高温对高强高性能混凝土抗压强度影响机理研究

Study on influence mechanism of high temperature on compressive strength of high-strength and high-performance concrete

研究了300、500、800℃高温条件对高强高性能混凝土抗压强度的影响,采用XRD、热分析等方法测试了高温作用后水泥浆体和骨料的物相组成、热稳定性等微观结构,以探讨不同高温条件对高强高性能混凝土抗压强度影响的机理。结果表明,300℃高温条件下,高强高性能混凝土内部形成高温蒸养环境,促进其抗压强度提高,较105℃烘干强度提高了31.6%~42.2%;500℃和800℃高温条件下,高强高性能混凝土中水泥浆体的水化产物随温度的升高大量分解,导致混凝土的抗压强度逐渐降低,当温度达到800℃时,其抗压强度与105℃烘干强度相比下降了30.5%~35.9%。

The influence of high temperature conditions of 300℃,500℃and 800℃on the compressive strength of high-strength and high-performance concrete was studied.The microstructure of cement paste and aggregate after high-temperature,such as phase composition and thermal stability,was tested by means of XRD and thermal analysis to explore the mechanism of the influence of different high temperature conditions on the compressive strength of high-strength and high-performance concrete.The results show that the high temperature steam curing environment is formed at 300℃,which improves the compressive strength by 31.6%~42.2%compared with the drying strength at 105℃.Under the high temperature of 500℃and 800℃,the hydration products of the cement paste in the high-strength and high-performance concrete decompose with the increase of the temperature,which leads to the deterioration of the compressive strength of the concrete.When the temperature reaches 800℃,the compressive strength decrease up to 30.5%~35.9%compared with the drying strength at 105℃.