Performance Study Of High Strength Desert Sand Concrete After High Temperature

At present, the domestic and foreign scholars about the desert sand performance of high-strength concrete has a large number of experimental studies, but about the desert sand with high strength concrete after high temperature performance of the research is few and far between, so, in this paper, in order to study the water-binder ratio, fly ash content and desert sand replacement of desert sand with high strength concrete after high temperature changes of its performance, through the design of orthogonal test, to study the desert sand with high strength concrete before and after high temperature change of the change of physical characteristics, quality and the change of the desert sand with high strength concrete compressive strength. This experiment will desert sand as one of the raw materials of high strength concrete, for the desert sand with high strength concrete was applied to the actual reference and guidance for the construction project.(1) The orthogonal experiment adopts C60 high strength concrete, forming 100×100×100mm cube, and carries on the maintenance under the standard curing condition, will be completed maintenance of concrete specimens respectively at room temperature (20℃),200℃,400℃,600℃,800℃ and 900℃ six temperature of concrete under high temperature test, the heating rate control in 10℃/min, to reach the set temperature warm after two hours, then take out concrete specimen, using natural cooling and water cooling, cooling after incubation for 24h. The experimental results show that: ①. With the increase of temperature, the color of the concrete by deep gradually becomes shallow, clash by depressing to crisp, surface crack by fewer cracks, crazing to number, crude; ②. The change law of quality loss can present certain as the temperature increases quality loss will gradually increase; ③. The compressive strength of concrete after high temperature at 200℃,400℃ and 600℃ when the compressive strength can increase somewhat, even higher than that of the concrete compressive strength at room temperature, and with the increase of temperature,800℃ and 900℃ when the compressive strength gradually decreased;④.Finally it is concluded that the orthogonal experiment the optimal mixture ratio for A1B2C2.(2) On the basis of orthogonal experiment, the design content of fly ash and the desert sand replacement rate of single factor experiment, the effects on concrete performance of the single factor experiment and orthogonal experiment could be divided into (20℃), the temperature of 400℃,500℃, 600℃,700℃ and 850℃ temperature of six grades, desert sand replacement rate were 0%,20%,0%, 60%,80% and 100%, respectively, the design when the dosage of fly ash is 10% and 20% of desert sand replacement rate affect the performance of concrete. The experimental results show that:①. The change of the concrete specimens after high temperature physical characteristics and the change of the orthogonal experiment of concrete specimen physical characteristics; ②. The quality of the specimen loss also can present certain change rule, as the temperature increases quality loss will gradually increase; ③. The compressive strength of sand in the desert the replacement rate of 20% was increased, when they reach maximum compressive strength, with the increase of desert sand replacement after compressive strength gradually decreased, ultimately determine the optimal level of desert sand replacement rate of 20%.