过火煤矸石对中等密度泡沫混凝土性能的影响

发布时间：2018-03-29 19:40

本文选题：泡沫混凝土　切入点：煤矸石　出处：《哈尔滨工业大学》2017年硕士论文

【摘要】：泡沫混凝土是一种新型轻质建筑材料,具有优良的保温、隔热、隔音、耐火以及抗震性能,非常适合用来作为隔墙、填充材料来使用。随着装配式建筑行业的快速发展,采用中等密度等级泡沫混凝土实现大型建筑隔墙的工厂化预制生产具有较大发展潜力。而煤矸石作为一种采煤废弃物,其大量堆积引起的环境污染越来越严重,需要寻找新的回收利用煤矸石的途径。因此,本课题通过掺加过火煤矸石粉制备中等密度等级泡沫混凝土,具有重要的社会与环境效益。首先以普通水泥砂浆为基础制备了不同密度等级的泡沫混凝土,并研究了浆体流变性对泡沫稳定性的影响以及体积密度与强度之间的关系等。结果表明,泡沫混凝土的流动性随减水剂掺量的增加而增大;相同灰砂比和水灰比时,泡沫混凝土的体积密度随泡沫的体积掺量呈线性降低趋势,灰砂比为1:2、1:1.5和1:1时,当泡沫掺量范围分别为48%~57%、46%~54%和48%~55%时,可制得体积密度为1000kg/m3~1200kg/m3的泡沫混凝土;随着泡沫混凝土体积密度的增加,灰砂比为1:2和1:1.5时,各龄期的强度呈指数型增长;灰砂比为1:1时,呈线性增长。在普通水泥砂浆制备泡沫混凝土的基础上,通过调整粉磨时间制备了不同细度的煤矸石粉,研究了其不同掺量对泡沫混凝土性能的影响。结果表明,粉磨45min的煤矸石粉细度和水泥相当;煤矸石粉的掺入不利于泡沫混凝土的流动,但可以增加砂粒和气泡的稳定性;掺煤矸石泡沫混凝土的体积密度随煤矸石掺量增加而降低,强度随煤矸石粉掺量增加显著降低,随煤矸石粉活性的增加而提高。最后研究了蒸汽养护对掺煤矸石泡沫混凝土强度的影响以及用XRD分析了其水化产物。结果表明,预养护8h后的掺煤矸石泡沫混凝土合适的蒸养温度为40oC;蒸汽养护可显著提高掺煤矸石泡沫混凝土的1d强度,蒸养18h的1d强度可达3MPa,对7d和28d强度影响不大。相对于自然养护,蒸养下1d样品中含有较多Ca(OH)2和较少SiO2,说明蒸养可促进水泥水化和火山灰反应的进程;28d龄期的掺煤矸石泡沫混凝土中Ca(OH)2含量明显降低,CaCO3含量明显增加,此时试件中进行了较多的火山灰反应和碳化反应;而活性较低的煤矸石粉参与火山灰反应较缓慢,28d样品中Ca(OH)2含量较多。
[Abstract]:Foamed concrete is a new type of lightweight building material with excellent insulation, insulation, sound insulation, fire resistance and seismic resistance. It is very suitable for use as partition wall, filling material, and with the rapid development of assembly construction industry, It has great development potential to use medium density grade foam concrete to realize the industrial prefabrication of partition wall of large building. As a kind of coal mining waste, the environmental pollution caused by mass accumulation of coal gangue is becoming more and more serious. It is necessary to find a new way to recycle coal gangue. Therefore, in this paper, the medium density grade foamed concrete is prepared by adding excessive coal gangue powder. It has important social and environmental benefits. Firstly, foam concrete with different density grades is prepared on the basis of ordinary cement mortar. The effect of rheology on foam stability and the relationship between bulk density and strength are studied. The results show that the fluidity of foamed concrete increases with the increase of water reducer content, and when the ratio of cement to sand is the same as the ratio of water to cement, The volume density of foamed concrete decreases linearly with the volume content of foam. When the ratio of lime to sand is 1: 2: 1: 1.5 and 1:1, the volume density of foamed concrete can be obtained when the volume ratio of foam is 48 ~ 5746% and 48 ~ 5555%, respectively, and the volume density of foam concrete is 1000kg/m3~1200kg/m3. With the increase of bulk density of foamed concrete, the strength of each age increases exponentially when the ratio of lime to sand is 1:2 and 1: 1.5, and linearly when the ratio of lime to sand is 1:1. Coal gangue powder with different fineness was prepared by adjusting grinding time, and the effect of different content of coal gangue powder on the properties of foamed concrete was studied. The results show that the fineness of coal gangue powder of grinding 45min is equal to that of cement. The mixing of coal gangue powder is unfavorable to the flow of foamed concrete, but it can increase the stability of sand and bubble, the volume density of coal gangue foam concrete decreases with the increase of coal gangue content, and the strength decreases with the increase of coal gangue powder content. The effect of steam curing on the strength of coal gangue foamed concrete and the hydration products were analyzed by XRD. The suitable steaming temperature of foamed concrete mixed with coal gangue is 40oC after 8 hours of pre-curing, and the 1d strength of foamed concrete mixed with coal gangue can be significantly increased by steam curing, and the strength of foamed concrete by steam curing for 18h can reach 3MPa, which has little effect on the strength of 7d and 28d. More Ca(OH)2 and less Sio _ 2 were found in the samples after 1 d of steam culture, which indicated that the process of steaming can promote the hydration of cement and the reaction of pozzolanic ash. The content of Ca(OH)2 in coal gangue foamed concrete with 28 d age obviously decreased and the content of Caco _ 3 increased obviously. At this time, more pozzolanic reaction and carbonation reaction were carried out in the samples, and the Ca(OH)2 content in the samples with lower activity of coal gangue involved in the slow reaction of pozzolanic ash was more than 28 days.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.2

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