生物质灰对水泥基复合胶凝材料水化硬化性能的影响研究

发布时间：2018-03-25 09:21

本文选题：生物质灰　切入点：水泥基复合胶凝材料　出处：《山东农业大学》2017年硕士论文

【摘要】：生物质能是一种清洁可再生能源,我国生物质能资源丰富。应用生物质发电可对二氧化碳以及多种大气污染物减排有显著效果。当前我国以生物质为燃料的电厂发展迅速,生物质灰的去向也亟待解决。国内外很多学者针对生物质灰在水泥混凝土中的应用开展研究,发现生物质灰中含有一些类似于粉煤灰的物相和化学组成,具有广泛的价值潜力。但现有的研究仍无法在工业化生产中应用,还有大量的理论研究工作需要完成。本文对比分析了生物质灰与普通粉煤灰在粒度分布、颗粒形态、化学组成、活性指数、需水量比等方面的不同,通过研究复合水泥胶砂强度的变化规律以及硬化浆体的水化性能、矿物组成、微观结构、孔结构等,对比分析生物质灰和普通粉煤灰对水泥基复合胶凝材料水化硬化机理的影响,结果表明:在基本性能测试方面,生物质灰颗粒形状不规则、平均粒径及粒径分布范围较大,具有特有的细长纤维状颗粒,且其活性组分Al2O3不足普通粉煤灰的三分之一;生物质灰的火山灰活性小于普通粉煤灰。在水化初期,生物质灰对复合胶凝材料强度贡献主要以物理填充作用为主,随着养护龄期的延长其火山灰效应逐渐显现,强度得以提高。相同掺量下,生物质灰-水泥复合胶砂各龄期的抗压强度、抗折强度均小于普通粉煤灰-水泥复合胶砂,但对抗折强度的削弱影响较小。生物质灰掺量越大,复合胶砂的强度相比纯水泥组下降程度越大。生物质灰与粉煤灰的掺入均降低了复合胶凝材料的总水化程度,但体系中水泥水化程度却由于生物质灰与粉煤灰的稀释作用而得到促进;生物质灰与粉煤灰的掺量越大,水泥的水化程度越高。生物质灰与粉煤灰的掺入导致水化产物中Ca(OH)2的含量减少,但对水泥水化产物的种类影响较小,由于普通粉煤灰的活性大于生物质灰,因而其火山灰反应消耗更多氢氧化钙,所发挥的二次水化作用强于生物质灰试验组。生物质灰和粉煤灰的掺入减少了体系中的有害孔及多害孔的总数量,使孔径得到了细化,体系中少害孔及无害孔增多,硬化浆体结构朝着对耐久性有利的方向发展。与普通粉煤灰相比,掺加生物质灰的硬化水泥浆体微观形貌更为疏松多孔,特别是其特有的细长纤维状颗粒的存在。
[Abstract]:Biomass energy is a kind of clean and renewable energy, and our country is rich in biomass energy resources. The application of biomass power generation can reduce carbon dioxide and many kinds of atmospheric pollutants significantly. At present, the power plants with biomass as fuel are developing rapidly in our country. Many scholars at home and abroad have carried out research on the application of biomass ash in cement concrete, and found that biomass ash contains some phase and chemical composition similar to fly ash. But the existing research can not be used in industrial production, and a lot of theoretical research work needs to be completed. The particle size distribution and particle morphology of biomass ash and ordinary fly ash are compared and analyzed in this paper. Chemical composition, activity index, water demand ratio, etc., by studying the change law of composite cement sand strength and the hydration property, mineral composition, microstructure, pore structure of hardened mortar, etc., The effects of biomass ash and ordinary fly ash on the hydration and hardening mechanism of cement-based composite cementitious materials are compared and analyzed. The results show that the shape of biomass ash particles is irregular and the average particle size and particle size distribution range is large. It has special slender fibrous particles, and its active component Al2O3 is less than 1/3 of ordinary fly ash, and the pozzolanic activity of biomass ash is lower than that of ordinary fly ash. The contribution of biomass ash to the strength of composite cementitious materials is mainly physical filling. With the prolongation of curing age, the pozzolanic effect of biomass ash gradually appears and the strength is improved. The compressive strength and flexural strength of biomass ash-cement compound mortar at each age are smaller than those of ordinary fly ash cement compound cement sand, but the weakening of flexural strength has little effect. The strength of composite cement sand decreased more than that of pure cement group. The addition of biomass ash and fly ash decreased the total hydration degree of composite cementing material. However, the degree of cement hydration in the system is promoted by the dilution of biomass ash and fly ash. The higher the hydration degree of cement is, the lower the content of Ca(OH)2 in hydration products is due to the addition of biomass ash and fly ash, but the less the effect on the kinds of hydration products is, because the activity of ordinary fly ash is higher than that of biomass ash. As a result, the pozzolanic reaction consumes more calcium hydroxide and exerts a stronger secondary hydration effect than the biomass ash test group. The addition of biomass ash and fly ash reduces the total number of harmful pores and multiple harmful pores in the system and refines the pore size. With the increase of less harmful and harmless pores in the system, the structure of hardened slurry develops in a direction favorable to durability. Compared with ordinary fly ash, the microstructure of hardened cement paste with biomass ash is more porous and porous. In particular, the existence of its unique slender fibrous particles.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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