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通过压汞法测量孔隙分布、孔隙率和体积、特征孔隙尺寸、孔隙比表面积和曲折度,研究了养护条件对密封养护净浆和砂浆试件的孔隙结构的影响。结果表明:密封养护对水泥基材料的比表面作用较小,但是能显著提高其孔隙率;密封养护加剧自干燥作用,导致水泥基材料在10～100nm和100～1000nm区间出现明显的孔隙分布峰,且峰强和最可几尺寸均随着水灰比的增加而增加;密封养护导致水泥基材料的临界孔隙尺寸减小但是对平均孔径均影响较小;净浆和砂浆的退汞残余和曲折度均随着水灰比的增加而降低,且曲折度与孔隙率的关系大致符合指数规律。密封养护条件下自干燥导致微结构变化的模型表明:水泥基材料在低含水量条件下水化不充分,孔隙压力大,容易出现连通的大毛细孔和微裂纹;水灰比越大,该现象越明显。
The pore distribution, porosity and volume, characteristic pore size, specific surface area of pores and tortuosity were measured by mercury intrusion porosimetry. The influence of curing conditions on the pore structure of the seal and the mortar was studied. The results show that the seal curing has less effect on the specific surface of cement-based materials, but can significantly improve the porosity of the cement-based materials; the self-drying effect of seal curing aggravates the obvious pore distribution peaks of cement-based materials in the range of 10-100 nm and 100-1000 nm , And the peak intensity and the most probable size all increased with the increase of water-cement ratio. The sealing maintenance resulted in the decrease of the critical pore size of cement-based materials but less affected the average pore size. The tortuosity decreases with the increase of water-cement ratio, and the relationship between tortuosity and porosity roughly accords with exponential law. The model of self-desiccation-induced microstructure change under the condition of sealed curing shows that cement-based materials are not sufficiently hydrated under low water content and have large pore pressure, which leads to the appearance of large pores and microcracks. The larger the water-cement ratio, The more obvious.