Probabilistic study on hydraulic conductivity of concrete at mesoscale

Hydraulic conductivity of concrete can be used as a key indicator in assessment of service life of concrete structures. In this paper, a probabilistic investigation on hydraulic conductivity of concrete is conducted, allowing for variation in hydraulic properties of concrete constituents. Concrete is modeled as a three-phase composite at mesoscale, consisting of mortar, aggregates, and the interfacial transition zone (ITZ). A finite element (FE) method is developed to calculate the hydraulic conductivity of concrete, which is then verified using available experimental results. Based on a large pool of samples generated from Monte Carlo simulation, a conceptual model relating hydraulic conductivity of concrete to aggregate volume fraction ratio and hydraulic conductivity of mortar and the ITZ is proposed. It is shown from the probabilistic-based sensitivity analysis that hydraulic conductivity and thickness of the ITZ are among the most influential factors affecting the bulk hydraulic conductivity of concrete. It is also shown that for high aggregate volume fraction ratios, due to increasing volume of the ITZ, the coefficient of variation of hydraulic conductivity can be as high as 0.36. © 2018 American Concrete Institute. All rights reserved.