The mechanical properties of early‐age fly ash (FA) concrete was experimentally studied. The splitting tensile strength and compressive strength under different curing ages, temperatures, cooling methods and FA contents were analyzed. The experimental results showed that the splitting tensile strength of concrete increased proportionally with temperature in the early stage and decreased as the temperature further increased. Compared to the concrete with FA content of 10% and 30%, the compressive strength of concrete with FA content of 20% was found to be highest at the age of 90d. The strength of the specimens under water cooling was comparatively lower than that under air cooling. The compressive strength of FA concrete heated to 150°C was greater than that of the unheated concrete. The compressive strength of FA concrete heated to 550°C was lower than that of concrete without treatment at high temperature. After high temperature exposure at the age of 90d, the compressive strength of the specimen was higher than that of the specimens at the ages of 7d, 14d and 28d. The microstructures of the specimens aged 90 days were measured by the SEM method before and after being exposed to high temperatures.

中文翻译：

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养护龄期对高温下粉煤灰混凝土力学性能的影响

对早期粉煤灰（FA）混凝土的力学性能进行了实验研究。分析了不同固化时间，温度，冷却方式和FA含量下的劈裂抗拉强度和抗压强度。试验结果表明，混凝土的劈裂抗拉强度在初期与温度成正比，随温度的升高而减小。与FA含量为10％和30％的混凝土相比，FA含量为20％的混凝土的抗压强度在90d时效最高。在水冷条件下，试样的强度比在空冷条件下的强度要低。加热到150°C的FA混凝土的抗压强度大于未加热的混凝土。加热到550°C的FA混凝土的抗压强度低于未经高温处理的混凝土。90d高温暴露后，试样的抗压强度高于7d，14d和28d时的抗压强度。在暴露于高温之前和之后，通过SEM方法测量了90天的样品的显微组织。