摘要:
研究了掺纳米SiO2的钢纤维混凝土(NSFC)、 钢纤维混凝土(SFRC)和普通混凝土(NC)三种材料在不同加热温度后的抗压、 劈裂和抗折强度等力学性能, 对不同温度热处理后的微观结构进行了SEM分析, 对钢纤维与过渡区界面的相结构进行了XRD分析。结果表明: 在测试温度范围内, NSFC的抗压、 劈裂和抗折强度均高于SFRC和NC的强度, 且在400 ℃时达到最大值。在常温下, NSFC的抗压、 劈裂和抗折强度较NC分别提高27.01%、 63.28%和54.12%, 400 ℃高温热处理后比NC分别高35.09%、 84.62%和87.23%; SEM分析表明, 在钢纤维与过渡区的界面处, 致密度提高, 显微硬度提高。由于固相反应, 使界面区结构发生变化, 在钢纤维表层形成扩散渗透层(白亮层), 即化合物层, 呈锯齿状, XRD分析证明, 白亮层主要由FeSi2和复杂的水化硅酸钙组成, 从而增强了钢纤维与基体的粘结力, 提高了混凝土的高温力学性能。
Abstract:
The high temperature mechanical properties of the nano-SiO2 steel fiber reinforced concrete(NSFC), the steel fiber reinforced concrete(SFRC) and the normal concrete(NC) were investigated, such as the compressive strength, splitting tensile strength, flexural strength, and so on. SEM and XRD were used to analyze micro-structure and interfacial transition zone of steel fiber at different temperatures. The results show that the compressive strength, splitting tensile strength and flexural strength of NSFC are better than that of SFRC and NC in the test temperatures, and reach maximum at 400 ℃. Compared with NC, the compressive strength, splitting tensile strength and flexural strength of NSFC increase by 27.01%, 63.28% and 54.12%, respectively, at room temperature, and by 35.09%, 84.62% and 87.23%, respectively, at 400 ℃. SEM and XRD analysis shows that there is a permeable diffusion layer on the steel fiber surface because of solid state reaction in the interfacial transition zone of steel fiber and concrete. This permeable diffusion layer is white, bright, serrated, and mainly consists of FeSi2 and the complex hydrated calcium silicate. The compounds of this layer change the interfacial transition zone structure, enhance bonding capacity of the steel fiber and matrix, and increase the high temperature mechanical properties of concrete.
百度学术
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