压应力下的聚丙烯纤维混凝土抗冻性能试验研究

Experimental Study on Frost Resistance of Polypropylene Fiber Concrete under Compressive Stress

为研究混凝土抗冻性能的影响规律,基于改进的应力加载装置,设计了不同压应力比下的纤维混凝土试件和普通混凝土试件,通过冻融循环试验,结果表明:在压应力比取0~0.2范围时,应力压缩了混凝土结构内部孔隙、气泡,降低了水结冰形成的膨胀压力,结构的冻融破坏得到抑制,混凝土抗冻性增强;压应力比大于0.6时,混凝土基本处于塑性阶段,冻融破坏进程加速进行,混凝土在外部压应力以及内部膨胀与渗透等压力的综合作用下劣化较快,降低了混凝土的抗冻性;掺加适量的纤维以及施加适当的压应力,有利于促进混凝土抗冻性能的提升。

In order to study the influence law of frost resistance of concrete,based on the improved stress loading device,fiber concrete specimens and ordinary concrete specimens with different compression stress ratios are designed.Through the freeze-thaw cycle test,the results show that when the compression stress ratio is within the range of 0~0.2,the stress compresses the pores and bubbles in the concrete structure,reduces the expansion pressure formed by water icing,and suppresses the freeze-thaw damage of the structure,therefore the frost resistance of concrete is enhanced.When the compressive stress ratio is greater than 0.6,the concrete is basically in the plastic stage,the freezing and thawing damage process is accelerated,and the concrete deteriorates rapidly under the combined action of external compressive stress and internal expansion and seepage,which reduces the frost resistance of the concrete.Adding proper amount of fiber and applying appropriate compressive stress can promote the improvement of frost resistance of concrete.