华中科技大学学报（自然科学版）2025，Vol.53Issue(2)：142-149,8.DOI:10.13245/j.hust.250047
基于CPMG及SE-SPI序列NMR技术高温后混凝土孔隙及吸水行为研究
Study on pore evolution and water absorption of concrete after high temperatures based on CPMG and SE-SPI sequence NMR technology
摘要
Abstract
To investigate the effect of high temperature on the internal pore evolution and capillary water absorption behavior of concrete,the capillary water absorption test was carried out on the concrete specimens treated with high temperatures of 20,400,600,and 800℃.The changes in the internal pore structure of the concrete after high temperatures were analyzed by the Nuclear Magnetic Resonance(NMR)technique using the CPMG sequences,and the changes in the internal pore structure of the concrete after high temperatures were also investigated at the three-dimensional level by the NMR technique using the SE-SPI sequences to explore the water absorption behavior of concrete under the effect of different water absorption behavior of concrete under the impact of high temperature.The results show that with the increase in temperature,the percentage of macropores and capillaries inside the concrete increases,and the micropores and mesopores decrease;however,at 400℃,the products of gel decomposition and secondary hydration fill some of the pores,resulting in the decrease of macropores,capillaries,and mesopores,and the increase of micropores.In addition,after the action of high temperature,the water absorption process of concrete is as follows:at the initial stage,the water penetrates rapidly into the mesopores and capillaries,then gradually expands to the micropores and macropores.The NMR test reveals that there are obvious differences in the T2 spectrum signals at different temperatures:at 200℃and 400℃,the T2 spectrum is mainly a single peak,and the water-absorption process mainly occurs in the capillary pores;at 600℃,the T2 spectral curve shows a bimodal distribution,and the water-absorption process mainly occurs in the capillary pores;and at 800℃,the T2 spectral curve is a bimodal one at the beginning,and then it evolves into a trimodal one at the later stage,and then the water-absorption process mainly takes place in the macropores.关键词
孔隙演化/吸水行为/核磁共振/高温作用/混凝土Key words
pore evolution/water absorption behavior/nuclear magnetic resonance/high-temperature/concrete分类
建筑与水利引用本文复制引用
田威,郭健,程续,云伟..基于CPMG及SE-SPI序列NMR技术高温后混凝土孔隙及吸水行为研究[J].华中科技大学学报（自然科学版）,2025,53(2):142-149,8.基金项目
国家自然科学基金资助项目(52479115) （52479115）
陕西省重点研发计划资助项目(2024SF-YBXM-615) （2024SF-YBXM-615）
陕西高校青年创新团队项目([2022]943). （[2022]943）
