内掺Ca(OH)2对碱矿渣混凝土水化进程的影响

Effect of Calcium Hydroxide on Hydration Process of Alkali Activated Slag Concrete

关键词:  碱矿渣混凝土  Ca(OH)2  坍落度损失  水化进程

Key words:  alkali activated slag concrete(AASC)  calcium hydroxide  slump loss  hydration process

摘要:

以钠水玻璃为激发剂，用Ca(OH)2等量取代矿渣，研究了不同水胶比下Ca(OH)2对碱矿渣混凝土早期性能的影响.使用水化动力学分析、X射线衍射(XRD)及扫描电子显微镜(SEM)分析了碱矿渣混凝土的水化过程.结果表明：掺入Ca(OH)2后，碱矿渣混凝土的凝结速率增大并造成快速坍落度损失；当Ca(OH)2掺量（质量分数）分别为5%和10%时，碱矿渣混凝土中水泥加速期的水化反应速率常数(K)由476×10-5分别增长至560×10-3和156×10-2，水泥水化诱导期显著缩短，Ca(OH)2主要作用于水化加速期，同时水化加速期反应级数(N)由289分别减小至126和098，意味着加速期反应由反应物通过致密层生成物扩散控制逐渐转变成反应物沉积控制；Ca(OH)2加快了24h内碱矿渣水泥的水化，并生成了C2ASH8及C4AH13等水化产物.

Abstract:

The effect of isometric substitute of calcium hydroxide on early stage performance of alkali activated slag concrete(AASC) was investigated. The hydration process of alkali activated slag cement was analysed using hydration kinetics analysis, X ray diffraction and scanning electron microcopy. The results show that the addition of Ca(OH)2 can accelerate the hydration of AASC, leading to a faster slump loss. The acceleration reaction rate constant(K) of alkali activated slag cement increased from 476×10-5 to 560×10-3 and 156×10-2 by addition of 5% and 10%(by mass) Ca(OH)2, which shows that the addition of Ca(OH)2 mainly affects the acceleration period and the hydration induction period is shortened. Simultaneously, the reaction degree(N) decreases from 289 to 126 and 098, which means that the hydration process is controlled by sedimentation of reactant rather than the diffusion controlled process. The hydration process in 24h of alkali activated slag cement is accelerated by adding Ca(OH), with the formation of C2ASH8 and C4AH13.