Non Standard testing of mechanical characterization to support the conservation of old renderings.

Abstract

The knowledge of physical and mechanical characteristics of historic mortars is very important to select repair materials and to plan adequate repair interventions. There is a need to define characterization test methods applicable to irregular, friable samples, with relatively thin layers, in order to assess the main properties. Another relevant issue in that process is the assessment of the new mortars to use for repair, which should be compatible, efficient and durable. Due to the need of compatibility, usually repair mortars must be based on air lime and thus standardized test methods prepared for cement mortars may be inadequate. This article focuses on two non-standard methods for measuring mechanical performance to support conservation interventions of old renderings: a test method to assess the flexural strength of mortar samples with non-standard dimensions is described and its validation process is presented, and a test to determine the tensile bond strength of substitution low strength mortars to a defined substrate is presented and discussed.