为进一步提升低温环境下矿渣基地聚物砂浆的力学性能,以矿渣、硅灰和偏高岭土为主要原料制备了4种地聚物砂浆,探究不同原料组合对地聚物砂浆力学性能的提升效果,并结合扫描电镜和傅里叶红外光谱试验分析了不同组合地聚物砂浆的微观结构和硅灰、偏高岭土的改性机理。结果表明:在低温环境10℃的养护下,掺加硅灰可极大促进矿渣基地聚物砂浆早期水化反应,生成大量的C-S-H凝胶与水化铝酸钙产物,宏观上表现出更高的早期力学性能和强度增长速率;掺加偏高岭土,对矿渣基地聚物砂浆的早期力学性能有不利影响,但后期强度增长速率较快且强度值较高,养护时间为28d时,矿渣-偏高岭土基(S-MK)、矿渣-硅灰-偏高岭土基地聚物砂浆(S-SF-MK)试件的抗压强度均达60MPa以上;掺入硅灰和偏高岭土后,试件微观结构得到了改善,内部裂缝减少,均降低了地聚物砂浆的干缩率,偏高岭土降低干缩的效果较硅灰更好。研究结果为低温环境下矿渣基地聚物砂浆的制备和寒区抢修工程的应用提供了理论参考。
In order to further improve the mechanical properties of slag-based geopolymer mortars under low temperature environment,four geopolymer mortars were prepared with slag,silica fume and metakaolin as the main raw materials.The improvement effects of different raw material combinations on the mechanical properties of geopolymer mortars were explored.The microstructures of geopolymer mortars with different combinations and the modification mechanisms of silica fume and metakaolin were analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy.The results showed that the addition of silica fume could greatly promote the early hydration reaction of slag-based geopolymer mortar under low temperature environment of 10℃,and generate a large number of C-S-H gel and hydrated calcium aluminate products,showing higher early mechanical properties and strength growth rate macroscopically.The addition of metakaolin had a negative impact on the early mechanical properties of slag-based geopolymer mortar,but the late strength growth rate was fast and the strength value was high.When the curing time was 28d,the compressive strength of slag-metakaolin base (S-MK) and slag-silica fume-metakaolin base geopolymer mortar (S-SF-MK) specimens were above 60MPa.After adding silica fume and metakaolin,the microstructure of the specimen was improved and the internal cracks decreased,which reduced the dry shrinkage rate of geopolymer mortar.The effect of metakaolin on reducing dry shrinkage was better than that of silica fume.The research results provided a theoretical reference for the preparation of slag-based geopolymer mortar under low temperature environment and the application of emergency repair project in cold regions.
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基金资助
国家自然科学基金(51908548,52278287);国家人民防空办公室立项课题(RF20SC01J—S0);陕西省高校科协青年人才托举计划项目(20200415)
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