Natural hydraulic lime mortars: Performance and field of application

Abstract

Mortars for renders and plasters should verify a number of requirements to be functional and durable, which are related to: compatibility with other materials in the building, especially the substrate; environment and climatic conditions which they are exposed to; required functions in the building. The binder defines to a certain point the mortar’s characteristics: cement mortars exhibit rather high strength and air lime mortars are quite deformable. Hydraulic lime mortars are more difficult to define, because they include a large group of materials, with variable proportions of calcium carbonate and hydraulic compounds and variable calcination temperatures. The European Standard EN 459-1:2010 established more restrict and clear rules for those materials. In this article an experimental campaign on natural hydraulic lime NHL 3,5 mortars is presented. Two different sand natures and several proportions lime : sand are used. Results of tests in laboratory and in situ are presented and discussed. Considerations are made about the impact of the studied factors and about the fields of application of those mortars.