Hygrothermal Properties and Behaviour of Concrete

Abstract

Concrete has become irreplaceable for modern building structures while at the same time the number of existing concrete constructions requiring conservation or retrofit measures is continuously rising. It can be shown that moisture is a key factor when service performance and durability issue are concerned. Therefore, the moisture behaviour oc concrete is investigated both by hygrothermal simulation and field tests. Additionally the material properties of concrete necessary for the calculations are determined and evaluated. The results show an abnormal behaviour compared to other building materials when water absorption is involved. There appears to be a self-sealing effect which causes liquid penetration to stop at some distance from the surface when concrete is exposed to rain or ground water for some time. Since this effect causes deviations between experiment and simulation, a tentative solution for the application of hygrothermal models is proposed: concrete components are divided in two layers: one where liquid transport is included and the other where vapour diffusion is the only moisture transport mechanism.