混凝土碳化过程的精细化数值模拟与试验研究

发布时间：2018-05-06 15:01

本文选题：碳化 + 反应动力学　；参考：《东南大学》2015年硕士论文

【摘要】：碳化是导致钢筋混凝土结构服役性能劣化的重要原因,而环境中CD2浓度的增大使混凝土的中性化问题越来越受关注。研究碳化对混凝土结构的影响,对准确预测钢筋混凝土结构的服役寿命具有十分重要的意义。随着混凝土材料向高性能方向发展,粉煤灰等矿物掺合料作为混凝土的重要组成部分,广泛应用于工程结构中。遗憾的是,越来越多的试验结果表明,粉煤灰混凝土,特别是大体积粉煤灰混凝土,抗碳化性能相比普通硅酸盐混凝土而言较差。这对粉煤灰混凝土在工程中的应用提出了严峻的考验。本论文以此为主线,主要研究内容如下：从化学反应动力学的角度出发,根据可碳化物质的质量守恒,以一维扩散方程为基础,建立了偏微分方程组(PDES),并通过Matlab给出了其数值解,进而模拟了二氧化碳在混凝土中的扩散与反应。基于骨料级配理论和孔隙概率密度函数,首先利用Matlab分别完成了混凝土中骨料和孔隙的投放(“数值混凝土”),然后利用Abaqus模拟了二氧化碳在“数值混凝土”中的扩散,并将模拟结果与一维扩散方程的计算结果进行对比。通过粉煤灰混凝土的快速碳化试验,研究了粉煤灰混凝土碳化深度随粉煤灰掺量、养护方式的变化规律,提出了一种弥补粉煤灰混凝土抗碳化能力不足的方法。
[Abstract]:Carbonation is an important reason for the deterioration of service performance of reinforced concrete structures, and the increasing of CD2 concentration in the environment makes the neutralization of concrete more and more concerned. It is very important to study the influence of carbonization on concrete structure and to predict the service life of reinforced concrete structure accurately. With the development of concrete materials to high performance, mineral admixtures such as fly ash, as an important part of concrete, are widely used in engineering structures. Unfortunately, more and more test results show that the carbonation resistance of fly ash concrete, especially the mass fly ash concrete, is worse than that of ordinary silicate concrete. This puts forward a severe test to the application of fly ash concrete in engineering. The main contents of this thesis are as follows: from the point of view of chemical reaction kinetics, according to the mass conservation of carbonable substances, the one-dimensional diffusion equation is the basis. A partial differential equation system (PDEs) is established and its numerical solution is given by Matlab. The diffusion and reaction of carbon dioxide in concrete are simulated. Based on aggregate gradation theory and pore probability density function, the aggregate and pore placement in concrete is accomplished by Matlab (numerical concrete), and then the diffusion of carbon dioxide in numerical concrete is simulated by Abaqus. The simulation results are compared with the results of one-dimensional diffusion equation. Through the rapid carbonation test of fly ash concrete, the change of carbonation depth with the amount of fly ash and the curing mode is studied, and a method to remedy the shortage of carbonation resistance of fly ash concrete is put forward.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

【相似文献】