The influence of calcium content on the mixture of sodium silicate with different additives: Na2CO3, NaOH and AlO(OH)

This paper focuses on the influence of calcium on sodium silicate solutions activated with three additives: sodium carbonate, sodium hydroxide and boehmite. The calcium was added in two forms, calcite sand and slaked lime, as these two materials are widely used to restore historical coatings in Morocco. The aim of this work is to synthesize potential coatings from mixtures of a sodium silicate solution and traditional restoration materials. Several mixtures were synthesized and characterized by XRD, FTIR, SEM and the Vickers hardness test. Primary results demonstrated that lime was a highly reactive component in the mixtures when compared with calcite. Moreover, FTIR showed that the evolution of the Si-O-M band is different for these multiple mixtures. The mixtures composed of calcite, sodium silicate solution and boehmite presented good adherence to fired bricks that are used as masonry elements in historical construction. (C) 2016 Elsevier Ltd. All rights reserved.