冻融循环作用下纤维混凝土动态抗压性能  

Dynamic Compressive Performance of Fiber Concrete under Action of Freeze-Thaw Cycle

作　　者：王维良 逯静洲[1] 孔政宇 王建伟 WANG Weiliang;LU Jingzhou;KONG Zhengyu;WANG Jianwei(School of Civil Engineering,Yantai University,Yantai 264005,China)

机构地区：[1]烟台大学土木工程学院,山东烟台264005

出　　处：《烟台大学学报（自然科学与工程版）》2024年第1期87-92,共6页Journal of Yantai University(Natural Science and Engineering Edition)

基　　金：国家自然科学基金资助项目(51978596)。

摘　　要：为研究冻区混凝土动态抗压性能,对不同掺料的混凝土试件进行了先冻融循环后单轴动态抗压试验。研究了三组混凝土(PVA纤维、纳米SiO_(2)和PVA-纳米SiO_(2))在不同应变速率(10-5s^(-1)、10-4s^(-1)和10^(-3)s^(-1))下的强度变化率、应变损失率,分析得到三种混凝土动态抗压性能的优劣关系。通过试件切片的SEM电镜扫描试验,研究了掺料改善混凝土性能的微观作用机理。研究结果表明:单掺PVA纤维或纳米SiO2(P组、S组),对于混凝土受冻后的动态抗压性能无明显改善。双掺(SP组)时,纳米SiO2与水化产物Ca(OH)2反应生成的C-S-H凝胶填充了混凝土的孔隙和ITZ,增强了混凝土的密实性,为受冻后混凝土中PVA纤维更完整地发挥桥连作用提供了条件。冻融循环100次后的SP组混凝土在应变速率从10^(-4)s^(-1)到10^(-3)s^(-1)的情况下,其相较于P组、S组的强度提高约10%,PVA纤维和纳米SiO2的协同作用使混凝土受冻后的动态抗压性能改善明显。In order to study the dynamic compressive performance of concrete in frozen areas,an uniaxial dynamic compressive test is carried out on concrete specimens with different admixtures after freeze-thaw cycles.The loss ra-tio of strength and strain of the three groups of concrete(PVA fiber,nano-SiO_(2)and PVA-nano-SiO_(2))under differ-ent strain rates(10^(-5)s^(-1),10^(-4)s^(-1) and 10^(-3)s^(-1))are studied to evaluate the relationship of excellence and imper-fection of their dynamic compressive performance.The microscopic mechanism of admixture to improve the perform-ance of concrete is studied by SEM scanning test.The results show that,for concrete mixed with PVA fiber or nano-SiO_(2) alone(Group P or Group S),the admixture has no significant effect on the dynamic compression performance of concrete after freeze-thaw cycles.When double mixed with PVA fiber and nano-SiO_(2)(Group SP),the C-S-H gel formed by the reaction of nano-SiO_(2) and hydration product Ca(OH)_(2) fills the pores and ITZ of concrete,enhances the compactness of concrete,and provides conditions for the more complete bridging effect of PVA fibers in concrete after freezing.After 100 freeze-thaw cycles,the strength of concrete in SP group is about 10% higher than that in P group and S group at the strain rate from 10^(-4)s^(-1) to 10^(-3)s^(-1).The synergistic effect of PVA fiber and nano-SiO_(2) improves the dynamic compressive performance of concrete after freezing.

关 键 词：纤维混凝土 冻融循环 应变速率 微观机理 

分 类 号：TU528[建筑科学—建筑技术科学]