Influence of curing conditions on lime and lime-metakaolin mortars

Comunicação apresentada ao XII DBMC - International Conference on Durability of Building Materials and Components, Porto, April 12th-15th, 2011Air-lime mortars with or without pozzolanic components were largely used in historic buildings. Due to natural or accidental degradation it is often necessary the application of repair mortars, durable and compatible with the masonries of historic buildings. Within this context and associating the improvement of mortars characteristics to the necessity of sustainable construction practices, some mortars formulated with lime and the addition of pozzolans have been studied. In previous papers, the influence of some types of air-lime (powder hydrated lime or lime putty) and the addition of metakaolin in lime mortars have been presented. Each type of mortar presents its specificities. In pure lime mortars the setting occurs by carbonation and in lime-metakaolin mortars it occurs both by carbonation and hydration. A crucial question in order to optimize the characteristics of the mortars (and its applicability) is related with the curing conditions. This article describes an experimental campaign with different pure air lime mortars and lime-metakaolin mortars, cured under different conditions of relative humidity and CO2 content. Properties of the mortars, mainly in terms of mechanical behaviour and open porosity, capillary water absorption and drying capacity, are obtained, compared and discussed. The benefits in some properties revealed by the different mortars are correlated with the laboratorial curing conditions and with in situ applications possibilities