Gina Matias

Viability of ceramic residues in lime-based mortars

When we approach the subject of construction and rehabilitation of buildings we necessarily must think about external wall coatings as they are the elements more exposed to climate actions, mechanical and environmental conditions and, consequently, the first to be deteriorated and to need rehabilitation. Concerning to the replacement of old plasters and renders, air lime mortars are normally the ones that are more compatible with the existing elements, presenting, however, some limitations due to its slow setting time. As an alternative we may use natural hydraulic lime mortars. We know that brick dust and grains have been widely used in mortars in the past, improving its characteristics, and that actually there are many kinds of ceramic residues that are byproducts of industry and are normally carried into landfills. Within this context and associating the improvement of mortars characteristics to the necessity of sustainable construction practices, some mortars, formulated based on air lime or natural hydraulic lime, with the addition of ceramic residues, have been recently studied. The aim of this paper is to present the experimental work that has been developed concerning the behaviour of two types of these lime mortars with ceramic residues. Characteristics, particularly in terms of flexural and compressive resistances, capillary water absorption and water vapour permeability will be discussed. Comparison will be made between the characteristics of the mortars made with the two limes, and of mortars made with those limes with partial substitutions of siliceous sand by different types of ceramic residues. It will be possible to draw same conclusions about the interest and viability of recycling the ceramic residues as aggregates, its contribution as pozzolan and filler, and also if natural hydraulic lime-based mortars can be a good alternative to air lime-based mortar for ancient masonry.