Accelerated carbonation testing of alkali-activated binders significantly underestimates service life: The role of pore solution chemistry
Accelerated carbonation testing of alkali-activated binders significantly underestimates service life: The role of pore solution chemistry
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DOI：
10.1016/j.cemconres.2012.07.002
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发表时间：
2012-10-01
影响因子：
11.4
通讯作者：
van Deventer, Jannie S. J.
中科院分区：
文献类型：
--
作者：
Bernal, Susan A.;Provis, John L.;van Deventer, Jannie S. J.
碱激发粘结剂的抗碳化性能通常是通过为波特兰水泥设计的加速测试方案来测试的，而不会质疑测试是否复制了在使用中观察到的机制。因此，需要对加速方法进行验证，以实现对材料性能的真实预测。与自然碳化中的水合碳酸钠相比，在加速碳化过程中，孔隙溶液平衡的变化会导致碳酸氢钠的形成。这改变了碳化机制，有利于更快的反应进程，提供比波特兰水泥更高的表观加速程度(与自然条件相比)。加速碳化下的孔溶液pH值显著低于自然二氧化碳浓度，导致错误地预测使用寿命(嵌入式钢预期腐蚀的时间)，因为自然二氧化碳浓度似乎不会将pH值降低到10以下。因此，加速碳化试验对碱活性粘结剂过于咄咄逼人，必须谨慎解释试验结果。(C)2012爱思唯尔有限公司。保留所有权利。
The carbonation resistance of alkali-activated binders is often tested via accelerated test protocols designed for Portland cements, without questioning whether the tests replicate the mechanisms observed in service. Thus, validation of accelerated methods is required to enable realistic prediction of material performance. Changes in pore solution equilibria cause the formation of sodium bicarbonates during accelerated carbonation, compared with hydrous sodium carbonates in natural carbonation. This shifts the carbonation mechanism to favour more rapid reaction progress, to give a higher apparent degree of acceleration (compared to natural conditions) than in Portland cements. The pore solution pH under accelerated carbonation is significantly lower than at natural CO2 concentrations, leading to a falsely short predicted service life (time to expected corrosion of embedded steel), as natural CO2 concentrations appear not to reduce the pH below 10. Thus, accelerated carbonation testing is unduly aggressive towards alkali-activated binders, and test results must be cautiously interpreted. (C) 2012 Elsevier Ltd. All rights reserved.