自密实混凝土与老混凝土的粘结收缩试验研究

Experimental Research on Shrinkage of Adherence of Self-compacting Concrete on Old Concrete

以自密实混凝土为新混凝土材料,通过在新混凝土上的主要位置布置应变片,进行了新老混凝土粘结收缩试验研究,考察了不同粉煤灰掺量和界面处理方法对新混凝土收缩的影响.由试验结果可知,新老混凝土粘结的约束收缩分布及发展规律基本相同,靠近粘结面处的收缩很小,而在新混凝土中间顶部的收缩最大;适当的粉煤灰掺量能控制新混凝土的约束收缩;自然光滑面粘结试件在粘结面处的收缩应变较大,而新混凝土上其余各点收缩应变的变化比粗糙面粘结试件的小.采用双曲线函数拟合了最大收缩应变随时间变化的计算式,可为实际工程提供参考.

With the self-compacting concrete as new concrete, the restrained shrinkage experiment of new and old concrete is con- ducted by strain gauge in order to study the influence of concrete strength and disposed interface. The test results show that the distributing and development of restrained shrinkage of new and old concrete are basically similar for every specimens; the shrinkage is least near the interface,but most on the top; the appropriate content of fly ash can control the restrained shrinkage of new concrete; and the shrinkage strain of specimen with smooth interface is bigger than that of rough interface. The calculating formulae of restrained shrinkage of self-compacting concrete are put forward by hyperbola function in this paper.