Optimization Of High Volume Fly Ash Concrete Technology

China is now in the peak period of large-scale infrastructure construchtion, needing a huge amount ofconcrete. To2010, China’s cement production capacity is near19million tons, which is mainly for theproduction of concrete, accounting for more than55%of world production. To improve the service life ofconcrete structures, rational use of resources, protecting the environment, developing and using greenconcrete technology have important strategic significance. This paper focuses on performance optimizationof high volume fly ash concrete in which fly ash to total cementitious material ratios are45%,50%,55%and60%，and the effect of expansive agent and lime and gypsum content on the properties of highvolume fly ash concrete are studied. The main research focused on strength development law,anti-carbonation properties and resistance to chloride ion penetration performance. And by scanningelectron microscopy (SEM) micro-test, microstructure of high volume fly ash concrete and micro-structuralwatershed features of cement-fly ash-expansive agent and cement-fly ash-lime-gypsum cementitioussystem were analyzed at different age period. In addition, Engineering applications and economic value ofhigh volume fly ash concrete are objectively valued through the experimental resultsThe results show that strength of the high volume fly ash concrete with expansive agent is greataffected by the natural environment temperature and humidity of early time. Compared withnon-expansive agent concrete, appropriate amout of expanders help improve the early strength of concrete.The concrete strength with different content of fly ash develeped steadily when the HCSA expans iveagent dosage is6%,so6%are considered the appropriate addition amount.10%HCSA expansion agentdosage can cause excessive expansion and is detrimental to structural stability and strength,and is notdesirable. in the actual project. Adding appropriate amount of of lime and gypsum in concrete can greatlyimprove the compressive strength, and the concrete sttrength development laws are the samilar withconcrete adding6%HCSA expansive agent.Ability of anti-carbonation of concrete decreased when the fly ash content improved. Adding6%expansive agent or lime, gypsum into high volume fly ash concrete have little effect on natural carbonationdepth, but can improve the ability of resistsing forced carbonation. Long curing time can improve theproperties of carbonation, resistance to chloride ion penetration and resistance to Freezing and thawing.Ater28d curing conditions, the ability of carbonation are improved significantly. Comprehensive examinationof curing system and climatic conditions are favorable to ensure strength and durability of concrete in theresearch and application of high volume fly ashThe micro-structure of high volume fly ash concrete adding HCSA expansive agent or lime, gypsumwas dense, and had more hydration products by SEM test, indicating HCSA expansive agent or lime,gypsum can promoted hydration and second hydration,The materials cost analysis showed that the economic benefits of high volume fly ash concrete percubic are significant. Even if the addition amount of fly ash is about60%, long-age strength of concrete canreach C30, which can meet the requirement of engineering appliction...