水泥—矿渣复合胶凝材料的水化机理与长期性能

发布时间：2018-06-28 13:43

本文选题：矿渣 + 复合胶凝材料　；参考：《清华大学》2013年博士论文

【摘要】：矿渣作为一种辅助性胶凝材料，大量用于配制混凝土。这可以综合利用工业废渣，减少水泥用量，，具有较好的环境效应和经济效应。为了保证用其配制的混凝土的耐久性，水泥矿渣复合胶凝材料浆体在服役环境中的长期性能值得关注。本文对水泥矿渣复合胶凝材料的水化机理和长期性能进行了研究，主要研究内容和相关结论如下： (1)水泥矿渣复合胶凝材料在常温养护下，矿渣早期反应速率慢，后期反应程度提高较多；矿渣掺量不大于70%时，掺量对其反应程度影响不大，水泥矿渣复合胶凝料硬化浆体孔溶液pH值达到12.6以上时，可较好地激发矿渣的活性；水泥矿渣复合胶凝材料的总反应程度低于纯水泥；高温养护能较好地激发早期矿渣的活性，使矿渣早期的反应程度提高，但后期没有进一步提升矿渣的反应程度；化学结合水量法不能准确地表征水泥矿渣复合胶凝材料的反应程度。 (2)矿渣早期的水化反应会消耗Ca(OH)2。在其活性被激发后，水化后期不再消耗较多Ca(OH)2，水泥矿渣复合胶凝浆体中的Ca(OH)2含量较低；常温养护下早期水泥矿渣复合胶凝材料硬化浆体的微观结构较为疏松，后期明显改善，孔隙结构优化；早期高温养护使复合胶凝材料浆体微观结构得到显著改善；水泥矿渣复合胶凝材料中C S H凝胶的Ca/Si比较低，矿渣反应生成的低Ca/Si比的C S H凝胶呈箔片状，代替水泥水化生成的纤维状C S H凝胶，能更有效地填充孔隙。 (3)矿渣水化反应主要生成微观力学性能高的HD C S H凝胶，凝胶的微观力学性能与其堆积密实度相关，与其化学组成无关。矿渣反应生成含Al的C A S H凝胶，且Al在桥四面体位置替代Si；随着龄期的延长，凝胶的平均直链长度增加，随着矿渣掺量的增加，C A S H凝胶的平均硅铝链长度增大，Al/Si比增加。 (4)水泥矿渣复合胶凝材料硬化浆体遭受长期软水溶蚀后，Ca(OH)2含量仍充足，C S H凝胶的Ca/Si比稍有降低，但没有分解的迹象。水泥矿渣复合胶凝材料硬化浆体的孔隙率更低，表现出更好的抗溶蚀性。用水泥矿渣复合胶凝材料制备的混凝土中，Ca(OH)2含量降低，碳化深度较大，但满足长期稳定性的要求。 (5)矿渣掺量不超过70%时，水泥矿渣复合胶凝材料硬化浆体具有更加密实的微观结构，浆体中Ca(OH)2含量的适量减少和孔溶液碱度的降低，没有影响复合胶凝材料浆体微观结构的长期稳定性。
[Abstract]:As an auxiliary cementitious material, slag is widely used in the preparation of concrete. It can make comprehensive use of industrial waste slag, reduce cement consumption, and have better environmental and economic effects. In order to ensure the durability of concrete prepared with it, the long-term performance of cement and slag composite cement paste in service environment is worthy of attention. In this paper, the hydration mechanism and long-term performance of cement-slag composite cementing materials are studied. The main research contents and relevant conclusions are as follows: (1) Cement-slag composite cementing materials are cured at room temperature. The reaction rate of slag is slow in early stage and the reaction degree in later stage is much higher. When the slag content is less than 70, the effect of slag content on the reaction degree is not significant. When the pH value of cement / slag composite cement hardened slurry pore solution reaches more than 12.6, It can excite the activity of slag better, the total reaction degree of cement-slag composite cementitious material is lower than that of pure cement, the activity of early slag can be better stimulated by high temperature curing, and the early reaction degree of slag can be improved. However, the reaction degree of slag was not further improved in the later stage, and the reaction degree of cement slag composite cementitious material could not be accurately characterized by chemical binding water method. (2) Ca (OH) _ 2 was consumed in the early hydration reaction of slag. After its activity was stimulated, Ca (OH) _ 2 was no longer consumed at the later stage of hydration, the content of Ca (OH) _ 2 in the cement slag composite cement paste was lower, and the microstructure of the cement and slag composite cement paste was looser in the early stage of curing at room temperature. In the later stage, the pore structure was optimized, the microstructure of cement paste was obviously improved by early high temperature curing, and the Ca / Si ratio of C / S / H gel was relatively low in the cement-slag composite cementing material. The C / S / H gel with low Ca / Si ratio produced by slag reaction is a foil sheet instead of a fibrous C / S / H gel formed by hydration of cement. (3) the hydration reaction of slag mainly produces HD C / S / H gel with high micromechanical properties. The micromechanical properties of the gel are related to its packing compactness, but not to its chemical composition. The slag reacts to form the Al / C / A / S / H gel and Al replaces Si in the bridge tetrahedron, and the average straight chain length of the gel increases with the increase of age. With the increase of slag content, the average length of silica-aluminum chain increases and the ratio of Al / Si increases. (4) the content of Ca (OH) _ 2 is still sufficient after the cement paste is corroded by soft water for a long time. The Ca / Si ratio of the adhesive is slightly lower, But there is no sign of decomposition. The porosity of cement and slag composite cementing material is lower and the corrosion resistance is better. The content of Ca (OH) _ 2 in concrete prepared from cement and slag composite cementing material is lower and the carbonization depth is larger, but it can meet the requirements of long-term stability. (5) when the slag content is not more than 70%, The hardened paste of cement and slag composite cementing material has more dense microstructure. The decrease of Ca (OH) _ 2 content in the slurry and the decrease of alkalinity of pore solution do not affect the long-term stability of the paste microstructure of the composite cementing material.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528

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