Research Of Test Methods For Filling Ability Of Fresh Self-Compacting Concrete

Self-compacting concrete (SCC) is an innovative concrete that does not require vibration for placing and compaction, and the environmental-friend concrete also has the same engineering properties and durability as traditional vibrated concrete. The primary performance attributes of fresh self-compacting concrete are filling ability, passing ability and stability. The testing process and technology is considered the hamper that hinders the increased use of SCC. Experimental research that embeds in the workability of SCC is therefore an essential to facilitating SCC's widespread use in general construction. The thesis examines the SCC's filling ability in depth by means of experimental research and numerical simulation, and acquires the following conclusions.(1)The self compacting concrete that has good workability is produced successfully with local raw materials in HuNan province, and the relation between SCC's filling ability and its mix design is studied by experimental research by abrams cone and V-type funnel. Conclusion is founded from the experimental study: During the SCC producing process, adjusting W/C ratio and sand content by mass of aggregate can change fresh SCC's filling ability obviously, But adjusting Polycarboxylate Superplasticizer content slightly and choosing different maximal diameter of aggregates can't influence fresh SCC's filling ability visibly. The three different V-type funnels (No.1 funnel is recommended by China and United America, No.2 funnel is recommended by Japan, No.3 funnel is recommended by Europe) can test filling ability of fresh SCC, and the test results are different whose mean ratio is proportional. In addition, surface coarseness of the V-type funnel can influence the flowing time from V-type funnels.(2)Applying distinct element method(DEM), the DEM model for simulating V-type funnel flowing process of fresh SCC is established by choosing DEM model, material viscosity and friction coefficient reasonably. The flowing state, flowing angles and their tangent values inosculate the experimental results closely, and the parameters for DEM model are related nearly to materials'physical properties and rheology parameters of fresh SCC.(3)Applying artificial neural networks(ANN) theory, an ANN prediction model for time that fresh SCC flows out from V-type funnel is established, and the conclusions founded from the model are accordant to the experimental results. Furthermore, Choosing the reasonable BP neural networks and training functions is important to decreasing the training epcchs and nodes of the ANN model's hidden layer, and can optimize the ANN model.(4)Applying analytic hierarchy Process(AHP), An simple and convenient AHP model for evaluating the fresh SCC's workability which can be manipulated easily is established.