超低水胶比复合胶凝材料孔结构随养护制度和龄期的变化机理

发布时间：2018-05-28 05:42

本文选题：超低水胶比 + 孔结构　；参考：《硅酸盐学报》2017年11期

【摘要】：基于超低水胶比复合胶凝材料早期收缩发展的特殊规律,通过化学结合水和内部湿度测量,初步判断硬化浆体孔结构的特殊变化;通过压汞法(MIP)和氮吸附法(BET)测量特征龄期硬化浆体的孔结构,揭示了养护条件和水化龄期对超低水胶比复合胶凝材料早期孔结构的影响规律;并通过扫描电子显微镜和透射电子显微镜深入研究了孔结构变化的微观机理。结果表明:超低水胶比复合胶凝材料密封养护的早期收缩值大于干燥条件,随着龄期的增加,硬化浆体内部20~30 nm的凝胶单元间孔逐渐增大并增多,而早期生成3~12 nm的凝胶粒子间孔逐渐减少,部分小于3 nm的凝胶微晶间孔也受到了压缩。这一作用的驱动力是水化中后期的自干燥作用,水化硅酸钙凝胶在二次水化和后期水化作用下,形成了球状的压缩凝胶单元,尺寸由50 nm缩至20~40 nm,引起凝胶粒子间孔的压缩和凝胶单元间孔的增加。孔结构的变化不会显著影响材料的力学性能、抗渗性能和耐久性能,但改变了硬化浆体的早期收缩发展规律。
[Abstract]:Based on the special law of early shrinkage development of ultralow water / binder composite cementing materials, the special changes of pore structure of hardened paste were preliminarily judged by chemical combination of water and internal humidity measurement. The pore structure of hardened paste of characteristic age was measured by mercury injection method (MIP) and nitrogen adsorption method (BET), and the effect of curing condition and hydration age on the early pore structure of ultra-low water / binder composite cementing material was revealed. The micromechanism of pore structure was studied by scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the early shrinkage of the composite cementing material with ultra-low water binder ratio is larger than that of the drying condition. With the increase of age, the intercellular pore of 2030 nm gel in the body of hardened paste increases and increases gradually. However, the intergranular pores of 3nm-12 nm gel particles were gradually reduced in the early stage, and some of the intergranular pores of gel particles less than 3 nm were also compressed. The driving force of this action is self-drying in the middle and late stage of hydration. The hydrated calcium silicate gel forms a spherical compression gel unit under the secondary hydration and later hydration. The size was reduced from 50 nm to 20 ~ 40 nm, which resulted in the compression of the pore between the gel particles and the increase of the pore between the gel units. The change of pore structure will not significantly affect the mechanical properties, impermeability and durability of the material, but it will change the early shrinkage and development of hardened slurry.
【作者单位】：北京交通大学土木与建筑工程学院;
【基金】：中央高校基本科研业务费专项资金(2016JBM045) 国家自然科学基金(51408037,51578049) 交通运输部应用基础研究项目(2014319494010) 中交集团科技研发(2013-ZJKJ-11)资助项目
【分类号】：TU528

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