页岩陶粒泡沫混凝土性能试验与保温机理研究

发布时间：2018-11-24 17:07

【摘要】：页岩陶粒泡沫混凝土是一种内部存在大量封闭型孔隙的新型轻质保温材料,具有利废、环保、节能、廉价等优异的性能。主要以水泥作胶凝材料,粉煤灰作掺合料,页岩陶粒、陶砂为骨料,加水通过机械搅拌均匀后,再将一定体积的发泡剂加入浆体中,经成型、养护而成。试验以泡沫体积掺量、水胶比(分别为0.35,0.4,0.45,0.5,0.55,0.6,0.65)、粉煤灰掺量(分别为10%、15%、20%、25%、30%、40%、45%)为变量制备页岩陶粒泡沫混凝土,研究了不同变量对陶粒泡沫混凝土28d抗压强度和吸水率的影响,建立各变量与性能之间的数学关系式。在前期试验基础上确定较优配比制备陶粒泡沫混凝土,对其抗压强度、吸水率、抗冻性、干燥收缩等性能进行了研究。制备不同密度等级的页岩陶粒泡沫混凝土,测试不同比重的陶粒泡沫混凝土的孔隙率和导热系数,建立了两者间的数学关系式,并使用螺旋CT技术和扫描电子显微镜研究了页岩陶粒泡沫混凝土气孔分布情况,从宏观、细观、微观等不同层面上分析了陶粒泡沫混凝土的保温机理,建立了陶粒泡沫混凝土等效导热系数的数学模型。在室内试验研究的基础上,优化了陶粒泡沫混凝土施工工艺,对施工现场取样的页岩陶粒泡沫混凝土进行抗压强度、吸水率等性能测试,研究了模拟陶粒泡沫混凝土墙体的热工性能。结果表明:(1)随着实际引入的泡沫体积量增多,陶粒泡沫混凝土干密度、抗压强度逐渐降低,而吸水率不断增大;(2)随着水胶比增大,陶粒泡沫混凝土28天抗压强度不断减小,吸水率不断增大;(3)随着粉煤灰取代量增加,混凝土强度先增大后减小,但吸水率变化不大;(4)试验制备的陶粒泡沫混凝土冻融试验后质量损失和强度损失为1.82%和5.4%,干燥收缩较小;(5)制备的页岩陶粒泡沫混凝土导热系数较小,且与混凝土孔隙率具有密切联系,孔隙率越高,导热系数越小;通过螺旋CT技术和扫描电子显微镜技术分析发现页岩陶粒泡沫混凝土含有大量的气孔,这些气孔与页岩陶粒内部的气孔共同作用,使陶粒混凝土导热系数大幅度降低,从而使材料保温性能较好;(6)基于串联和并联两种热阻网络模型,建立了陶粒泡沫混凝土等效导热系数与孔隙率之间的数学模型,通过实测值与两种等效导热系数数学模型理论值之间的对比发现,两种数学模型的理论值与实测值偏差较小,具有较好的适应性;(7)现场取样的陶粒泡沫混凝土抗压强度为15.21MPa,吸水率为5.49%;模拟陶粒泡沫混凝土墙体热工性能较好,传热系数为1.040 K/(W/(m2·K))。
[Abstract]:Shale ceramsite foam concrete is a new type of lightweight thermal insulation material with a large number of closed pores. It has excellent properties such as waste, environmental protection, energy saving and low cost. Cement is used as cementitious material, fly ash as admixture, shale ceramsite and pottery sand as aggregate. After mixing with water by mechanical mixing, a certain volume of foaming agent is added to the slurry, which is formed and cured. In the experiment, the foam volume ratio, water / binder ratio (0.35%), water / binder ratio (0.35%) and fly ash (0.35%) were used in the experiment. The influence of different variables on the compressive strength and water absorption rate of ceramsite foamed concrete for 28 days was studied, and the mathematical relationship between each variable and its performance was established. On the basis of previous experiments, the optimum proportion of ceramsite foam concrete was determined. The compressive strength, water absorption, freezing resistance and drying shrinkage of ceramic foam concrete were studied. The shale ceramsite foam concrete with different density grades was prepared. The porosity and thermal conductivity of different specific gravity ceramsite foam concrete were measured, and the mathematical relationship between them was established. The pore distribution of shale ceramsite foamed concrete was studied by spiral CT technique and scanning electron microscope, and the thermal insulation mechanism of ceramic foamed concrete was analyzed from macroscopic, microcosmic and microcosmic aspects. The mathematical model of equivalent thermal conductivity of ceramsite foamed concrete is established. On the basis of laboratory test, the construction technology of ceramsite foam concrete was optimized, and the compressive strength and water absorption rate of shale ceramsite foam concrete were tested. The thermal performance of simulated ceramic foamed concrete wall was studied. The results show that: (1) with the increase of foam volume, the dry density, compressive strength and water absorption of ceramsite foam concrete decrease gradually; (2) with the increase of water-binder ratio, the compressive strength and water absorption of ceramsite foam concrete decrease continuously in 28 days, (3) with the increase of the amount of fly ash, the strength of concrete increases first and then decreases, but the water absorption rate does not change much. (4) after freeze-thaw test, the mass loss and strength loss of ceramsite foamed concrete are 1.82% and 5.4% respectively, and the drying shrinkage is small; (5) the thermal conductivity of the prepared shale ceramsite foamed concrete is smaller, and it is closely related to the porosity of the concrete. The higher the porosity, the smaller the thermal conductivity; Through the analysis of spiral CT technique and scanning electron microscope technique, it is found that there are a lot of pores in shale ceramsite foam concrete. These pores act together with the pores in shale ceramsite, and the thermal conductivity of ceramsite concrete is greatly reduced. Thus, the thermal insulation property of the material is better; (6) based on the series and parallel thermal resistance network models, the mathematical model between the equivalent thermal conductivity and porosity of ceramsite foamed concrete is established. The comparison between the measured values and the theoretical values of the two kinds of equivalent thermal conductivity models is made. The deviation between the theoretical value and the measured value of the two kinds of mathematical models is small and has good adaptability. (7) the compressive strength and water absorption of ceramsite foam concrete are 15.21 MPA and 5.49 respectively, and the thermal properties of simulated ceramsite foam concrete wall are better, with a heat transfer coefficient of 1.040 K / (m ~ 2 K).
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.2

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