Natural hydraulic lime mortars for rehabilitation of old buildings: Compatibility and performance

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. For old buildings the balance between functional performance and compatibility requirements is sometimes a demanding issue. The binder defines to a certain point the mortar’s characteristics. Natural hydraulic limes NHL are under the scope of the European Standard EN 459-1:2010 that establishes now rather restrict and clear rules for their composition and characteristics. In this work, results of the characterization of a natural hydraulic lime NHL 3.5 produced in Portugal and of mortars with NHL 3.5 as a binder are presented. Two different sand natures and several proportions lime : sand are used. Results of tests in laboratory and in situ are presented and discussed considering the use of the mortars for rehabilitation of old buildings.