Study On The Performance Of Fly Ash Replacing Fine Aggregate Concrete

Because the rapid economic development bring about the resource consumption and environmental pollution to the environment pressure, in order to solve the effect of the sustainable development of the local economy and even the national economy long-term development of the contradiction between the urgent economic growth and environmental protection. Fly ash is used as fine aggregate in concrete mix design and construction, to improve the utilization of fly ash, avoid the phenomenon of river sand disorderly gathering, reduce the cost of concrete engineering, maintain environmental protection, economic development will be a project that is worthy of further study.In this paper, use grade II fly ash to replace fine aggregate in the concrete.making 11 kinds of C30 concrete,the rate of replacement is 0% to 50%.Test the bleeding and concrete slump of the fresh concrete under different replace rates.Through the standard curing, the compressive strength and flexural strength of concrete was tested under different replacing rates at different ages. At the same time, using the destroyed bending blocks test its compressive strength. The results show that the limit rate of replacement is 45%. At a certain dosage of admixture, the concrete slump declines with the increase replacement of fly ash.Bleeding properties of concrete have been improved under 15% replacement.lt is concluded the formula that the bleeding rate of concrete under different rates of replacement; Fly ash fine aggregate can improve the compressive and flexural strength of concrete.25% replacement rate fly ash hydration reaction efficiency is the best; above 25% replacement rate, the filling effect is remarkable. After analyzing the results of the experiment, obtain the relation between the fly ash fine aggregate concrete compressive strength and flexural strength; Also, the relation between standard compressive strength of the concrete and compressive strength measured by the destroyed bending blocks.Finally, through SEM electron microscope, analysis the different fly ash fine aggregate replacement rate of concrete material performance development characteristics. This paper providesa evaluation method thatthe large dosage of fly ash is used for application research and testing technologyin concrete.