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基于三维XCT对碳化引起水泥砂浆内部缺陷改变的测试和分析

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Abstract:

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-raycomputedtomography)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VGStudioMAX2.0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0.03~5.5mm3,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0.03~0.1mm3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。

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