泡沫混凝土复合板制备中的关键问题研究

发布时间：2018-06-02 22:52

本文选题：泡沫混凝土 + 复合板　；参考：《华南理工大学》2015年硕士论文

【摘要】：为了适应现代建筑中节能、防火、环保等的要求,具有相关优点的无机保温材料日益成为现代建筑节能材料发展的重要方向。其中,泡沫混凝土具有轻质、保温隔热、隔音、不燃和抗震等优良特性,可较好地满足建筑节能和提高建筑安全性的要求,成为现代建筑节能研究的热点。但由于其强度低、易粉化、干燥收缩大等缺点,制约了其在墙体材料领域的应用。为了解决这些问题,本研究采用泡沫混凝土和硅钙板进行复合,开发具有保温、防火等功能的泡沫混凝土复合墙板,围绕泡沫混凝土复合墙板在制备过程的泡沫混凝土粉化问题,泡沫混凝土与硅钙板的粘结问题,泡沫混凝土及硅钙板的不一致干燥收缩导致开裂问题等关键问题展开研究,主要的内容包括:首先,采用外观比较和铅笔硬度法测试了不同泡沫混凝土的粉化程度,通过研究不同容重泡沫混凝土水化产物的组成,探讨超轻泡沫混凝土粉化的机理,进而提出改善泡沫混凝土的粉化现象的措施。结果表明:泡沫混凝土早期快速失水是导致其粉化的主要原因,水分快速蒸发延缓下一步水化,使水化产物含量降低,难以形成良好的凝胶结构,致使部分粉体颗粒容易脱落,形成粉化。泡沫混凝土容重越低,早期失水率越高,粉化越严重,300kg/m3的泡沫混凝土成型初始1d失水率超过40%;加强早期养护、提高水灰比或掺入保水剂,可降低泡沫混凝土的粉化程度。其次,探索了泡沫混凝土的容重、水灰比、乳胶粉掺量及硅钙板的不同处理方式等因素对复合板粘结强度的影响。结果表明:乳胶粉可以明显提高泡沫混凝土对硅钙板的粘结强度,以500kg/m3泡沫混凝土为例,相对于不掺乳胶粉的泡沫混凝土,当乳胶粉掺量为1%时,其压剪粘结强度从178k Pa增加到280k Pa;硅钙板吸收泡沫混凝土浆体中的水,可以提高复合板的粘结强度,但是硅钙板吸水会造成泡沫混凝土消泡塌模。当用相对含水率为50%的硅钙板制备复合板时,可以保证复合板具有较高的粘结强度,同时复合板具有较低的塌模程度。增稠剂可以提高复合板中泡沫混凝土的浇注稳定性,同时保证复合板具有较高的粘结强度。最后,对复合板干燥收缩行为进行了有限元模拟分析,获得复合板内部应力分布情况。对比了乳胶粉、细河砂和聚丙烯纤维对泡沫混凝土的力学性能、干燥收缩和开裂性能的影响。结果表明:聚丙烯纤维的掺入显著地提高了泡沫混凝土的韧性,同时也降低了泡沫混凝土的干燥收缩,掺入细河砂和聚丙烯纤维可将500kg/m3泡沫混凝土干缩值降低至3750×10-6,减轻了泡沫混凝土的开裂程度,纤维是抑制泡沫混凝土开裂的关键因素。以容重为500kg/m3的泡沫混凝土制备复合板,采用聚丙烯纤维对泡沫混凝土进行增韧阻裂,可以提高复合板的抗裂能力,保证复合板结构的完整性。
[Abstract]:In order to meet the requirements of energy saving, fire prevention and environmental protection in modern buildings, inorganic thermal insulation materials with relative advantages have become an important direction in the development of energy saving materials of modern buildings. Among them, foam concrete has the advantages of light weight, heat insulation, sound insulation, non-combustion and seismic resistance, which can meet the requirements of building energy conservation and improve building safety. It has become a hot spot in the research of modern building energy conservation. However, its low strength, easy pulverization and large drying shrinkage restrict its application in the field of wall materials. In order to solve these problems, the foam concrete composite wall board with thermal insulation and fire resistance was developed. The key problems such as the powdering of foamed concrete, the bonding between foamed concrete and calcium silicate slab, and the cracking caused by inconsistent drying shrinkage of foamed concrete and calcium silicate slab are studied. The main contents are as follows: firstly, the powdering degree of different foam concrete is tested by using appearance comparison and pencil hardness method, and the mechanism of ultralight foam concrete powdering is discussed by studying the composition of hydration products of foam concrete with different bulk density. Furthermore, the measures to improve the powdering phenomenon of foamed concrete are put forward. The results show that the rapid water loss in the early stage of foamed concrete is the main cause of its pulverization. The rapid evaporation of water slows down the hydration in the next step, reduces the content of hydration products, and makes it difficult to form a good gel structure, which causes some powder particles to fall off easily. Form a powder. The lower the bulk density of foamed concrete is, the higher the rate of water loss in the early stage is, and the more serious the pulverization of foamed concrete is, the more serious the water loss rate of foamed concrete is 300 kg / m ~ 3 in the first day, the water loss rate of foamed concrete is more than 40% at the beginning of forming. Secondly, the effects of bulk density, water / cement ratio, latex powder content and different treatment methods of calcium silicate plate on the bond strength of composite concrete were explored. The results show that the adhesive strength of foam concrete to calcium silicate slab can be improved obviously by latex powder. Taking 500kg/m3 foam concrete as an example, compared with foam concrete without latex powder, when the amount of latex powder is 1%, The compressive shear bond strength is increased from 178kPa to 280kPa.The silica calcium plate absorbs water from the foam concrete paste, which can improve the bond strength of the composite slab. When the composite plate with 50% relative moisture content is used to prepare the composite plate, it can ensure that the composite plate has higher bond strength and lower collapsing degree. The thickening agent can improve the pouring stability of foam concrete in the composite slab and ensure the high bond strength of the composite slab. Finally, the drying shrinkage behavior of composite plate is simulated by finite element method, and the stress distribution inside the composite plate is obtained. The effects of latex powder, fine river sand and polypropylene fiber on the mechanical properties, drying shrinkage and cracking properties of foamed concrete were compared. The results showed that the toughness of foamed concrete was significantly improved by adding polypropylene fiber, and the drying shrinkage of foamed concrete was also reduced. The dry shrinkage value of 500kg/m3 foam concrete can be reduced to 3750 脳 10 ~ (-6) by adding fine river sand and polypropylene fiber, and the crack degree of foam concrete can be alleviated. Fiber is the key factor to restrain the crack of foam concrete. The composite slab made of 500kg/m3 foam concrete and toughened and cracked by polypropylene fiber can improve the crack resistance of the composite slab and ensure the integrity of the composite slab structure.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.7

【参考文献】