Numerical Analysis of Concrete Composites at the Mesoscale Based on 3D Reconstruction Technology of X-ray CT Images

A numerical analysis of concrete composites at the mesoscale based on three-dimensional (3D) reconstruction technology of X-ray computed tomography (CT) images is presented in this paper. For X-ray CT images of concrete, morphology processing was used to recover complete image information, including borders, and the median filtering method was applied to eliminate potential impurities in the images. The final X-ray CT images obtained after processing for a concrete section were composed of three-value pixels that indicated aggregate particles, mortar matrix and air voids, and the 3D structure of the concrete specimen was reconstructed using the volume data method. The mapping mesh method was used to identify element material attributes, and a four-point bending-tension fracture process for the specimen was performed. The numerical results show that the load-displacement curve and failure crack location from the reconstructed model were similar to those from the experiment. The damage development for each phase of material obtained from the numerical results indicates that crack initiation occurs in the interface transition zone (ITZ); one macro crack is formed at final failure, and it is caused by the growth and propagation of the micro cracks.