THE INFLUENCE OF POROSITY ON THE BEHAVIOUR IN HUMID ENVIRONMENTS OF MORTARS MADE WITH STEELMAKING SLAGS AND ADDITIVES

Abstract

The behaviour of water absorption by capillarity and the water vapour permeability of masonry mortars with added steelmaking aggregates consisting of steelmaking slags are studied. The steelmaking slags are a mixture of electric arc furnace slag (EAFS) and ladle furnace slag (LFS), for use as bonding mortars in construction and on vertical walls as renderings. In order to improve the properties of the mortars, appropriate additives (water retainer and air entraining/ plasticizer) were added, that change the internal interaction of the blend’s components. As porosity is one of the decisive factors of the investigation, the mortars were analysed by Mercury Intrusion Porosimetry (MIP) and Computerized Axial Tomography (CAT), to determine the distribution and types of pores present in the blends. The results of this study indicate that the joint use of both steelmaking slags and additives give rise to masonry mortars with low water absorption by capillarity index, while water vapour permeability is high, which makes them appropriate for use on facings and in the bonding of external masonry, thus guaranteeing durability over time. Keywords: water absorption by capillary action, water vapour permeability, masonry mortars, steelmaking slags