Studies on delayed ettringite formation in early-age, heat-cured mortars: I. Expansion measurements, changes in dynamic modulus of elasticity, and weight gains
Studies on delayed ettringite formation in early-age, heat-cured mortars: I. Expansion measurements, changes in dynamic modulus of elasticity, and weight gains
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早期热固化砂浆中钙矾石延迟形成的研究：I. 膨胀测量、动态弹性模量的变化和重量增加
DOI：
10.1016/s0008-8846(02)00862-1
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
S. Diamond
中科院分区：
文献类型：
--
作者：
Zhaozhou Zhang;J. Olek;S. Diamond
砂浆由实验室水泥制备，该实验室水泥由一组六种代表性的研磨熟料和Terra Alba石膏混合而成。石膏的加入使得生产的水泥含有小于最佳SO3含量1%的SO3、最佳SO3含量和大于最佳SO3含量1%的SO3。将含有这些水泥中的每一种的砂浆棒和砂浆立方体暴露于连续室温（23 °C）固化，或暴露于涉及55和85 °C的最高温度的早期固化循环，然后在100%RH下在水中长期暴露，但不浸入水中。测量膨胀，动态弹性模量，和增重记录在高达900天的间隔。在由六种“过硫酸盐”水泥中的四种水泥制成的85 °C固化砂浆棒中观察到严重开裂和显著的延迟钙矾石形成（DEF）诱导的膨胀。在85 °C下固化的两种具有最佳SO3含量的水泥的砂浆棒中观察到小得多的膨胀。对于任何55 °C或连续室温固化的砂浆，均未观察到膨胀或其他可见的损坏迹象。动态弹性模量逐渐增加，长期暴露的未受影响的砂浆棒，但它急剧下降后，在受影响的砂浆棒的膨胀发病。在扩张过程中，重量也显著增加。当作为砂浆棒暴露时显示出严重开裂和劣化的砂浆在作为立方体暴露时几乎没有可见的损坏。
Mortars were prepared from laboratory cements blended from a set of six representative ground clinkers and Terra Alba gypsum. The addition of gypsum was such that cements containing 1% SO3less than the optimum SO3content, the optimum SO3content, and 1% greater than the optimum SO3content were produced. Mortar bars and mortar cubes containing each of these cements were exposed to continuous room temperature (23 °C) curing, or to early-age curing cycles involving maximum temperatures of 55 and 85 °C, followed by long-term exposure at 100% RH over water, but not immersed in water. Measurements of expansion, dynamic elastic modulus, and weight gain were recorded at intervals of up to 900 days. Severe cracking and prominent delayed ettringite formation (DEF)-induced expansions were observed in 85 °C cured mortar bars derived from four of the six “oversulfated” cements. Much smaller expansions were observed in mortar bars from two cements with optimum SO3content cements also cured at 85 °C. No expansion or other visible indication of distress was observed for any of the 55 °C or continuously room-temperature-cured mortars. The dynamic elastic modulus increased progressively on prolonged exposure for the unaffected mortar bars, but it decreased precipitously after the onset of expansion in affected mortar bars. Significant weight increases also accompanied the processes of expansion. Mortars that showed severe cracking and deterioration when exposed as mortar bars suffered almost no visible damage when exposed as cubes.