Research On High Performance Self Compacting Concrete

With the rapid development of construction industry, all kinds of complex structures such as high-rise building structure, large span structure and so on, this paper has brought the unprecedented opportunity and challenge. Ordinary concrete has become increasingly unable to meet the needs of modern construction, High performance self compacting concrete (HPSCC) has the advantages of free vibration, easy construction and high pumping. It has become a hot research topic in the field of concrete. This paper is based on the SCC performance characteristics and the research results, the key materials and the properties of the material.The dissertation studies the effect of HPSCC on the workability and mechanical properties of concrete, and analyzes the effect of expansion agent, curing condition, and admixture on the shrinkage of concrete.The effects of agent composition on workability and strength of self compacting concrete was studied through orthogonal experiment. The optimal combination of admixture was determined with the 28d strength as the index. The influence of water reducer on the cement paste was studied by means of the rheological property of cement paste, and the optimal dosage range of the water reducer was determined.The effects of the main factors, such as the amount of water reducer, water content, water content, sand ratio, aggregate gradation, and the total amount of cementitious materials, on the performance of concrete are studied, Studies have shown that by different functional poly carboxylic acid reducing agent optimization of combination, water reducing agent has good comprehensive properties, water reducing agent poor compatibility, to raw material is too sensitive to be a good solution, but more than a certain critical point, mixture prone to bleeding and segregation phenomena, and the mechanical properties decreased. Under the condition of fixed water binder ratio, water consumption increased, strength increases, but water consumption reaches a certain amount, down 28d compressive strength; increasing sand ratio, liquidity can improve the mixture, but beyond a certain point, due to increase of the surface area and reduced HPSCC variation, strength; through different size gravel admixture, coarse aggregate voids can be significantly reduced, thereby improving the workability and mechanical properties of HPSCC; water is fixed, the amount of cementitious materials have improved, workability and mechanical property of HPSCC can improve the cementing material, adding excess will lead to HPSCC the viscosity increases, is not conducive to the construction and control of hydration heat.The influence of fly ash and slag powder on the performance of concrete is analyzed by the working performance and mechanical properties. Results show that the addition of fly ash can improve the fluidity of concrete mixture, and decreases the early strength of hpscc and content of fly ash in 10%-20% can improve the later strength of the concrete and the addition of slag powder membership lead to concrete is more prone to the phenomenon such as segregation and bleeding, and early strength of serious decline, but later strength is sustainable development trend; fly ash and slag powder admixture "stack effect", fly ash and slag powder amount is certain, the greater the amount of slag powder, concrete mixture better fluidity, compressive strength.The effects of mineral admixtures, expansive agent and curing condition on the shrinkage of HPSCC was studied in the view of the disadvantage of HPSCC shrinkage cracking. The results show that the shrinkage of concrete can be improved significantly by the addition of fly ash and the shrinkage of concrete can be improved by the addition of HPSCC, while the content of HPSCC can be improved significantly, but it is not obvious that the effect of water curing is very important to improve the shrinkage of concrete, but it is very important.