高温蒸汽养护混凝土试件强度损失的原因分析

Analysis on the strength loss of steam cured concrete

对比观察了标准条件养护和高温蒸汽养护的混凝土内部硬化浆体的化学组成、水化产物和浆体形貌,以分析高温蒸汽养护的混凝土强度损失的原因。两种条件下养护的混凝土内部硬化水泥浆体的化学组成与水化产物种类相同;高温蒸汽养护后硬化水泥浆体中有大量粗大的氢氧化钙和水化硫铝酸钙晶体,使硬化水泥浆体结构疏松,晶体物质与CSH凝胶结合不紧密,导致混凝土强度发展受到抑制,最终强度很低。

This study investigated the chemical compositions, hydration products and microstructure of hardened cement paste under standard curing and 50-60 ℃ steam-curing to analyze the reason of strength loss of steam cured concrete. The chemical compositions and hydration products of hardened cement paste are similar in two curing conditions. There are lots of coarse Ca (OH)2 and sulfoaluminate hydrate crystal in the cement paste cured with steam, which results in a loose paste structure and the weak connection between crystalline hydrate and C-S-H gel. This phenomenon results in an inhibited strength development and a low ultimate strength for steam-cured concrete.