| Self-compacting concrete is a concrete that can flow freely under its self-weight withoutvibration during the placing process and flow through the gaps of reinforcement filling up theformwork. While it is cohesive enough to be handled without segregation or bleeding. FreshSCC is homogeneous and hardened SCC has excellent mechanical performance and durability.There are some complex structures and dense reinforcement in important parts of nuclearpower project, ordinary concrete is difficult to vibrate and compact, so SCC is considered tobe used in nuclear power project. Generally speaking, in order to achieve good workability,the cementitious materials content of SCC is high. The shrinkage and temperature rise of SCCwith high cementitious materials content is high, which will influence volumetric stability anddurability. Depending on National science-technology plan―Research on the key technologyof preparation and application of nuclear power self-compacting concrete‖, this study is toreduce the content of cementitious materials through following work. And SCC with lowcementitious materials content which has well workability and durability is manufactured.The research significances in the thesis are described in detail as follows:Through the test, the law that material composition influence workability and rheologicalproperty of paste and mortar of SCC can be obtained. The saturation dosage ofsuperplasticizer is1.1%, the optimal dosage of fly ash is30%, the optimal dosage of groundslag is15%, the optimal dosage of silicon fume is3%, the best water cement ratio is0.31～0.33, and sand cement ratio is1.8.According to the characteristics of actual materials, a new method was presented todesign SCC based on the distraction model of aggregate skeleton: fine aggregate filling thevoid of coarse aggregate and paste filling void of aggregate. There are three parameters in thenew design method: the thickness of coating layer, the surface area of aggregate and the voidratio of aggregete. The aggregate content of SCC can be calculated according to differentthickness of coating layer, surface area of aggregate and the void ratio of aggregate.According to the new design method, the law that thickness of paste coating layer andthickness of mortar coating layer influence the workability and rheological property has beenclarified. The test results indicate: along with the thickness of paste coating layer and mortarcoating layer increase, the slump flow of SCCs increase, the time of T50decrease, the heightfilled U-type increase, the passing time of V-shaped funnel decrease. Along with thethickness of paste coating layer increases, the plastic viscosity and yield stress of SCCdecrease. Along with the thickness of mortar coating layer increases, the plastic viscosity increases, the yield stress decreases. Through the test, the best thickness of mortar coatinglayer is5.5～6.1mm, the best paste coating layer is40～45μm.The cementitious materials content of1m~3SCC can reduce to470kg. The workabilityof self-compacting concrete met the requirement of CECS203:2006. The properties ofhardened SCC is close to ordinary concrete of Yangjiang nuclear power engineering. |
