Roel Hendrickx

Water transport between mortar and brick: the influence of material parameters

This article deals with the phenomenon of the early water transport between fresh mortar and a dry brick. Two bricks with different transport parameters were considered in combination with two different mortars: a lime hydrate mortar and a cement mortar. Water transport was monitored during the first hour after contact using X-ray imaging and simulated using a commercial control volume (CVM) software tool. Such simulations are made possible by a newly developed method to measure transport parameters of fresh mortars. The amount of water leaving the mortar in 1 h depends mostly on two parameters of the mortar: initial and residual water content. The rate of flow across the interface shows a complex behaviour and is larger for cement mortar and for strongly absorbing brick. The accuracy of simulations is somewhat limited by the importance of over-capillary effects in the bricks near the interface. It appears that this over-capillary water is partly distributed over the brick, and partly reabsorbed by the mortar.