Lime mortar with mixed in crystallization modifiers to mitigate salt damage

This chapter provides experimental evidence that borax is a promising crystallization modifier for sodium sulfate and that it might mitigate salt crystallization damage when mixed in lime-based mortars. It describes the results of an experimental research investigating the effectiveness of borax as a crystallization modifier for sodium sulfate when borax is added to hydrated lime which undergoes the process of carbonation and the effect of borax on the speed of the carbonation process. Lime-based mortars are chosen as a model system, since they are especially prone to salt crystallization damage due to their limited mechanical strength and bi-modal pore size distribution. Similar crystallization habits were observed in specimens in which borax was added to fresh lime paste and specimens to which a borax solution was added after carbonation of lime. The salt resistance of the additivated mortars will be investigated using an accelerated salt crystallization test.