Temperature and activator effect on early-age reaction kinetics of alkali-activated slag binders
Temperature and activator effect on early-age reaction kinetics of alkali-activated slag binders
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DOI：
10.1016/j.conbuildmat.2016.03.098
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发表时间：
2016-06-15
影响因子：
7.4
通讯作者：
Peethamparan, Sulapha
中科院分区：
文献类型：
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作者：
Gebregziabiher, Berhan Seium;Thomas, Robert J.;Peethamparan, Sulapha
采用原位等温量热法研究了碱激发矿渣胶凝材料的早期反应动力学。特别注意活化剂类型（氢氧化钠和硅酸钠）和浓度以及固化温度（23 ℃和50 ℃）的影响。机械强度的发展，微观结构，和产品相组成也进行了讨论，提供上下文的动力学结果中观察到的现象。结果表明，对于两种活化剂，高温固化大大加速了水化，导致更快的产品形成和强度发展。高摩尔浓度的氢氧化钠活化剂显示出在环境温度下加速早期水化，但倾向于对高级水化呈现障碍，从而限制后期强度。高温固化被证明可以通过提高溶解度和扩散性来消除这种对高级水化的障碍。硅酸钠活化矿渣的水化相对较慢，导致延迟形成具有较高机械强度的非常致密的产品。增加氧化钠倾向于加速水合作用，导致早期和后期强度的改善，而增加二氧化硅倾向于延迟反应，导致更慢、更完全的水合作用以及机械强度的改善。(C)2016爱思唯尔有限公司版权所有
The early-age reaction kinetics of alkali-activated ground granulated blast-furnace slag (GGBFS) binders as determined by in-situ isothermal calorimetry are discussed in this paper. Particular attention is paid to the effects of activator type (sodium hydroxide and sodium silicate) and concentration, as well as curing temperature (23 degrees C and 50 degrees C). The mechanical strength development, microstructure, and product phase composition are also discussed to provide context for the phenomena observed in the kinetics results. It is shown for both activators that elevated temperature curing greatly accelerates hydration, resulting in more rapid product formation and strength development. High-molarity sodium hydroxide activators are shown to accelerate early hydration at ambient temperature, but tend to present a barrier to advanced hydration thereby limiting the later-age strength. Elevated temperature curing is shown to remove this barrier to advanced hydration by improving solubility and diffusivity. Hydration of sodium silicate-activated slag is comparatively slow, resulting in the delayed formation of very dense products with higher mechanical strength. Increasing sodium oxide tends to accelerate hydration, resulting in improved early- and later-age strength, while increasing the silica tends to retard the reaction, resulting in slower, more complete hydration as well as improved mechanical strength. (C) 2016 Elsevier Ltd. All rights reserved.