蒸压条件下粉煤灰水化机理及应用研究

发布时间：2018-05-27 12:42

  本文选题：水化硅酸钙 + 托贝莫来石　； 参考：《中北大学》2017年硕士论文

【摘要】：粉煤灰是燃煤电厂排放出的固体废弃物,不仅占用大量土地,而且污染环境。粉煤灰制备免烧砖可以提高粉煤灰的利用率,避免了大量使用粘土、煤等不可再生资源,同时,利用粉煤灰制备成免烧砖可以使煤基固废得到循环利用。粉煤灰免烧砖在北方寒冷地区经过冻融循环后容易出现开裂、强度降低等现象。仅仅通过改变原料配比并不能有效解决粉煤灰免烧砖抗冻性问题,研究发现养护制度对粉煤灰免烧砖抗冻性有很大影响,而反应温度和时间是影响养养护制度的两个最重要因素。为了优化蒸压粉煤灰免烧砖的性能并制备出抗冻性较好的粉煤灰免烧砖,本文通过研究粉煤灰与生石灰在不同蒸压温度(120℃、140℃、160℃、180℃、200℃)和时间(4h、6h、8h、10h)下水化产物矿物组成和形貌来阐述粉煤灰在蒸压下的水化机理。为了在较短反应时间内制备出满足抗冻性要求的粉煤灰免烧砖,在粉煤灰水化机理的基础上,设计了不同的养护制度,通过抗冻性试验得出了最优的养护制度,结论如下:(1)蒸压温度≤140℃时,即使反应时间延长到10h也不会生成大量结晶度较好的托贝莫来石,当蒸压温度≥160℃时,160℃下,反应10h时含铝托贝莫来石含量达到最大,180℃下,反应6h时含铝托贝莫来石的含量达到最大,200℃下,反应6h时含铝托贝莫来石的含量达到最大。(2)通过X射线衍射K值法分析得出:反应温度≤140℃时,反应10h内,随着反应时间延长,水化石榴石含量逐渐增加;反应温度≥160℃时,随着反应时间延长水化石榴石含量基本不发变化。(3)反应温度≤140℃时,产物的形貌以卷箔状居多,此外也有少量团絮状、颗粒状、板状水化产物,延长反应时间水化产物搭接越来越致密。反应温度≥160℃时,160℃反应6h出现“鱼鳞”片状水化产物;180℃反应10h出现大量叶片状水化产物;温度为200℃时有纤维状水化产物生成。(4)粉煤灰免烧砖在200℃下养护3h,然后在180℃下养护3h,经过该养护制度后的粉煤灰免烧砖抗冻性比较优异,满足制品的抗冻性要求。
[Abstract]:Fly ash is a solid waste discharged from coal-fired power plants, which not only occupies a lot of land, but also pollutes the environment. The utilization ratio of fly ash can be improved by using fly ash to prepare no-fired brick, and a large number of non-renewable resources such as clay and coal can be avoided. At the same time, coal-based solid waste can be recycled by using fly ash to prepare no-fired brick. Fly ash brick is prone to crack and decrease in strength after freeze-thaw circulation in the cold area of northern China. Only by changing the ratio of raw material can not effectively solve the problem of freezing resistance of fly ash free fired brick. The research found that the curing system has a great influence on the freezing resistance of fly ash free fired brick. The reaction temperature and time are the two most important factors affecting the maintenance system. In order to optimize the properties of autoclaved fly ash unfired brick and prepare fly ash brick with good frost resistance, In this paper, the hydration mechanism of fly ash and quicklime under autoclaved pressure was studied by studying the mineral composition and morphology of hydration products of fly ash and quicklime at different autoclaved temperatures (120 鈩，

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