原生硫酸复盐对水泥性能的影响

发布时间：2018-04-04 12:23

本文选题：原生硫酸钠钾　切入点：原生硫酸钾钙　出处：《重庆大学》2015年硕士论文

【摘要】：随着生产技术的发展和节能减排的需要,硅酸盐水泥熟料中原生硫酸盐含量明显提高,一些固硫技术的发展使混合材中SO3含量进一步提高。为了预防和抑制水泥中过多硫酸盐带来的不利影响,一般都对水泥总SO3含量,也包括混合材的SO3含量,进行限制,这使得高硫废渣难以得到实际应用,人们甚至担心熟料中过高的硫含量引起的不利影响。在水泥生产中通常还需要掺入二水石膏,如果水泥熟料和混合材中的原生硫酸盐能一定程度上代替二水石膏使用,则不必过于担心熟料中的原生硫酸盐,甚至可以利用SO3含量超过规定的废渣。因此我们必须了解原生硫酸盐与二水石膏对水泥性能影响的差异。①采用高温合成法模拟制备了原生硫酸钠钾、原生硫酸钾钙。原生3K2SO4·Na2SO4模拟煅烧制度为1000oC,保温时间2h。原生2CaSO4·K2SO4模拟煅烧制度为920oC,保温时间2h。采用水溶法测试了模拟制备的原生硫酸复盐与天然二水石膏溶解特性的差异,溶解速率:硫酸钠钾硫酸钾钙二水石膏。②在水泥中掺入原生硫酸钠钾、原生硫酸钾钙以研究原生硫酸复盐对水泥凝结时间、强度、体积稳定性的影响。原生硫酸复盐能显著延长水泥凝结时间、提高早期强度、改善水泥体积稳定性,但不同原生硫酸复盐对水泥性能的作用与二水石膏相比有所差异,总体上原生硫酸钠钾的作用次于二水石膏,原生硫酸钾钙的作用和二水石膏相近。③在不同铝酸三钙含量的水泥中掺入原生硫酸钠钾和原生硫酸钾钙,并测试各水泥体系的凝结时间、强度和体积稳定性,以研究铝酸三钙含量对原生硫酸复盐作用的影响。凝结时间方面,原生硫酸钠钾的缓凝作用随铝酸三钙含量提高急剧下降,当水泥中铝酸三钙含量达到11.8%时,即使提高原生硫酸钠钾掺量也不能使水泥的凝结时间达到国家标准要求;原生硫酸钾钙的缓凝作用受铝酸三钙影响较小,即使铝酸三钙含量提高,原生硫酸钾钙仍能较好地调节水泥凝结时间。强度和体积稳定性方面,原生硫酸钠钾能提高水泥早期强度但却使水泥后期强度倒缩,且硫酸钠钾作用的水泥其收缩和膨胀都较二水石膏和硫酸钾钙作用的水泥大;原生硫酸钾钙能使水泥强度提高,同时具有良好的体积稳定性。总体上硫酸钠钾作用次于二水石膏,受铝酸三钙含量影响显著;硫酸钾钙的作用与二水石膏差别不大,受铝酸三钙含量变化的影响较小。④采用XRD和SEM等测试手段研究硫酸钠钾、硫酸钾钙对水泥水化产物及微观形貌的影响。纯熟料和掺有不同硫酸盐的水泥其水化产物并没有显著不同,主要水化产物仍然是水化硅酸钙以及Ca(OH)2等。但掺有原生硫酸钠钾和原生硫酸钾钙的水泥体系其微观形貌有比较明显的区别,硫酸钠钾水泥体系扫描电镜图片中存在较多氢氧化物,而原生硫酸钾钙水泥体系比较致密。
[Abstract]:With the development of production technology and the need of energy saving and emission reduction, the content of original sulfate in Portland cement clinker is obviously increased, and the content of SO3 in the mixture is further increased with the development of some sulfur fixation technologies.In order to prevent and suppress the adverse effects of excessive sulfate in cement, the total SO3 content of cement and the SO3 content of mixed materials are generally restricted, which makes it difficult for high-sulfur waste slag to be applied in practice.There is even concern about the adverse effects of excessive sulfur content in clinker.It is often necessary to add gypsum dihydrate in cement production. If the original sulphate in cement clinker and mixture can replace gypsum dihydrate to some extent, it is not necessary to worry too much about the original sulfate in clinker.Even the waste residue containing more than specified SO3 content can be used.Therefore, we must understand the difference between primary sulfate and gypsum dihydrate on the properties of cement. 1. The primary sodium sulfate potassium potassium sulfate and primary potassium potassium sulfate calcium were prepared by high temperature synthesis method.The simulated calcination system of original 3K2SO4 Na2SO4 is 1000oC, and the holding time is 2 h.The simulated calcination system of primary 2CaSO4 K2SO4 is 920oC, and the holding time is 2 h.The dissolution characteristics of the simulated primary sulfate compound salt and natural gypsum were measured by water solution method. The dissolution rate was as follows: sodium potassium sulfate potassium potassium sulfate calcium dihydrate gypsum .2 was mixed with primary sodium potassium sulfate in cement.The effect of primary sulfate compound on setting time, strength and volume stability of cement was studied.The primary sulphuric acid compound salt can significantly prolong the setting time of cement, increase the early strength and improve the volume stability of cement, but the effect of different primary sulphuric acid compound salt on cement properties is different from that of gypsum dihydrate.On the whole, the effect of primary sodium potassium sulfate is inferior to that of gypsum dihydrate, and the effect of primary potassium potassium sulfate calcium sulfate is similar to that of gypsum dihydrate. 3. The primary sodium sulfate potassium potassium sulfate and primary potassium potassium sulfate calcium are mixed in cement with different contents of tricalcium aluminate.The setting time, strength and volume stability of each cement system were tested to study the effect of tricalcium aluminate content on the primary sulfate compound.When the setting time is concerned, the retarding effect of primary sodium and potassium sulfate decreases sharply with the increase of tricalcium aluminate content, when the content of tricalcium aluminate in cement reaches 11.8%,The setting time of cement can not reach the national standard even if the content of original sodium and potassium sulfate is increased, and the retarding effect of primary potassium sulfate calcium sulfate is less affected by tricalcium aluminate, even though the content of tricalcium aluminate is increased,Primary calcium potassium sulfate can still adjust the setting time of cement.In terms of strength and volume stability, primary sodium and potassium sulfate can increase the early strength of cement, but make the later strength of cement shrink, and the shrinkage and expansion of cement treated by sodium and potassium sulfate are larger than that of gypsum dihydrate and calcium potassium sulfate.Primary calcium potassium sulfate can increase the strength of cement and has good volume stability.On the whole, the action of sodium and potassium sulfate was inferior to that of gypsum dihydrate, and was significantly affected by the content of tricalcium aluminate, but the effect of potassium calcium sulfate was not different from that of gypsum dihydrate.The effects of sodium potassium sulfate and potassium sulfate calcium sulfate on the hydration products and micromorphology of cement were studied by means of XRD and SEM.The hydration products of pure clinker and cement mixed with different sulfate are not significantly different. The main hydration products are still calcium silicate hydrate and Ca(OH)2 etc.However, the microcosmic morphology of cement system mixed with primary sodium potassium sulfate and primary potassium sulfate calcium sulfate is obviously different. There are many hydroxides in the SEM picture of sodium potassium sulfate cement system, while the original calcium potassium sulfate cement system is relatively compact.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.1

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