MgO/硅酸钠复合对碱矿渣水化和力学特性的影响

Effect of MgO/Sodium Silicate Composite Activator on Hydration and Mechanical Properties of Alkali-Activated Slag Materials

为促进MgO基单组分碱激发矿渣胶凝材料(AASM)的发展和应用,采用MgO和硅酸钠作为激发剂,通过单独及复合激发的方式,研究了MgO和硅酸钠组合形式对单组分AASM水化微结构和力学特性的影响,并采用纳米压痕分析了其微观力学性能.结果表明:加入MgO后,会形成Mg(OH)2,可提供碱性环境,促使矿渣溶解;硅酸钠溶解后,会进一步提升溶液pH值,加速矿渣Al—O、Si—O键断裂以及Ca^(2+)等溶出,形成双重强化效应,促进矿渣水化;MgO/硅酸钠复合激发时,体系产生了相对单独激发时更丰富的水化产物;孔结构分析发现,复合激发时AASM具有最小的孔隙率,且有害孔隙最少;两者复合激发时会产生更多的高弹性模量水化产物,较强的微观力学性能则促使宏观力学强度的提高.

To promote the development and application of MgO-based single component alkali-activated slag materials(AASM),MgO was used as activators or along with sodium silicate for elucidation of their effects on hydration microstructure and mechanical properties of single component AASM.Moreover,micro-mechanical properties were also analyzed by nanoindentation.Results show that the formation of Mg(OH)2after MgO contacted with water provides an alkaline environment,which induces the dissolution of slag.While the dissolution of sodium silicate further elevates the solution pH value and accelerates the fracture of Al—O and Si—O chemical bond as well as the release of Ca^(2+).This forms a double strengthening effect to promote the hydration of slag.In addition,the composite activator of MgO and sodium silicate produces more abundant hydration products.Pore structure analysis reveals that AASM has the lowest porosity and the least harmful pores by using the combined MgO and sodium silicate to activate slag.More hydration products with high elastic modulus are produced in combination with MgO and sodium silicate,thus contributing to the increase in micro-mechanical properties.