Morphological and chemical influence of calcium hydroxide on the plasticity of lime based mortars

Abstract

The influence of slaked limes (calcium hydroxide) on the fresh mortar properties varies according to morphological and chemical characteristics of the raw material. Until now there have been no sufficient scientific results to describe the parameters of calcium hydroxide that modify the plasticity in mortar systems. The aim of the investigations carried out here is to determine these plasticity regulating parameters. Therefore, several calcium hydroxides from different manufacturers have been analysed. The analyses included characterisation of raw materials and detailed investigations of differently slaked lime and lime putty at different times. Chemical and morphological principles of plasticity have been identi fied. Furthermore, these results have been evaluated by correlation of pilot plant experiments with de fined lime mortars regarding their workability. The resulting material parameters responsible for plasticity are pointed out and distinguished between parameters relevant for plasticity values and those for plasticity development after extended soaking time. © RILEM 2012.