In Low-strength Self-compacting Concrete Mix Parameters To Optimize The Study

Starting with the analysis of the relations between the composition materials and the workability, strength and shrinkage of the self-compacting concrete, the thesis studied the effect of the water to binder ratio, mineral admixture content, aggregate volume content etc. on the workability, strength and shrinkage performance of medium strength self-compacting concrete, analysed the mutual relationship between the concrete shrinkage and the free water loss rate, hydration degree of the corresponding cement paste. On the basis of the above research, the mixing paremeters of medium strength self-compacting concrete were optimumed.The research results show that:(1) The workability and shrinkage is the key of mixing medium strength self-compacting concrete.(2) The effect of the water to binder ratio, fly ash and aggregate volume content on the filling ability, passing ability and stability of self-compacting concrete is significant.(3) There are close correlations between the 28-day compressive strength and the mixing parameters, so the empirical equation was established.(4) The shrinkage value of self-compacting concrete increases with the increasing water to binder ratio. When the fly ash content increases, the shrinkage value reduces. The free water loss rate increases with the increasing age and water to binder ratio. Meanwhile, the free water loss rate increases when the fly ash content increases. The shrinkage value increase with the free water loss rate increases, and the obvious correlation is observed between them.(5)The shrinkage value of self-compacting concrete increases with the chemical combined water of the corresponding paste increases. Under the same conditions, when the fly ash content increases, the chemical combined water of cement paste reduces and the shrinkage value decreases.(6) Based on the demands of the workability, strength and volume stabilization of medium strength self-compacting concrete, the proper coarse aggregate volume content should be the range of 0.29～0.35, the proper fine aggregate volume content should be the range of 0.28～0.35, the water to binder ratio should be less than 0.42.