Experimental Research On Mechanics And Durability Of Fly Ash Lightweight Aggregate Concrete

In this experiment,using natural pumice from Xilinhot as lightweight aggregate and mix with a certain percentage of fly ash to replace cement to prepare concrete and study the effect of different fly ash dosage on the compressive strength of lightweight aggregate. Then, prepare lightweight aggregate concrete on the basis of the best dosage of fly ash, do sulfate attack test.About the research on compressive strength of concrete, there are six dosage of fly ash respectively0,15%,20%,30%,45%,60%and five curing period, respectively3d,7d,14d,21d,28d. And analyze from a microscopic point of view on the appropriate dosage of fly ash lightweight aggregate concrete under standard28d conservation. For the test on sulfate attack resistance under the best dosage of fly ash lightweight aggregate, mainly through wet and dry cycle test to achieve. The concentration of sodium sulfate is3%,5%,7%in the experiment.The test on compressive strength and resistance to sulfate corrosion of fly ash lightweight aggregate concrete show that the failure process of fly ash lightweight aggregate concrete is always the first overall structural damage eventually lead to destruction of lightweight aggregate concrete. Through the study on the compressive strength of the corresponding age of lightweight aggregate concrete found that fly ash dosage of15%to30%can significantly improve the compressive strength of lightweight aggregate concrete, and this is confirmed from SEM images. Through the damage form of lightweight aggregate concrete in different dosage of fly ash found that their destruction forms are similarities. Through the study on mass changes, compressive strength changes and ultrasonic velocity changes under the best dosage of fly ash in the lightweight aggregate concrete found that when the concentration of sodium sulfate solution is7%the erosion is the fastest, followed by5%,3%is the slowest. Through the study on ultrasonic velocity and compressive strength of concrete after wet and dry cycles found that the relationship between the two are exponential function relationship. Through the research on stress-strain curves change of concrete specimens after wet and dry cycles found that three conditions of stress-strain curves are similar and the higher the concentration of sodium sulfate solution, the larger deformation of the specimens after erosion, the plasticity are more obvious. Through the analysis of the relative stress-strain curve of the erosion specimens in7%sodium sulfate solution found that the cubic function can be used as the ascending and descending segment of the relative stress-strain curve matched curve.