冻融循环作用对PP-ECC劣化行为研究  

Study on the deterioration behavior of freeze-thaw cycle on PP-ECC

作　　者：左龙飞 杨宗驰 蔡畅 刘梦辉 刘耕园 李福海[1] 吴昊南 ZUO Longfei;YANG Zongchi;CAI Chang;LIU Menghui;LIU Gengyuan;LI Fuhai;WU Haonan(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031

出　　处：《混凝土》2024年第6期30-34,42,共6页Concrete

基　　金：国家重点研发计划课题(2021YFB2600900);四川省自然科学基金(2023NSFSC0025,2021YJ0545,2022NSFSC1095);四川省工程研究中心重点项目(GF2022ZD006)。

摘　　要：针对冻融循环对聚丙烯纤维工程水泥基复合材料(PP-ECC)性能的影响,以质量损失、相对动弹性模量、抗压和抗拉强度等指标对其冻融劣化进行表征,利用试验数据建立冻融环境下PP-ECC材料各项性能的劣化规律,结合扫描电子显微镜(SEM)和压汞仪(MIP)从微观角度去分析PP-ECC试件冻融破坏机理。结果表明:冻融损伤是一个由表及里、循序渐进的过程。冻融循环作用下PP-ECC材料的轴心抗压强度、极限压缩应变与冻融循环次数近似呈线性相关,而相对动弹性模量、劈裂抗拉强度、开裂拉伸性能、极限拉伸性能的退化规律均为二次曲线下降。通过SEM和MIP试验观察到随冻融循环的增加,试样内部出现大量孔洞及微裂缝,裂缝不断发展延伸最终呈网状分布,平均孔径持续增加,有害孔和多害孔开始增多,结构愈加疏松。Aiming at the influence of freeze-thaw cycle on the performance of polypropylene fiber engineering cement based composites(PP-ECC),the freeze-thaw deterioration was characterized by indicators such as mass loss,relative dynamic elastic modulus,compressive resistance and tensile strength.Then used the test data to establish the deterioration rules of the properties of PP-ECC materials under freezing,and analyzed the freeze-thaw destruction mechanism of PP-ECC specimens from a microscopic point of view in combination with scanning electron microscope(SEM)and mercury intrusion porosimetry(MIP).The results show that freeze-thaw damage is a gradual process.The axial compressive strength and ultimate compressive strain of PP-ECC materials are linear relevant with the times of freeze-thaw cycles,but in this cycle,the degradation law of relative dynamic elastic modulus,splitting tensile strength,cracking tensile performance and ultimate tensile performance are the quadratic curve decrease.It observed the phenomenon in the SEM and MIP tests that with the increase of freeze-thaw cycles,a large number of holes and microcracks appear inside of the sample,the cracks continue to develop and extend and eventually show a network distribution,the average aperture continue to increase,harmful pores and more harmful pores begin to increase,and the structure become more loose.

关 键 词：聚丙烯纤维工程水泥基复合材料 冻融循环 力学性能 抗冻性 微观结构分析 

分 类 号：TU528.01[建筑科学—建筑技术科学]