冻融循环作用下聚丙烯纤维混凝土的力学性能

Mechanical property of polypropylene fiber reinforced concrete under freezing-thawing cycle effect

通过4组不同配合比聚丙烯纤维混凝土的快速冻融循环试验,测得了不同冻融循环次数后混凝土的抗压强度、纵波波速与动弹性模量,研究了冻融循环作用下不同配合比聚丙烯纤维混凝土的力学性能与损伤量特征,分析了材料性质、材料配合比与冻融循环次数对力学性能的影响。分析结果表明:冻融循环200次后,未掺加引气剂的C30聚丙烯纤维混凝土、掺加引气剂的C30聚丙烯纤维混凝土、未掺加引气剂的C40聚丙烯纤维混凝土、掺加引气剂的C40聚丙烯纤维混凝土的抗压强度损失率分别为46.53%、49.05%、34.56%、37.64%;冻融循环300次后,4组聚丙烯纤维混凝土纵波波速分别降低了8.42%、6.48%、16.72%、11.68%,动弹性模量分别降低了46.54%、35.72%、54.41%、53.72%;冻融循环150次后,C30和C40聚丙烯纤维混凝土损伤量迅速增长,且C40聚丙烯纤维混凝土损伤量高于C30聚丙烯纤维混凝土;在相同的冻融次数下,未掺加引气剂的C40聚丙烯纤维混凝土的损伤量最大;抗冻性能的改善效果从大到小依次为掺加引气剂C30聚丙烯纤维混凝土、未掺加引气剂C30聚丙烯纤维混凝土、掺加引气剂C40聚丙烯纤维混凝土、未掺加引气剂C40聚丙烯纤维混凝土。

Through fast freezing-thawing cycle test on four groups of polypropylene fiber reinforced concretes with different mix proportions, the compressive strength, longitudinal wave velocity and dynamic elastic modulus of concrete after different times of freezing-thawing cycles were obtained, the mechanical property and damage amount characteristics of polypropylene fiber reinforced concrete under freezing-thawing cycle effect were studied, and the effects of material property, material mix proportion and times of freezing-thawing cycles on the mechanical property were analyzed. Analysis result shows that after 200 times of freezing-thawing cycles, the compressive strength loss rates of C30 polypropylene fiber reinforced concrete without air entraining agent, C30 polypropylene fiber reinforced concrete with air entraining agent, C40 polypropylene fiber reinforced concrete without air entraining agent and C40 polypropylene fiber reinforced concrete with air entraining agent are 46. 53%, 49.05%, 34.56% and 37. 64% respectively. After 300 times of freezingthawing cycles, the longitudinal wave velocities of four groups of polypropylene fiber reinforced concretes decrease by 8.42%, 6.48%, 16. 72% and 11.68% respectively, and the dynamic elastic moduli decrease by 46.54%, 35.72%, 54. 41% and 53. 72% respectively. After 150 times of freezing-thawing cycles, the damage amounts of C30 and CA0 polypropylene fiber reinforced concrete increase rapidly, and the damage amount of C40 polypropylene fiber reinforced concrete is bigger than that of C30 polypropylene fiber reinforced concrete. Under the same times of freezing-thawing cycles, the damage amount of CA0 polypropylene fiber reinforced concrete without air entraining agent is biggest. The improving effects on frost resistance property from big to small are C30 polypropylene fiber reinforced concrete with air entraining agent, C30 polypropylene fiber reinforced concrete without air entraining agent, CA0 polypropylene fiber reinforced concrete with air entraining agent, C40 polypropylene fiber reinforced concrete without air entraining agent. 6 tabs, 7 figs, 28 refs.