基于陶粒吸水返水特性的轻骨料混凝土性能研究

发布时间：2018-04-29 16:49

本文选题：轻骨料混凝土 + 陶粒　；参考：《福州大学》2013年硕士论文

【摘要】：对不同类型、不同预湿程度的陶粒在总水灰比相同混凝土中的吸水返水特性进行对比分析,研究采用不同类型、不同预湿程度陶粒的轻骨料混凝土的水泥水化程度、孔结构分布和抗压强度,通过各项试验研究对陶粒吸水返水特性进行探讨,提出用于陶粒混凝土性能预测的理论模型,主要的研究方法和成果如下：1.采用容量瓶法和U型管法测得的陶粒在净水中吸水特性具有较好的相关性；采用U型管法测得陶粒在混凝土中的吸水返水特性,发现陶粒掺量对其吸水返水特性的影响很小；当陶粒类型相同时,预湿程度越高,陶粒在混凝土中的吸水能力越弱,返水能力越强；当预湿程度相同时,吸水率大的陶粒吸水能力较强,返水能力也较强。2.利用MATLAB和1stOpt软件,拟合得到关于龄期、吸水率、净水灰比的陶粒吸水返水特性模型,并用前人的试验数据加以验证；根据U型管法所得试验结果,推导混凝土内部有效水灰比随龄期和吸水返水量变化的计算模型。3.采用化学结合水量法对陶粒混凝土的水化程度进行研究,在总水灰比相同的情况下,陶粒吸水率越大、预湿程度越高,水化反应速率越低,水化程度越小,达到最大水化程度所需的时间越长,内部未水化的水泥颗粒也越多。利用1stOpt软件,回归分析并验证了以有效水灰比和龄期等为自变量的陶粒混凝土水化程度计算模型。4.通过氮吸附法对陶粒混凝土的微观结构进行研究,随龄期的延长,大孔体积逐渐减小,凝胶孔体积逐渐增加：在总水灰比相同的情况下,陶粒预湿程度越高,大孔体积越少；平均孔径随龄期的延长而减小,随预湿程度的提高而减小。5.研究了陶粒混凝土抗压强度的变化规律,拟合得到关于水化程度和筒压强度的抗压强度计算模型,与现有的鲍罗米公式相比,本文的公式更适合用于预测轻骨料混凝土的抗压强度。6.基于上述研究,通过研究陶粒在混凝土中的吸水返水特性,可推算出混凝土有效水灰比的变化,用于预测混凝土水化程度、抗压强度等性能的研究。本文选题及研究来源于国家自然科学基金项目,项目名称为“轻骨料混凝土拉伸徐变机理研究”。
[Abstract]:The characteristics of water absorption and water return of different types and different prewetting degree of ceramsite in concrete with the same total water-cement ratio were compared and analyzed. The cement hydration degree of lightweight aggregate concrete with different types and different prewetting degree was studied. The distribution of pore structure and compressive strength are studied. The characteristics of water absorption and water recovery of ceramsite are discussed through various experiments. A theoretical model for predicting the performance of ceramsite concrete is proposed. The main research methods and results are as follows: 1. The water absorption characteristics of ceramsite in clean water measured by capacity bottle method and U-shaped tube method have good correlation, and the water absorption and water return characteristics of ceramsite in concrete are measured by U-shaped tube method, and it is found that the content of ceramsite has little effect on the water absorption and water recovery characteristics. When the type of ceramsite is the same, the higher the prewetting degree is, the weaker the water absorption capacity of ceramsite in concrete is, and the stronger the water return ability is when the prewetting degree is the same, and the water absorption capacity of ceramic grain with large water absorption rate is stronger and the water return ability is also stronger. By using MATLAB and 1stOpt software, the model of water absorption characteristics of ceramsite about age, water absorption rate and ratio of water to cement is obtained, which is verified by previous experimental data, and the test results are obtained by U-tube method. The calculation model of effective water-cement ratio with age and water absorption back water is derived. The hydration degree of ceramsite concrete was studied by chemical combined water method. Under the same water / cement ratio, the higher the water absorption, the higher the prewetting degree, the lower the hydration reaction rate and the smaller the hydration degree. The longer it takes to reach the maximum hydration level, the more unhydrated cement particles are inside. By using 1stOpt software, regression analysis was carried out to verify the calculation model of the hydration degree of ceramsite concrete with effective water-cement ratio and age as independent variables. The microstructure of ceramsite concrete was studied by nitrogen adsorption method. With the prolongation of age, the volume of macropore decreased gradually, and the volume of gel pore gradually increased. Under the same ratio of total water and cement, the higher the prewetting degree of ceramsite was, the less the volume of macropore was. The mean pore size decreases with the increase of age and with the increase of prewetting degree. The variation law of compressive strength of ceramsite concrete is studied, and the calculation model of compressive strength about hydration degree and cylinder compressive strength is obtained by fitting. The formula in this paper is more suitable for predicting the compressive strength of lightweight aggregate concrete. Based on the above research, the change of effective water-cement ratio of concrete can be calculated by studying the characteristics of absorbing water and returning water of ceramsite in concrete, which can be used to predict the hydration degree and compressive strength of concrete. This paper is based on the National Natural Science Foundation of China. The project is entitled "study on tensile creep mechanism of lightweight aggregate concrete".
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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