Experimental Study On Low-strength Self-compacting Concrete And Its Shrinkage

With the increasing development of the modern civil engineering, the workability of ordinary concrete and durability have been unable to meet the demand of construction. How to effectively improve the workability of concrete and durability, and expand the use of concrete to extend the service life of concrete, experts and scholars at home and abroad have become the focus of research.Self-Compacting Concrete is one of the new High-Performance Concrete based on the construction of a high for the outstanding feature.Self-Compacting Concrete is obtained through selectioning the aggregate, cement materials, additives, and so on and mix designing. The mixing of SCC had adequacy of plastic viscosity, and the particles of the aggregate can suspension in cementitious material slurry without segregation and bleeding.The mixing can be reinforced through the gap and fully fill all the gaps without no vibration or do not have the basic conditions so that forming dense and uniform concrete.Compared with ordinary concrete, many of the use of High-Performance Self-Compacting concrete projects in the performance of contraction also unsatisfactory. In order to meet liquidity requirements and high stability, SCC tend to demand high cementitious material usage and water reducer volume, low water-cement ratio, and low aggregate level. All these factors have increased the contraction value of SCC.In this paper, using local materials, according to fixed volume of sand and gravel law preliminary mix for Self-Compacting Concrete (C20, C25, C30)is determined. A conclusion, which is that influence different varieties and volume of admixture to fresh concrete workability and different volume of fly ash to early strength is made through using single-factor testing method and regarding slump,slump flow, T50, 7d and 28d strength as feedback indexs, and making range analysis to experimental results. At last,the experiment successfully obtains low-strength SCC with high liquidity and no vibration,which has the characters of slup between 255mm～270mm,slup flow between 550mm～700mm, T50 between 5s～25s and enough 28d strength.At the same time in this paper, experimental study are done on low-intensity SCC shrinkage characteristics and the contraction of SCC compensation using expanders and FBC ashes. It is also studied the impaction on expansion admixture for workability for SCC mixing, the impact of hardening concrete strength and reasonable volume of compensation admixture to meet the demands; preliminary feasibility study is done whether FBC ashes can be a kind of SCC admixture by experimental study the impaction on workability for SCC mixing and strength of hardening concrete.