不同强度等级混凝土对抗冻性能的影响

Influence of concrete with different strength grades on frost resistance

为评估北方公路用混凝土长期处于低温冻融环境中的安全性和耐久性。对不同强度等级(C30、C40、C50、C60)的混凝土试件开展快速冻融试验,通过测量冻融循环后的相对动弹性模量、质量损失率、抗压强度损失率,分析了不同强度等级混凝土试件抗冻性能。试验结果表明,随着冻融循环次数的增加,不同强度等级试件破坏程度均呈现逐渐加大趋势;试件强度等级越低,冻融循环后的内部结构越疏松,微裂缝数量越多,孔隙结构越差;随着强度等级的增加,试件孔隙率、质量损失率和抗压强度损失率均呈现降低特征,相对动弹性模量增加。

To evaluate the safety and durability of concrete used in highway in northern China under a long-term low temperature freeze-thaw environment,the rapid freeze-thaw tests were carried out for concrete specimens with different strength grades(C30,C40,C50,C60).The frost resistance of concrete specimens with different strength grades were analyzed based on the measure values of relative dynamic elastic modulus,mass loss rate and compressive strength loss rate after the freeze-thaw cycle.The test results show that the damage degree of the specimens with different strength grades increases gradually with the increase of the number of freeze-thaw cycles.The lower the strength grade of the specimen,the looser the internal structure after the freeze-thaw cycles,which results in more microcracks and the worse pore structure.With the increase of the strength grade,the porosity,mass loss rate and compressive strength loss rate of specimens are both reduced,while,the relative dynamic elastic modulus increases.