干燥大温差环境下水泥胶凝材料开裂敏感性研究  

Study on the crack sensitivity of cementitious materials in dry and large temperature difference environments

作　　者：熊根亿 王怀义 杨桂权 李双喜[1] 程宁宁 XIONG Genyi;WANG Huaiyi;YANG Guiquan;LI Shuangxi;CHENG Ningning(College of Water Conservancy and Civil Engineering,Xinjiang Agricultural University,Urumqi 830052,China;Xinjiang Research Institute of Water Resources and Hydropower,Urumqi 830049,China;Xinjiang Engineering and Technology Research Center of Water Resources and Hydropower Materials,Urumqi 830049,China)

机构地区：[1]新疆农业大学水利与土木工程学院,新疆乌鲁木齐830052 [2]新疆水利水电科学研究院,新疆乌鲁木齐830049 [3]新疆水利水电材料工程技术研究中心,新疆乌鲁木齐830049

出　　处：《水利水运工程学报》2025年第2期103-111,共9页Hydro-Science and Engineering

基　　金：中央引导地方科技发展专项(ZYYD2023B04)。

摘　　要：针对中国西北地区干燥大温差环境造成水泥基材料的裂缝,从而严重影响混凝土结构寿命的难题,利用环形约束试验中应变突变时间表征水泥胶凝材料在不同环境条件下的开裂敏感性。通过显微观察、计算机断层扫描(CT)及压汞法的测试,揭示了在干燥大温差环境下水泥胶凝材料的约束收缩变形、开裂情况及其开裂机理。研究发现:当水胶比从0.25提高到0.35时,开裂时间可延长370.59%;湿度降低40%时,水胶比为0.30试件的开裂时间缩短20.30%;当日温差为35℃时,水胶比为0.25试件的开裂时间延长40.63%;掺加30%粉煤灰可使开裂时间延长4.41倍;影响材料开裂敏感性大小的因素依次为水胶比、粉煤灰和温湿度条件,其中水胶比为0.25的试样对温度最敏感,水胶比为0.30的试样对湿度变化较敏感。研究结果表明干燥和大温差的环境条件加剧了水泥胶凝材料的开裂风险。水胶比的增加降低了水泥胶凝材料开裂的风险,粉煤灰能有效抑制水泥胶凝材料的开裂,降低材料开裂敏感性,并揭示了水胶比、粉煤灰掺加与环境温湿度变化导致胶凝材料孔结构的演变对开裂敏感性影响的机理。Addressing the issue of cracking in cement-based materials caused by dry and large temperature difference environments in Northwest China,which significantly impacts the lifespan of concrete structures,this study characterizes the crack sensitivity of cementitious materials under varying environmental conditions using strain abrupt change time in ring-restrained tests.Microscopic observation,computed tomography(CT),and mercury intrusion porosimetry(MIP)were employed to elucidate the mechanisms of restrained shrinkage deformation,cracking behavior,and cracking mechanisms of cementitious materials in dry and large temperature difference environments.The findings revealed that increasing the water-to-cement ratio(fW/C)from 0.25 to 0.35 extended the cracking time by 370.59%;a 40%reduction in humidity shortened the cracking time of specimens with a fW/C of 0.30 by 20.30%;and a daily temperature difference of 35℃increased the cracking time of specimens with a fW/C of 0.25 by 40.63%.Adding 30%fly ash extended the cracking time by 4.41 times.Factors affecting cracking sensitivity were ranked as follows:fW/C,fly ash content,and temperature-humidity conditions.Samples with a fW/C of 0.25 were most sensitive to temperature changes,while those with a fW/C of 0.30 were more sensitive to humidity variations.The results demonstrate that dry and large temperature difference environments exacerbate cracking risks in cementitious materials.Increasing the fW/C reduced cracking risks,and incorporating fly ash effectively suppressed cracking,thereby mitigating material sensitivity to cracking.The study also elucidated the mechanisms by which fW/C,fly ash addition,and environmental temperaturehumidity variations influence pore structure evolution and cracking sensitivity in cementitious materials.

关 键 词：干燥大温差 粉煤灰 开裂敏感性 

分 类 号：TU526[建筑科学—建筑技术科学]