基于X-ray CT技术研究混凝土内部损伤的研究进展

Research Progress of Concrete Internal Damage Based on X-ray CT Technology

使用X射线断层扫描(X-ray CT)方法可以观测混凝土的内部微观结构并据此分析混凝土的内部损伤,这对研究混凝土材料的性能具有重要意义。CT分辨率高低和试件尺寸大小之间的矛盾以及加载设备的局限阻碍了其在混凝土材料研究中的推广应用。随着CT设备的不断优化,CT用于混凝土的研究逐渐由定性分析发展为定量分析,为进一步研究混凝土材料的性能提供了可靠方法。近五年来,CT用于混凝土的研究由孔的分布、裂缝扩展形态及位置、纤维分布、纤维腐蚀状态等定性分析发展为定量分析。使用CT数据进行定量分析主要有五个方面,一是计算各相在不同条件下的体积,以此分析混凝土损伤变化规律;二是分析孔隙参数,如孔的尺寸、孔径分布、不同孔体积占比等,以此研究孔隙与混凝土损伤之间的关系;三是分析裂缝宽度、体积变化,以此分析混凝土断裂变化规律;四是定量评估纤维在混凝土内部的分散状态及方向,以此研究纤维对混凝土性能的影响;五是基于CT图像构建三维模型进行模拟,获得弹性模量及应力应变分布并与试验结果作对比分析。本文基于孔结构和裂缝变化规律对X-ray CT应用于混凝土材料内部损伤的研究进行综述,对近些年来,特别是近五年的研究现状进行总结,分析X-ray CT用于混凝土研究的优劣势,为混凝土的研究者提供参考。

The internal microstructure and damage of concrete can be observed and analyzed by X-ray CT scanning,which is of great significance for studying the performance of concrete materials. The contradiction between the resolution of CT and the size of the specimen and the limitation of loading equipment hinder the popularization and application of CT in the research of concrete materials. With the optimization of CT equipment,the research of concrete has gradually developed from qualitative to quantitative analysis using CT,which providing a reliable method for research on the performance of concrete materials in the further.In the past five years,the research on concrete through CT has developed from pore distribution,crack propagation shape and location,fiber distribution and fiber corrosion to quantitative analysis. Five quantitative analysis of concrete by CT as follows: firstly,analyze the concrete damage rules by calculating the volume of each phase under different conditions. Secondly,study the relationship between pore and concrete damage by analyzing pore parameters,such as pore size,pore size distribution and different pore volume ratio,etc. Thirdly,study the variation rule of concrete fracture by analyzing the variation of crack width and volume. Fourthly,study the influence of fiber on the concrete properties by quantitatively evaluating the dispersion state and direction of the fibers in the concrete. Finally,build three-dimensional model based on CT images,obtain the elastic modulus and stress-strain distribution and compare with the test results.This paper is reviewed the variation rules of pore structure and cracks about concrete by X-ray CT in recent years,especially in the past five years. The advantages and disadvantages of the application of X-ray CT for studying concrete are analyzed,which can provide references for concrete researchers.