冻融作用后混凝土力学性能的衰减规律

Degradation of mechanical properties of concrete caused by freeze-thaw action

开展了混凝土在冻融作用后各项基本力学性能衰减规律的试验研究,包括冻融作用对混凝土受压应力-应变关系、劈裂抗拉性能、抗重复荷载性能的损伤影响,并根据工程中结构构件的实际工作状态,进行了压应力与冻融循环双重因子作用下混凝土的抗冻性能及力学性能衰减规律的研究。试验现象表明:随着冻融循环次数的增多,混凝土轴心抗压强度、劈裂抗拉强度、抗重复荷载性能等力学性能指标的下降程度均逐渐加大,并根据试验结果得出了混凝土上述各项力学性能指标随冻融作用的退化规律,建立了与冻融参数相关的退化计算公式。通过试验研究还发现:混凝土在承载状态下,冻融作用对其损伤影响将加剧,混凝土承载能力的衰减幅度较单一冻融作用更显著。本文研究可为建立符合实际工程的混凝土结构抗冻耐久性设计理论提供基础资料。

A series of experimental studies of mechanical properties of concrete after freeze-thaw action have been conducted. These researches involved the damage caused by freeze-thaw action on compressive stress-strain relationship, splitting strength and mechanical behavior under repetitive load action. Moreover, according to bearing state of members in actual engineering, we also investigated the damage of frost-resisting and mechanical properties of concrete suffering from dual actions of compressive stress and freeze-thaw cycles. Experiment indicates that due to repeat freeze-thaw cycles, degradation of mechanical properties, including compression strength, splitting strength and repeated load-resistant property so on, is more serious, then degradation patterns correlated with freeze-thaw parameters of mechanical properties are found. Meanwhile a conclusion has been drawn that when bearing state of concrete is considered, the damage caused by freeze-thaw action is aggravated, and the degradation is more significant than that under single freeze-thaw action. This study may serve as a reference to establish frost-resisting durability design theory of concrete structure.