C60高性能混凝土高温蒸汽压力测试及SEM微观分析
发布时间：2018-10-10 18:36
【摘要】：高性能混凝土具有比普通混凝土更优越的性能,但是在火灾作用下,内部致密的结构以及较低的渗透率使其更易发生爆裂,而蒸汽压是引起高性能混凝土爆裂的主要原因之一。但由于蒸汽压力试验比较复杂,目前可供参考的试验数据较少。探索高性能混凝土高温下的蒸汽压力以及微结构变化,为蒸汽压力理论提供试验依据,对抑制高性能混凝土高温爆裂具有重要意义。本文依托国家自然科学基金(51478290),对不掺纤维与掺聚丙烯纤维C60高性能混凝土高温蒸汽压力及微结构变化进行试验研究,主要内容如下:一、通过对不同温度作用后高性能混凝土的劈裂抗拉强度的测试,对劈裂抗拉强度损失情况与温度的变化规律进行研究,表明高性能混凝土劈裂抗拉强度随着温度的升高呈下降趋势,400℃之前聚丙烯纤维混凝土劈裂抗拉强度高于不掺纤维混凝土劈裂抗拉强度,500℃与600℃分别为不掺纤维与掺纤维试件的阈值温度,劈裂抗拉强度损失率分别为57.88%与63.71%。二、对高温电阻炉加热下的不加钢筋高性能混凝土小板(不掺纤维与掺0.1%、0.2%、0.3%聚丙烯纤维),以及加钢筋的高性能混凝土小板(不掺纤维与掺0.2%聚丙烯纤维)的内部不同测点的蒸汽压力随时间以及测点温度的变化规律进行研究,表明掺聚丙烯纤维可以显著降低蒸汽压力,且0.2%为聚丙烯纤维最佳掺量。三、对明火与荷载耦合下的加钢筋的高性能混凝土大板(不掺纤维与掺0.2%聚丙烯纤维)内部不同测点位置的蒸汽压力随时间以及测点温度的变化规律进行研究,表明在明火与荷载耦合下,掺入聚丙烯纤维同样抑制了混凝土内部蒸汽压力,且50 mm测点处蒸汽压力值较大。四、对高温电阻炉、明火与荷载耦合下同一测点处的蒸汽压力进行对比,表明在明火与荷载耦合下蒸汽压力增大,聚丙烯纤维对蒸汽压力抑制作用降低。并利用薄壁球理论,将蒸汽压力与劈裂抗拉强度建立了联系,计算得出了不掺纤维试件可能出现的爆裂位置,验证了掺聚丙烯纤维试件未出现爆裂的事实。五、探讨温度对高性能混凝土内部微观结构的影响。利用扫描电镜设备对不掺纤维与掺0.2%聚丙烯纤维混凝土不同温度下的浆体、界面过渡区、孔隙结构以及高温后的聚丙烯纤维通道的微观图像进行了观察与定性分析,表明常温与155℃下高性能混凝土较为密实,300℃与500℃后劣化严重;利用IPP软件进行定量分析,表明高性能混凝土内部孔隙面积比呈先降低再增加的趋势,300℃后聚丙烯纤维试件孔隙面积比低于不掺纤维试件孔隙面积比;并将不同温度下的孔隙面积比与蒸汽压力进行了曲线拟合。本文旨在研究温度对高性能混凝土蒸汽压力与微观结构的影响,为解释高性能混凝土爆裂的蒸汽压力理论及聚丙烯纤维抑制高温爆裂的研究提供依据。
[Abstract]:High performance concrete (HPC) has better performance than ordinary concrete, but under the action of fire, the internal compact structure and low permeability make it more prone to burst, and steam pressure is one of the main causes of high performance concrete bursting. However, due to the complexity of steam pressure test, there are few experimental data available for reference at present. To explore the steam pressure and microstructure change of high performance concrete at high temperature provides experimental basis for steam pressure theory and is of great significance to restrain high temperature crack of high performance concrete. Based on the National Natural Science Foundation (51478290), this paper studies the high temperature steam pressure and microstructure change of high performance concrete without fiber and polypropylene fiber C60. The main contents are as follows: 1. By testing the splitting tensile strength of high performance concrete under different temperature, the loss of splitting tensile strength and the variation of temperature are studied. The results show that the splitting tensile strength of high performance concrete decreases with the increase of temperature. The splitting tensile strength of polypropylene fiber reinforced concrete is higher than that of non-doped fiber concrete before 400 鈩，
本文编号：2262822
[Abstract]:High performance concrete (HPC) has better performance than ordinary concrete, but under the action of fire, the internal compact structure and low permeability make it more prone to burst, and steam pressure is one of the main causes of high performance concrete bursting. However, due to the complexity of steam pressure test, there are few experimental data available for reference at present. To explore the steam pressure and microstructure change of high performance concrete at high temperature provides experimental basis for steam pressure theory and is of great significance to restrain high temperature crack of high performance concrete. Based on the National Natural Science Foundation (51478290), this paper studies the high temperature steam pressure and microstructure change of high performance concrete without fiber and polypropylene fiber C60. The main contents are as follows: 1. By testing the splitting tensile strength of high performance concrete under different temperature, the loss of splitting tensile strength and the variation of temperature are studied. The results show that the splitting tensile strength of high performance concrete decreases with the increase of temperature. The splitting tensile strength of polypropylene fiber reinforced concrete is higher than that of non-doped fiber concrete before 400 鈩，
本文编号：2262822
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