Na2SiO3/Na2CO3复合制备清洁型碱矿渣胶凝材料

为解决弱碱单独激发碱矿渣胶凝材料(AASM)时存在的力学性能弱、矿渣反应程度低等问题,缓解AASM的操作危害性,本文采用Na₂SiO₃/Na₂CO₃复合激发矿渣,研究了复合激发剂组成对AASM凝结时间、抗压强度、水化产物及自收缩的影响,并评估了AASM的环境效益。结果表明:随着Na₂CO₃碱当量的增加,AASM缓凝效果较为明显,抗压强度也有所降低,但抗压强度的降低幅度随龄期增大而减小。通过加入Na₂CO₃,AASM水化产物种类增多,C-(A)-S-H的峰值强度随Na₂CO₃碱当量占比的增加呈现出先增加后降低的趋势,因而解释了AASM浆体自收缩的变化。另外,由CO₂排放指数可以看出,Na₂SiO₃/Na₂CO₃复合激发矿渣较Na₂SiO₃单独激发更为清洁,环境效益显著。

Preparation of Clean Alkali-Activated Slag Cementitious Material by Combined Activator of Na2SiO3/Na2CO3

This study is aimed to solve the problems of weak mechanical properties and low degree of slag reaction when weak single alkali-activated slag cementitious material(AASM),and to alleviate the operational hazards of AASM.Therefore,a combined activator of Na₂SiO₃/Na₂CO₃ was used to investigate its influence on the setting time,compressive strength,hydration products and autogenous shrinkage of AASM.Moreover,the environmental benefit of AASM was assessed.The experimental results show that the retarding effect is significant and the compressive strength is reduced with the increase of Na₂CO₃ alkali dosage,whereas the reduction rate of compressive strength is slightly decreased as the hydration time increased.More types of hydration products are produced by adding Na₂CO₃.The amount of C-(A)-S-H increased first follow by a decrease with the increase of Na₂CO₃ alkali dosage,thus explaining the changes in the autogenous shrinkage.Furthermore,based on the CO₂emission index,the combined Na₂SiO₃/Na₂CO₃ activated slag is produced in a cleaner manner with greater environmental benefit,compare to the Na₂SiO₃ activated slag.