Experimental Study On Anti-Carbonation Properties Of High Volume Fly Ash Concrete

The concrete is the most comprehensive construction material being used in the construction.In modern engineering ,the concrete should not only meet the requirement of the design of the engineering mechanics,but also meet the demand of the durability。Use the fly ash instead of a part of cements, fly ash also is made panel wall and brick as the main material. Not only the project cost cut down, but also improved the quality of concrete.The carbonation resistance of concrete is the most important part of the concrete durability .The effect of the fly ash on the carbonation resistance of concrete has met many problems at present。Supported by the country"11th Five-Year Plan"to support science and technology project,this paper has studied on the carbonation resistance of high volume fly ash concrete.This test apply methods of accelerated carbonation,study of the quality of carbonation between the different water to binder ratio,the different calendar age and the different air entraining agent when the replacement of cement by fly ash was 0%,20%,40%,60%,80%.The main results obtained are as follows:(1)The fly ash addition and the water to binder ratio is the most important facts of the high volume fly ash concrete,the water to binder ratio is the critical factor.The carbonation depth of the 0.35 water to binder ratio is lower than the 0.4 water to binder ratio whatever the calendar age when the replacement of cement by fly ash was 60%,and the amplification of carbonation depth was slow down of the 0.35 water to binder ratio,practical requirement of the project need.(2)The quality of construction of the high volume fly ash concrete should be practical requirement of the project need when the water to binder ratio is lower than 0.4;The maximum of fly ash reachd 80%,few are covered in modern China .(3)The carbonation depth of the high volume fly ash concrete is increased with the increasing time.study on the experimental data, the power exponent Curve-fitting Model should be used to forecast the carbonation depth.(4)The early strength of the fly ash concrete is lower,but the growth rate of the strength is faster later . this is important for lengthensservice life.thought strength analysis,get the conclusion that when the parameter is time ,could use the Curve-fitting Model. (5)thought the Comparison and analyses of these models with the experimental data,found that the significance of each models is different because of the complicated influence factor,so the computing result is discrepancy.so when use these model ,should based on the practice。And get the 28d predictor formula of the high volume fly ash concrete by the software of matlab。...