冻融循环作用下饱水砂浆孔结构的演变规律  

Pore Structure Evolution of Water-Saturated Mortar Under Freeze-Thaw Cycles

作　　者：邢秉元 程鹏宇 唐继朋[3] 谢恩慧 曾强 周春圣[2] XING Bingyuan;CHENG Pengyu;TANG Jipeng;XIE Enhui;ZENG Qiang;ZHOU Chunsheng(Economic Technology Research Institute of State Grid Tianjin Electric Power Company,Tianjin 300171,China;School of Civil Engineering,Harbin Institute of Technology,Harbin 150090,China;State Grid Tianjin Electric Power Company,Tianjin 300151,China;College of Civil Engineering and Architecture,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]国网天津市电力公司经济技术研究院,天津300151 [2]哈尔滨工业大学土木工程学院,哈尔滨150090 [3]国网天津市电力公司,天津300151 [4]浙江大学建筑工程学院,杭州310058

出　　处：《硅酸盐学报》2021年第2期331-339,共9页Journal of The Chinese Ceramic Society

基　　金：国网天津市电力公司科技项目(KJ20-1-45)。

摘　　要：为揭示水泥基材料低温冻融孔结构损伤的演变规律,以饱水白水泥砂浆为研究对象,利用低场磁共振技术测试了砂浆试件在连续冻融循环作用下的孔结构。设计了20℃常规养护和80℃高温养护制度以改变砂浆的初始孔隙结构,随后对这两种相同配比、不同孔结构的砂浆进行快速和慢速冻融循环试验。结果表明:80℃高温养护会显著降低砂浆抗冻性,增大凝胶孔并提高粗毛细孔体积分数,但不会显著改变介观毛细孔的分布强度;与高温养护作用相反,冻融循环作用不会改变凝胶孔和粗毛细孔的分布强度,但能显著提高微裂纹的分布强度;80℃高温养护砂浆在冻融作用下的微裂纹体积增长速率显著高于20℃常规养护砂浆;冻融速率不会显著影响砂浆的孔径分布变化规律;砂浆内部微裂纹体积增大和质量损失增加呈双线性关系。砂浆内部冻融破坏和外部剥落均主要源自于微裂纹的产生和发展,与凝胶孔和粗毛细孔无明显相关性。To reveal the evolution of pore structure damage of cement-based materials under cyclic freeze-thaw(F–T)loads,a typical white cement mortar was used as a research object,and the pore structure of the mortar saturated with water under certain F-T cycles was characterized by the low-field magnetic resonance(LF-NMR)spectroscopy.Mortar specimens were cured at 20℃and 80℃to yield the different initial pore structures,and suffered from fast and low F–T loads.The results show that the F–T resistance of mortar decreases,the distributions of the gel pores and the macro-capillary pores increase,but those of the meso-capillary pores maintain when curing in hot water at 80℃.By contrast,F–T load has a slight impact on the gel pores and macro-capillary pores,and enhances the distribution of micro-cracks.The rate of rising the micro-cracks under F–T loads for the mortar specimens cured at 80℃is greater than that for the mortar specimens cured at 20℃.F–T rate has little influence on the pore structure evolution of the mortar.The micro-crack ratio is bi-linearly related to the mass loss ratio.The internal deterioration and surface spalling of the mortar under F-T loads are mainly induced by the generation and development of the micro-cracks in the mortar matrix,showing no direct association with the gel pores and macro-capillary pores.

关 键 词：水泥 砂浆 孔结构 抗冻性 低场磁共振 

分 类 号：TU528.1[建筑科学—建筑技术科学]