Abstract
Damage initiation and crack propagation in concrete are associated with localisation of energy dissipation by the concrete meso-structure. Meso-scale models are, therefore, required for realistic analysis of concrete non-linear behaviour. Such models are constructed either from X-ray Computed Tomography images (image-based modelling) or by in silico meso-structure generation (parametric modelling), while both approaches are widely used and their advantages and disadvantages are recognised, little work is done on comparing their performance in predicting measured macroscopic behaviour with equivalent constitutive relations for meso-structural features. This work uses microstructure characterisation and mechanical behaviour data to construct, validate and compare the two modelling approaches. The macroscopic behaviour obtained with both meso-structural models is found to be in good agreement with experimental data. Differences are observed only between the predicted distributions of damage within specimens. These outcomes suggest that the computationally simpler parametric meso-structures are sufficient to derive stress–strain behaviour for engineering-scale models in the absence of other environmental factors. The observed differences in damage distribution could be important for analysis of coupled behaviour, e.g., mass transport and chemical reactions affecting local mechanical properties and being affected by local damage. Establishing the importance of damage distribution is such cases requires further research.
Highlights
The macro-cracks of concrete are developed through micro-crack initiation, propagation and coalescence
Interfacial transition zone (ITZ) has lower stiffness and strength compared with mortar, because it is a thin layer of higher-porosity mortar coating around aggregates with thickness between 10 and 100 μm [1,2]
The 2D images obtained from X-ray computed tomography (XCT) can be processed and reconstructed into a 3D model, which can be further meshed in the commercial software Simpleware [6] or self-developed algorithm [5,7]
Summary
The macro-cracks of concrete are developed through micro-crack initiation, propagation and coalescence. The 2D images obtained from XCT can be processed and reconstructed into a 3D model, which can be further meshed in the commercial software Simpleware [6] or self-developed algorithm [5,7]. The latter approach is to generate coarse aggregates synthetically based on given size distribution. This can be achieved by take-and-place method [8,9,10,11,12] and Voronoi tessellation method [13,14,15,16,17]. In the process of placing aggregates, they can be translated and rotated randomly in order to achieve a high aggregate volume fraction (e.g., >50%) [18,19]
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