Simulating the effect of microcracks on the diffusivity and permeability of concrete using a three-dimensional model

Abstract

Concrete inevitably contains microcracks, but their significance on transport properties and long-term durability is not well established. This is because of difficulties in isolating and evaluating the effect of microcracks whether by laboratory experiments or computer simulations, owing to their complex heterogeneous nature. In this paper, a three-dimensional numerical approach to simulate mass transport properties of concrete containing microcracks is presented. The approach is based on finite-element method and adopts aligned meshing to improve computational efficiency. The mesostructure of concrete is represented by aggregate particles that are surface meshed by triangulation and porous cement paste matrix that are discretised with tetrahedral elements. Microcracks are incorporated as interface elements at the aggregate-paste interface or at the cement paste matrix spanning neighbouring aggregate particles. The main advantage of this approach is that the smallest microcracks can be simulated independent of the discretisation size. The model was first validated by comparing the simulations to available analytical solutions. Then, the diffusivity and permeability of a range of concretes containing different amounts of microcracking with increasing complexities were simulated. The results are analysed and discussed in terms of the effect of microcrack type (bond, matrix), volume fraction, width, specific surface area and degree of percolation on transport properties.

Transport properties of concrete after drying-wetting regimes to elucidate the effects of moisture content, hysteresis and microcracking

“…Therefore, concretes containing SCMs are more sensitive to severe drying. Furthermore, the effect of drying induced damage is more pronounced for systems with denser matrix in agreement with 3D simulations [48].…”

“…16a). Again, we observe that permeability is most sensitive to damage as was reported in previous studies [9,12,33,48].…”

“…They suspected microcrack closure, but did not provide supporting evidence. Dehghanpoor Abyaneh et al [48] simulated concrete containing microcracks using a three-dimensional mesoscale model. They carried out a sensitivity analysis of the effect of bond and matrix microcracks of varying widths (1-50µm), crack pattern, vol.…”

Elastic constants and homogenized moduli of gypsum structure based on Density Functional Theory

“…As its appreciable advantages such as load-bearing capacity, durability, maneuverability, flowability…, the building materials and their properties have been deeply investigated in the dedicated scientific literatures [1,2,3] . DFT as a first-principles theory and a solid band theory in quantum mechanics has own a great success in linking physical properties and molecular structure, the calculation with exact accuracy but for low computational efficiency for macromolecular structure [4] .…”

An inverse analysis approach for the identification of the hygro-thermo-chemical model parameters of concrete

“…A multi-phase coupled thermochemo-mechanical model was proposed by Gawin [7] and more recently by Du [8] and it accounted for the porous nature of the concrete by considering a micro-scale description of the material. The effects of the 3D meso-structure, modelled with different aggregate particles shapes and porous cement paste matrix, and of microcracks distribution on diffusivity and permeability of concrete materials has been studied in [9] and [10]. A new cement hydration model has been proposed in [11], considering the effects of C-S-H layers forming around anhydrous cement grains to control the very long hydration process which may occur in thick concrete components.…”