掺偏高岭土蒸养混凝土的微观结构与性能研究

发布时间：2018-02-09 17:38

本文关键词： 蒸养混凝土偏高岭土性能水化程度微观结构　出处：《宁波大学》2017年硕士论文　论文类型：学位论文

【摘要】：论文针对蒸养混凝土预制构件存在的关键技术问题和当前我国建筑工业化对蒸养混凝土预制构件的重大需求,系统地研究了偏高岭土作为矿物掺合料对蒸养混凝土性能及微观结构的影响。对比标准养护条件,研究了水胶比、偏高岭土掺量、复掺矿物掺合料以及龄期等因素对蒸养混凝土工作性、力学性能、耐久性的影响,并采用电镜观察、孔结构、热分析等微观测试技术探讨了偏高岭土对水泥水化程度、微观形貌及结构的影响。主要结论如下:(1)掺偏高岭土对拌合物工作性能影响较大。控制胶砂流动度在(135±10)mm之间,减水剂用量随偏高岭土掺量增大而增加,当偏高岭土掺量为25%时,减水剂(水剂)用量为6%;随偏高岭土比表面积增大,减水剂用量增大。(2)偏高岭土提高了蒸养混凝土力学性能。偏高岭土显著改善了混凝土脱模强度,单掺偏高岭土15%时,脱模强度提高19.8%。掺偏高岭土蒸养混凝土的后期强度持续增长。偏高岭土对蒸养混凝土力学性能的改善效果与硅灰相当,明显好于矿渣及粉煤灰。细度较大的偏高岭土对砂浆强度的增强效果更好。(3)掺偏高岭土可有效改善蒸养混凝土毛细吸水性和抗氯离子渗透性。随养护龄期增长、偏高岭土掺量增加或水胶比减小,蒸养混凝土毛细水吸附系数和氯离子扩散系数均呈下降趋势并逐渐趋稳,养护的前28 d降低速率较快。当水胶比低于0.35、掺量达到15%,28 d及90 d龄期掺偏高岭土蒸养混凝土的毛细吸水性和抗氯离子渗透性能与标养混凝土相当,甚至优于标养混凝土。(4)偏高岭土能提高蒸养混凝土抵抗硫酸盐结晶侵蚀的能力。半浸泡条件下,空白组蒸养混凝土的抗蚀系数、质量变化先升高后降低,掺入偏高岭土后,抗蚀系数有所增加,质量变化幅度较空白组低。(5)电镜、热分析和孔结构数据表明,偏高岭土能显著加快水化进程,促进水化凝胶等产物的生成。掺偏高岭土能减少蒸养混凝土中Ca(OH)2含量,降低孔隙率,增加C-S-H凝胶等产物的含量。脱模龄期时,复掺20%偏高岭土蒸养混凝土中的Ca(OH)2已基本被火山灰反应消耗。单掺15%偏高岭土蒸养混凝土90 d龄期Ca(OH)2含量仅空白组的一半。
[Abstract]:According to the great needs of the key technical problems of autoclaved concrete prefabricated components exist and the current construction of industrialization of autoclaved concrete prefabricated components, systematically studied the metakaolin as mineral admixture, curing and microstructure of concrete performance of steam. Compared with standard curing conditions of water binder ratio, metakaolin content, factors of mineral admixtures and curing time of concrete maintenance work, the mechanical properties of steam, durability, and observed by electron microscopy, pore structure, thermal analysis and microscopic test technology of metakaolin on cement hydration degree, influence of morphology and structure. The main conclusions are as follows: (1) large influence of metakaolin on workability. Control mortar fluidity in (135 + 10) mm, dosage of polycarboxylate superplasticizer with metakaolin content increased when the metakaolin content is 25%, water reducing Agent (agent) was 6%; with the partial kaolin were surface area increases, reducing agent dosage increased. (2) metakaolin improves the mechanical properties of steam curing concrete. Metakaolin significantly improved concrete demoulding strength, single metakaolin 15%, demoulding strength increased 19.8%. metakaolin vapor strength a concrete continuous growth. To improve the effect of metakaolin and silica fume to raise mechanical properties of concrete is better than steam, slag and fly ash. Better effect of fineness of metakaolin on strength of mortar. (3) with metakaolin to effectively improve autoclaved concrete capillary water absorption and resistance to chloride ion permeability. Increase with curing time, metakaolin content increasing or decreasing water cement ratio, autoclaved concrete capillary water adsorption coefficient and diffusion coefficient of chloride ion decreased and gradually stabilized, the maintenance of 28 d before the reduction rate is fast. When the water cement ratio Less than 0.35, the content reached 15%, 28 d and 90 d age metakaolin autoclaved concrete capillary water absorption and resistance to chloride ion permeability and standard curing concrete is even better than that of standard concrete. (4) the metakaolin can improve the resistance of steam curing concrete sulfate crystallization attack ability. Soaking condition, the blank group of steam curing concrete corrosion resistance coefficient, mass change increased first and then decreased, the incorporation of metakaolin, corrosion resistance coefficient increased, quality variation lower than control group. (5) electron microscopy, thermal analysis and pore structure data show that metakaolin can significantly accelerate the hydration the process, promote the formation of hydrated gel product. Metakaolin can reduce the steam curing concrete in Ca (OH) 2 content, reduce porosity and increase the content of C-S-H gel and other products. The release period, mixing 20% metakaolin autoclaved concrete in Ca (OH) 2 is the be the consumption of volcano. The content of Ca (OH) 2 of the steam cured concrete with single mixed 15% metakaolin for 90 d years is only half that of the blank group.

【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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