碱矿渣胶结材低温水化行为与早期微观结构

Hydration Behaviour and Early Microstructure of Alkali-Activated Slag Binder at Low Temperature

研究了NaOH、水玻璃激发矿渣砂浆在5℃环境下抗压强度的发展,采用电阻率、选择性溶解法、压汞法(MIP)和扫描电子显微镜(SEM)分析了碱矿渣胶结材(AAS)低温水化过程及其早期微观结构.结果表明:碱矿渣胶结材在5℃环境下能持续水化,但其水化速度和抗压强度发展速度低于标准养护试件;在相同条件下,水玻璃激发AAS砂浆抗压强度较高,但其电阻率和水化程度低于NaOH激发AAS砂浆.另外,碱矿渣胶结材在5℃环境下养护1d时,硬化浆体孔隙率和大孔增加,其内部存在大量未反应微小矿渣颗粒,水化产物层薄弱、结构不密实,导致其早期强度发展缓慢.

The compressive strength development of NaOH and water glass activated slag mortar cured at 5℃was studied.Bulk resistivity,selective dissolution,mercury intrusion porosimetry(MIP),scanning electron microscopy(SEM)were used to analyze and characterize the low temperature hydration processes and early microstructures of alkali-activated slag binder(AAS).The results show that alkali-activated slag binder can hydrate at 5℃,while the rates of compressive strength development and hydration are lower than that of samples cured at standard curing condition.Under the same conditions,the compressive strength of mortar activated by water glass is higher,but the bulk resistivity and hydration degree are lower than those activated by NaOH.When samples are cured at 5℃for 1d,the porosity and macropores increase,while weak hydration product layers and large amounts of unreacted tiny slag particles are found in hardened paste,which leads to a slow growth rate of early strength.