为了揭示碳化反应对水泥砂浆内部缺陷分布的影响规律,采用三维XCT(X-ray computed tomography)对碳化前后的水泥砂浆的三维内部缺陷体积分数和缺陷尺度分布进行了定量分析。通过XCT的配套软件VG Studio MAX 2.0对水泥砂浆内部缺陷的投...为了揭示碳化反应对水泥砂浆内部缺陷分布的影响规律,采用三维XCT(X-ray computed tomography)对碳化前后的水泥砂浆的三维内部缺陷体积分数和缺陷尺度分布进行了定量分析。通过XCT的配套软件VG Studio MAX 2.0对水泥砂浆内部缺陷的投影进行三维重构,并通过配套的三维缺陷分析模块软件从三维图像中提取出水泥砂浆内部缺陷的体积分数和尺度分布。结果表明:三维缺陷尺寸范围为0.03～5.5 mm3,碳化前后的水泥砂浆内部缺陷体积分数分别为2.79%和1.86%。体积小的缺陷减小的比例更大,特别在0.03～0.1 mm3的缺陷体积减小的比例最大。主要原因是水泥砂浆中的氢氧化钙和CSH凝胶碳化反应后生成碳酸钙和水,相同摩尔质量的碳酸钙的体积比氢氧化钙和CSH凝胶都要大,碳酸钙和水填堵并细化了原来的缺陷,导致碳化后水泥砂浆内部缺陷体积分数减小。展开更多
In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomogra...In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomography）is employed to quantitatively analyze the initial defects in four series of highperformance concrete （HPC）specimens with additions of different mineral admixtures. The nigh-resolution 3D images of microstructures and filtered defects are reconstructed by micro- CT software. The size distribution and volume fractions of initial defects are analyzed based on 3D and 2D micro-CT images. The analysis results are verified by experimental results of watersuction tests. The results show that the additions of mineral admixtures in concrete as cementitious materials greatly change the geometrical properties of the microstructures and the spatial features of defects by physical-chemistry actions of these mineral admixtures. This is the major cause of the differences between the mechanical behaviors of HPC with and without mineral admixtures when the water-to-binder ratio and the size distribution of aggregates are constant.展开更多
文摘为了揭示碳化反应对水泥砂浆内部缺陷分布的影响规律,采用三维XCT(X-ray computed tomography)对碳化前后的水泥砂浆的三维内部缺陷体积分数和缺陷尺度分布进行了定量分析。通过XCT的配套软件VG Studio MAX 2.0对水泥砂浆内部缺陷的投影进行三维重构,并通过配套的三维缺陷分析模块软件从三维图像中提取出水泥砂浆内部缺陷的体积分数和尺度分布。结果表明:三维缺陷尺寸范围为0.03～5.5 mm3,碳化前后的水泥砂浆内部缺陷体积分数分别为2.79%和1.86%。体积小的缺陷减小的比例更大,特别在0.03～0.1 mm3的缺陷体积减小的比例最大。主要原因是水泥砂浆中的氢氧化钙和CSH凝胶碳化反应后生成碳酸钙和水,相同摩尔质量的碳酸钙的体积比氢氧化钙和CSH凝胶都要大,碳酸钙和水填堵并细化了原来的缺陷,导致碳化后水泥砂浆内部缺陷体积分数减小。
基金The Scholarship Supported by Ministry of Education of China for Research Abroad(No.3037[2006])the Excellent Doctoral Dissertation Foundation of Southeast University (No.YBTJ-0512)the National Basic Research Program of China(973Program)(No.2009CB623203)
文摘In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomography）is employed to quantitatively analyze the initial defects in four series of highperformance concrete （HPC）specimens with additions of different mineral admixtures. The nigh-resolution 3D images of microstructures and filtered defects are reconstructed by micro- CT software. The size distribution and volume fractions of initial defects are analyzed based on 3D and 2D micro-CT images. The analysis results are verified by experimental results of watersuction tests. The results show that the additions of mineral admixtures in concrete as cementitious materials greatly change the geometrical properties of the microstructures and the spatial features of defects by physical-chemistry actions of these mineral admixtures. This is the major cause of the differences between the mechanical behaviors of HPC with and without mineral admixtures when the water-to-binder ratio and the size distribution of aggregates are constant.
