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Micro- and nano-structural evolutions in white Portland cement/pulverized fuel ash cement pastes due to deionized-water leaching
Cement and Concrete Research ( IF 11.4 ) Pub Date : 2018-01-01 , DOI: 10.1016/j.cemconres.2017.10.014
Shanshan Jia , Ian G. Richardson

Abstract Thin slices of white Portland cement-low calcium pulverized fuel ash (pfa) blended cement pastes containing 30 or 50% pfa were leached progressively in de-ionized water. The paste with 50% pfa was aged 13 years prior to leaching and those with 30% pfa were aged 1 and 13 years. Pastes were leached for up to 75 days and were characterized using thermal analysis, X-ray diffraction, analytical scanning and transmission electron microscopy, and solid-state nuclear magnetic resonance spectroscopy. Leaching affected the pastes in the following sequence: (i) crystals of Ca(OH)2 large enough to be resolved by backscattered electron imaging were removed completely prior to any effect on C-A-S-H; (ii) the Ca/Si ratio of C-A-S-H reduced from ≈ 1.4 to ≈ 1.0 whilst the aluminosilicate structure was unaffected; (iii) further reduction in the Ca/Si ratio of C-A-S-H was accompanied by lengthening of the aluminosilicate chains; (iv) the Ca/Si ratio of C-A-S-H reduced ultimately to ≈ 0.6.

中文翻译:

由于去离子水浸出,白色波特兰水泥/粉煤灰水泥浆的微结构和纳米结构演变

摘要 在去离子水中逐渐浸出含有 30% 或 50% pfa 的白色波特兰水泥 - 低钙粉煤灰 (pfa) 混合水泥浆的薄片。含 50% pfa 的糊状物在浸出前老化 13 年,而含 30% pfa 的糊状物分别陈化 1 年和 13 年。糊状物浸出长达 75 天,并使用热分析、X 射线衍射、分析扫描和透射电子显微镜以及固态核磁共振光谱进行表征。浸出按以下顺序影响糊剂:(i) 在对 CASH 产生任何影响之前,完全去除足以通过背散射电子成像分辨的 Ca(OH)2 晶体;(ii) CASH 的 Ca/Si 比从 ≈ 1.4 降低到 ≈ 1.0,而铝硅酸盐结构不受影响;(iii) CASH 的 Ca/Si 比的进一步降低伴随着铝硅酸盐链的延长;(iv) CASH 的 Ca/Si 比率最终降低到 ≈ 0.6。
更新日期:2018-01-01
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