超轻泡沫混凝土制备及性能研究

发布时间：2018-03-30 20:06

本文选题：普通硅酸盐水泥　切入点：超轻泡沫混凝土　出处：《西南科技大学》2015年硕士论文

【摘要】：超轻泡沫混凝土因孔隙率高、绿色、安全、防火等优点在建筑保温领域发展迅速,目前主要以早强、快凝的特种水泥为胶凝材料,采用化学发泡工艺制成。特种水泥资源匮乏、成本高、耐久性存在问题,化学发泡工艺适合预制件生产,而物理发泡工艺既适合预制又适合现浇,但超轻泡沫混凝土存在强度低、料浆易塌模等问题。为了解决上述问题,本文结合物理发泡工艺,开展了以普通硅酸盐水泥为主要胶凝材料,干密度小于300kg/m3的超轻泡沫混凝土制备与性能研究。研究了促凝剂改性的普通硅酸盐水泥料浆流变性能、早期絮凝结构发展及以该料浆制备的超轻泡沫混凝土料浆的稳定性。在此基础上,研究了配合比、矿物掺合料对超轻泡沫混凝土性能的影响,并探讨了养护制度对超轻泡沫混凝土力学性能的影响。最后,在开展超轻泡沫混凝土吸水、收缩及干缩的研究后,测试了超轻泡沫混凝土的抗冻融及抗碳化性能。研究结果表明:增大促凝剂掺量、降低水灰比与减水剂掺量对改善水泥浆体流变性能不利,但能促进浆体早期絮凝结构发展,有利于制备不塌模的超轻泡沫混凝土料浆;增大促凝剂掺量、干密度与泡沫剂浓度,降低泡沫密度与矿物掺合料掺量导致气孔不同程度变小,而在一定范围内增加减水剂掺量可减小气孔,泡沫裂化时间越长越不利于改善气孔均匀性;采用普通硅酸盐水泥为胶凝材料,促凝剂与减水剂掺量为4%与0.6%,水灰比为0.9时,干密度为2 0 6.0 k g/m3的试样,56d抗压强度为0.51MPa,导热系数为0.0455W/(m·K),水灰比为0.8,可制备出干密度为109.1kg/m3与272.8kg/m3,56d抗压强度分别为0.12MPa与0.75MPa,导热系数为0.0363W/(m·K)与0.0632W/(m·K)的试样;偏高岭土取代20%的水泥可将干密度为180.4 kg/m3的试样56d抗压强度提升到0.65MPa,导热系数达到0.0525W/(m·K);自养护对强度提升有利;硬脂酸钙有利于改善试样防水性能,聚丙烯纤维、减缩剂、轻骨料对超轻泡沫混凝土干缩有一定的抑制作用,减缩剂、憎水剂、聚丙烯纤维复合能够制备出干密度175.0kg/m3,具有一定的抗冻及抗碳化能力的超轻泡沫混凝土。
[Abstract]:Ultra-light foamed concrete has developed rapidly in the field of building heat preservation because of its high porosity, green, safety, fire resistance and so on. At present, it is mainly made of special cement with early strength and quick solidification, which is made by chemical foaming technology. The special cement resources are scarce. High cost, durability problems, chemical foaming process is suitable for the production of prefabricated parts, while physical foaming process is suitable for precast and cast-in-place, but ultra-light foamed concrete has problems such as low strength, easy sloughing of slurry, etc. In order to solve the above problems, Combined with physical foaming process, the preparation and properties of ultra-light foamed concrete with ordinary Portland cement as the main cementing material and dry density less than 300kg/m3 were studied in this paper. The rheological properties of ordinary Portland cement paste modified by coagulant were studied. The development of early flocculation structure and the stability of ultra-light foamed concrete slurry prepared by the slurry were studied. The effects of mix ratio and mineral admixture on the properties of ultra-light foamed concrete were studied. The effects of curing system on the mechanical properties of ultra-light foamed concrete are discussed. Finally, after the study of water absorption, shrinkage and dry shrinkage of ultra-light foam concrete, The freezing and thawing resistance and carbonation resistance of ultra-light foamed concrete are tested. The results show that increasing the amount of coagulant, reducing the ratio of water to cement and the amount of water reducing agent are not good for improving the rheological properties of cement paste, but it can promote the development of early flocculation structure of cement paste. It is beneficial to the preparation of ultra-light foamed concrete slurry without sloughing, increasing the content of coagulant, dry density and foaming agent concentration, decreasing foam density and mineral admixture content, causing the porosity to become smaller in varying degrees. However, increasing the amount of water reducing agent in a certain range can reduce the porosity, and the longer the foam cracking time is, the less the porosity is, and when the cement is used as the cementing material, the ratio of accelerator and water reducer is 4% and 0.6, and the ratio of water to cement is 0.9. When the dry density was 206.0k g/m3, the compressive strength was 0.51MPa, the thermal conductivity was 0.51 MPa, and the water-cement ratio was 0.8.The samples with dry density of 109.1kg/m3 and 272.8kg / m356d were 0.12MPa and 0.75MPa, respectively, and the thermal conductivity were 0.0363W/(m K and 0.0632W/(m K, respectively. Replacing 20% of cement with metakaolin, the compressive strength of the sample with dry density of 180.4 kg/m3 can be increased to 0.65 MPA in 56d, and the thermal conductivity is up to 0.65 MPA. The self-curing is beneficial to the improvement of strength, and calcium stearate can improve the waterproof property of the sample, polypropylene fiber, reducing agent, etc. Lightweight aggregate can inhibit dry shrinkage of ultra-light foamed concrete. Shrinkage reducer, hydrophobic agent and polypropylene fiber composite can produce ultra-light foam concrete with dry density of 175.0 kg / m ~ (3), which has the ability of anti-freezing and anti-carbonization.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.2

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