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首页> 外文会议>First International Conference on Computational Methods in Materials Characterisation; Santa Fe, New Mexico >A 3D study of mortar degradation by X-ray computed microtomography
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A 3D study of mortar degradation by X-ray computed microtomography

机译：X射线计算机断层摄影术对灰浆降解的3D研究

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Prediction of long term performance and durability of concrete is an essential issue for many practical problems. In various situations, the cement paste is attacked by dissolved elements present in the water surrounding the structure and more or less deeply penetrating it. In this work the consequences of leaching, accelerated by ammonium nitrate, on samples of a standard mortar have been characterised in 3D by X-ray computed microtomography (XCMT). This non-destructive method provides quantitative 3D maps of the sample's X-ray absorption coefficient μ. At each voxel (cubic volume element composing the 3D map), the value of μ is the average of the absorption coefficients of the different solids and fluids contained into it at the moment of acquisition. Considered samples are cylinders of 8 mm in diameter and 3 cm in height that have been cored into larger samples of a standard mortar. Microtomography data acquisitions have been performed on the beam line ID 19 at the European Synchrotron Radiation Facility (Grenoble, France). At regular intervals during the leaching process, 900 radiographs of the sample have been acquired at different angular positions using the CCD FRELON camera (2048 x 2048 pixels). With the selected optical set up, the physical size of a pixel is 7.46 x 7.46 μm~2. After numerical reconstruction, the 3D final images are composed of about 1100 x 1100 x 1000 cubic voxels. For each sample, four 3D images corresponding to the initial state, and the states after 24 hours, 48 hours, and 61 hours of leaching, have been registered giving for each voxel an estimation of its chemical evolution. Preliminary treatments put into evidence the macro porosity evolution, the 3D displacement of the reaction front, and allowed a first quantification of calcium release as a function of time and space.
机译：预测混凝土的长期性能和耐久性是许多实际问题的基本问题。在各种情况下，水泥浆会受到结构周围水中存在的溶解元素的侵蚀，并或多或少地深深渗透到其中。在这项工作中，通过X射线计算机显微断层扫描（XCMT）在3D中对标准灰浆样品上硝酸铵加速浸出的后果进行了表征。这种非破坏性方法提供了样品X射线吸收系数μ的定量3D映射。在每个体素（组成3D贴图的立方体积元素）上，μ的值是采集时包含在其中的不同固体和流体的吸收系数的平均值。所考虑的样品是直径8毫米，高3厘米的圆柱体，这些圆柱体已装入标准砂浆的较大样品中。在欧洲同步加速器辐射设施（法国格勒诺布尔）的ID 19射线束上进行了显微断层照相术的数据采集。在浸出过程中，以规则的间隔使用CCD FRELON相机（2048 x 2048像素）在不同角度位置采集了900张射线照相样品。使用选定的光学设置，像素的物理尺寸为7.46 x 7.46μm〜2。经过数值重建后，3D最终图像由大约1100 x 1100 x 1000立方像素组成。对于每个样品，已记录了对应于初始状态以及浸出24小时，48小时和61小时后的状态的四张3D图像，从而为每个体素提供了其化学演化的估计值。初步处理证明了宏观孔隙演化，反应前沿的3D位移，并允许对钙释放随时间和空间的函数进行首次定量。

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