤灰和矿渣复掺、水胶比、胶结料用量等.基于试验结果对已有的模型进行修订,给出适合自密实混凝土的收缩模型.结果表明:随着矿渣复掺比例的增大、水胶比的下降,自密实混凝土各龄期的自生收缩显著增大,而干燥收缩则有明显减小的趋势;两种收缩都有随胶结料总量的增大而增大的趋势.配合比因素对两种收缩的影响规律并不相同,有必要进行分别研究.本文给出的模型能较好地考虑自密实混凝土的特点,与试验结果吻合良好.

Autogenous and drying shrinkage of self - compacting concrete are experimentally studied, the mixture parameters include fly ash dosage, ratio of fly ash and slag mixed dosage, water to binder ratio, total binder content et al. The existing shrinkage models about high performance concrete are e- valuated based on the test results, then models suitable for self- compacting concrete are presented. The results showed that： with the increase of slag dosage and decrease of water/cement ratio, autogenous shrinkage of self - compacting concrete has a tendency to increase, while the drying shrinkage has a tendency to decrease; but with the increase of amount of total binder, both autogenous and drying shrinkage have a tendency of increasing. It is necessary to evaluate these two kinds of shrinkage respectively. The given model can be well used to self- compacting concrete, and have a good agreement with the test results.