矿渣水化生成LDHs机理及其对水泥基材料抗硫酸盐侵蚀性能的影响研究

发布时间：2018-03-07 15:52

本文选题：水淬玻璃体　切入点：矿渣　出处：《武汉理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：矿渣作为一种常见的矿物掺合料被广泛应用于现代混凝土领域。现阶段研究认为,矿渣在混凝土中的作用机理主要体现为微集料效应、微晶核效应和活性效应等三个方面。微集料效应促使混凝土形成最紧密堆积结构,微晶核效应减小界面有害晶体的尺寸,活性效应增加凝胶组分含量,三者都起到增强混凝土密实度的作用。本文着眼于矿渣的化学组成,研究矿渣水化产物,尤其是LDHs型水化产物在抗硫酸盐侵蚀中的作用。本文的研究成果将为混凝土防腐技术开拓新的思路。矿渣主体为非晶态玻璃体,矿渣活性与玻璃体含量及自身细度密切相关。本文以矿渣玻璃体三维网络结构理论为依据,采用混合均匀的氧化物经高温熔融-水淬冷却的方法,成功合成了较为纯净的水淬玻璃体。以水淬玻璃体模拟高炉矿渣,探究矿渣水化产物的形貌、种类、数量与其化学组成的关系,并论证了LDHs型水化产物的数量与其镁含量成正比。将水淬玻璃体掺入硅酸盐水泥熟料,与粉煤灰一并组成水泥基材料,采用硫酸盐干湿循环的加速侵蚀实验方法对水泥基材料进行处理,测试其抗硫酸盐侵蚀性能,采用XRD、SEM、XEDS等测试手段对其微观机理进行分析。实验研究表明:1、以CaO、Si O2、Al2O3及MgO的混合物经高温熔融、水淬冷却,可以得到含极少量硅酸盐矿物晶体的玻璃体,称之为水淬玻璃体。通过原料配比计算,可设计出所需化学组成的水淬玻璃体,并以此模拟高炉矿渣。非桥氧数反映玻璃体三维网络结构聚合度,可以作为预测水淬玻璃体活性的重要指标。矿渣活性不仅受玻璃体聚合度影响,还跟其细度有关系。2、水淬玻璃体的主要水化产物类型为C-S-H(I)与Mg-Al水滑石,其中Mg-Al水滑石为LDHs型水化产物。随着矿渣镁含量的提高,LDHs型水化产物的数量增多,水化28天龄期以后不再随龄期的延长而发生明显变化。3、掺水淬玻璃体的水泥基材料抗硫酸盐侵蚀性能与对照组相比有明显改善。随干湿循环次数的增加,试件表现出先收缩后膨胀的特点,试件质量表现出先增加后减少的规律,吸水率表现为持续上升,强度则表现为持续降低。4、与碱激发矿渣相比,粉煤灰-矿渣-熟料水泥基材料的水化产物中Mg-Al水滑石含量较少,并与C-S-H凝胶共存,难以直接观测。该水泥基材料受硫酸盐侵蚀后Ca(OH)2含量减少,侵蚀产物主要为针棒状钙矾石。
[Abstract]:Slag, as a common mineral admixture, is widely used in the field of modern concrete. The micronucleus effect and the active effect promote the formation of the most compact stacking structure of concrete. The micronucleus effect decreases the size of the harmful crystal at the interface, and the active effect increases the content of the gel component. All three play an important role in enhancing the compactness of concrete. This paper focuses on the chemical composition of slag and studies the hydration products of slag. Especially the role of LDHs hydration products in sulfate corrosion resistance. The research results in this paper will open up a new way of thinking for concrete anticorrosion technology. The main body of slag is amorphous vitreous body. The activity of slag is closely related to the content of vitreous body and the fineness of vitreous body. Based on the theory of 3D network structure of slag vitreous body, this paper adopts the method of mixing homogeneous oxide through high temperature melting and water quenching cooling. A relatively pure water-quenched vitreous body was successfully synthesized. The water quenched vitreous body was used to simulate blast furnace slag, and the relationship between the morphology, species, quantity and chemical composition of the hydration product of slag was investigated. It is demonstrated that the quantity of LDHs hydration product is proportional to its magnesium content. Water quenched glass is mixed with Portland cement clinker to form cement based material with fly ash. The accelerated erosion test method of sulphate dry-wet cycle was used to treat cement based materials, and the resistance to sulfate erosion was tested. The microcosmic mechanism was analyzed by means of XRD-SEMS-XEDS. The experimental results show that glass containing a small amount of silicate mineral crystals can be obtained by using the mixture of Cao Si O 2 O 2 Al 2O 3 and MgO by melting at high temperature and cooling by water quenching. It is called water-quenched vitreous body. By calculating the proportion of raw material, the water-quenched vitreous body with chemical composition can be designed, and the blast furnace slag can be simulated. The unbridged oxygen number reflects the degree of 3D network aggregation of vitreous body. The activity of slag is affected not only by the degree of vitreous polymerization, but also by its fineness. The main hydration products of water-quenched vitreous body are C-S-HNI) and Mg-Al hydrotalcite. Among them, Mg-Al hydrotalcite is the hydration product of LDHs type, and the quantity of LDHs hydration product increases with the increase of slag magnesium content. After 28 days of hydration, there was no obvious change with the prolongation of the age. The resistance to sulfate erosion of the cement based materials with water quenched vitreous was obviously improved compared with the control group, and with the increase of dry-wet cycle times, the resistance to sulfate erosion of the cement based materials with water quenched vitreous was improved obviously compared with the control group. The specimen showed the characteristics of first shrinkage and then expansion. The quality of the specimen was increased first and then decreased. The water absorption rate increased continuously, and the strength decreased by .4. compared with the alkali-activated slag, the quality of the specimen increased firstly and then decreased. The content of Mg-Al hydrotalcite in the hydration products of fly ash, slag and clinker cement-based materials is less and coexists with C-S-H gel, so it is difficult to observe directly. The Ca(OH)2 content of the cement based material is reduced after sulfate erosion, and the main product is needle-rod ettringite.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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