The Influence of Particle Size and Structure in Hydrated Lime on the Properties of the Lime Putty and Lime Mortar

Magazine article, 2010

In this work, scanning electron microscopy (SEM) analysis of lime slaked in different ways and analysis of thin section of lime putty and mortar specimens by light microscopy was combined with practical tests and field studies to evaluate the impact of the slaking technique on the properties of the lime putty as well as the structure of the fresh and carbonated mortar. The lime slaking methods studied were wet slaking and earth slaking, giving lime putties with very different consistency and workability. The aim of this work was to use microscopy techniques to explain these differences in properties and to investigate if it is possible to use these analytical methods to recognize the lime-slaking technique used in a historical lime mortar. The results obtained by SEM show significant differences in structure between the lime putties. The earth-slaked lime consists of relatively large particles that are packed in a porous system compared with the wet-slaked lime with very small particles closely packed in a dense structure. After storing, the wet-slaked lime gives a putty that has a dense and clearly defined stratified structure, whereas the earth-slaked lime is porous and has no stratification.