Concrete structures are prone to cracking, and these cracks can lead to durability problems and increased maintenance costs. As a result, self-healing concrete has attracted much attention in recent years and has shown great potential to resolve some of these durability issues. Among the various existing self-healing techniques, the biomimetic vascular self-healing system is seen to be one of the most promising and versatile systems [1], and it has been applied to real structures at engineering scale [2].

To better understand the healing mechanisms associated with the system, and to optimise its design, a numerical model of the vascular system is proposed. In this study, the dissipation of the healing agent in and around discrete cracks after being released from the delivering flow network is simulated. This flow process comprises the flow of the liquid in the macro-crack space and the flow into the surrounding porous concrete matrix. The flow in the discrete crack is modelled by a modified Lucas-Washburn (L-W) equation [3], where an additional flow term Q has been introduced to take account of the mass being absorbed by the surrounding matrix. This flow term is determined by a 2D finite element continuum model of the surrounding matrix and is based on isothermal unsaturated flow theories [4]. A mass balance equation is added to account for the interflow between the macro-crack and the matrix. This is achieved by treating the crack as an internal boundary within the matrix and computing the flow across this boundary. The simulation results suggest that imbibition has a significant influence on the flow in the macro-cracks and the degree of influence is related to the permeability as well as to the degree of saturation of the adjacent fracture process zone.