铁道科学与工程学报2025，Vol.22Issue(3)：1121-1131,11.DOI:10.19713/j.cnki.43-1423/u.T20240804
低气压环境下水泥砂浆干缩和微结构演变研究
Investigation on drying shrinkage and microstructure evolution of mortar under low pressure environment
摘要
Abstract
With the continuous promotion of the national western development strategy,concrete structures will face the severe test of special service environmental conditions in the plateau region.Complex service environment conditions on the microstructure of cement concrete,there is a significant impact on the performance.Combined with the current situation of service in the western region of China and the major needs of engineering construction,the corresponding low-pressure environment simulation conditions were built indoors for the low-pressure service environment in the Tibetan Plateau region.The effects of three air pressure ambient conditions(1 atm,0.8 atm and 0.6 atm)on the macroscopic properties of cement mortar,such as mechanical strength,dynamic modulus and drying shrinkage and deformation,at 60%relative humidity and 20℃temperature were investigated.Further microscopic testing methods such as thermogravimetric,piezomercury,X-ray diffraction and Fourier infrared spectroscopy were used to analyze the degree of hydration,the composition of physical phases,and the changes in the pore structure of the net mortar specimens under the above atmospheric pressure environment conditions,and to explore the influencing mechanism of the low-pressure environment in affecting the volumetric stability of the cementitious materials.The results are as follows.Compared to normal pressure environments,low-pressure environments exacerbate the drying shrinkage deformation and mass loss of cement mortar,leading to adverse effects on its mechanical properties and dynamic modulus.Additionally,low air pressure environments reduce the hydration degree of cement,increase the total porosity,harmful pores,and the proportion of capillary pores(<50 nm)in cement paste,but do not alter the composition of hydration products in cement-based materials.The critical pore size of mortar decreases with decreasing environmental pressure,and capillary negative pressure is the main driving mechanism for drying shrinkage deformation of cement mortar under the investigated conditions.The results can provide important insights for ensuring the performance of concrete structures in high-altitude areas of the western plateau.关键词
低气压环境/砂浆/干缩/孔结构/机理Key words
low air pressure environment/mortar/drying shrinkage/pore structure/mechanism分类
建筑与水利引用本文复制引用
王海旭,梅文勇,汤聪,唐卓,廖志泓,龙广成..低气压环境下水泥砂浆干缩和微结构演变研究[J].铁道科学与工程学报,2025,22(3):1121-1131,11.基金项目
国家重点基础研究计划(2023YBF2604304) （2023YBF2604304）
广铁集团科技研究开发计划(2023K107-Z) （2023K107-Z）
辽宁省教育厅基本科研项目-青年项目(LJ212410153094) （LJ212410153094）
