MgO活性对无机聚合物硬化浆体体积变形及微观结构的影响

Effects of MgO Activity on Volumetric Deformation and Microstructure of Hardened Geopolymer Pastes

无机聚合物胶凝材料是一种新型胶凝材料,具有早期强度快硬、结构致密的特点,且抗腐蚀性能优异,可应用于滨海和海洋工程基础设施建设。但该类材料存在收缩大、易开裂的缺陷,严重影响了其工程应用。结合无机聚合物快硬早期强度的特点,研究了高活性(60 s)、中活性(150 s)及低活性(220 s)氧化镁(Mg O)对无机聚合物硬化浆体的体积变形及微观结构的影响。结果表明:Mg O活性对无机聚合物性能影响显著,60 s活性Mg O促进无机聚合物的水化放热,提高了无机聚合物硬化浆体的早期强度,且硬化浆体的早期收缩值最低,硬化浆体的改善效果也最好;150 s和220 s活性Mg O延缓了无机聚合物水化放热,但改善了无机聚合物长龄期的体积收缩;Mg O加入到无机聚合物中与水反应生成了Mg(OH)2,从而改善无机聚合物的体积收缩。

Geopolymer,a novel cementitious material of superb corrosion resistance and quick setting and big strength in early stage,is applied to offshore and coastal projects.It is also,however,subject to cracking and large volume shrinkage which limit its engineering application.In this paper,the effects of MgO of high activity(60 s),medium activity(150 s)and low activity(220 s)on the volumetric shrinkage and microstructure of hardened geopolymer pastes were examined respectively.Results revealed remarkable influence of MgO activity on geopolymer performance:MgO of high activity could improve the early-stage strength of hardened geopolymer pastes by enhancing hydration heat release,and the early shrinkage value of the hardened pastes were the lowest;on the contrary,MgO of medium activity and low activity postponed the hydration heat release,and alleviated the volumetric shrinkage by acting with water in the geopolymer.