喷水冷却对聚丙烯纤维混凝土高温后力学性能的影响

Effect of Water Spraying on Post-High-Temperature Mechanical Properties of Polypropylene Fiber Concrete

通过进行高温后不同冷却条件下(自然冷却和喷水冷却)聚丙烯纤维混凝土与普通混凝土的力学试验,分析了温度和冷却方式对聚丙烯纤维混凝土的质量损失、单轴抗压强度、峰值应变、杨氏模量和显微结构等性能的影响.试验结果表明,随着温度的升高,混凝土的弹性模量与抗压强度都呈下降趋势.聚丙烯纤维混凝土在经历高温后内部纤维熔化,留下大量空隙,使得混凝土高温后的力学性能进一步恶化.通过显微镜观察到,喷水冷却下的混凝土试件中产生大量的裂缝,内部结构更加疏松.此外,通过对试验数据的统计分析,建立了在不同冷却条件下,聚丙烯纤维混凝土的相对抗压强度和杨氏模量随温度变化的关系式.

By conducting the experimental tests on polypropylene fiber reinforced concrete and plain concrete subjected to different heating temperature and cooling conditions（natural cooling and water cooling）, the mechanical properties including mass loss, uniaxial compressive strength, peak strain, Young＇s modulus, and microstructure were analyzed. The results show that the modulus of elasticity and the compressive strength of concrete tend to decrease with an increase in temperature. After experiencing high temperature, the internal fiber of polypropylene fiber reinforced concrete melted and a large number of voids emerged, which deteriorates the mechanical properties of concrete. With the help of microscope, it was found that substantial large cracks were generated inside the concrete after the process of water cooling, which results in a looser internal structure. Through statistical analysis of experimental data, relation formulas of polypropylene fiber concrete relative compressive strength, Young＇s modulus and high temperatures were set up under the different cooling conditions.