A mortar research program for the Public Works and Government Services of Canada was initiated in the late 1980's. This research program was a most comprehensive one on the Canadian level; more than 100 mortars were tested in the course of the last decade. Its primary objective was to identify durable repointing mortars which would be practical in their application and compatible with specific traditional stone masonry. For the first time physical and mechanical properties as well as frost resistance have been combined under the same research program. This research program was triggered and managed by practitioners to meet the need of major conservation projects carried out in Canada by the federal government.
This paper presents an overview of the testing program, its performance criteria, and its key results. With respect to preservation standards, this paper provides an overview of the application of testing standards to this research program for repointing mortars in laboratory conditions and in-situ. It highlights situations where standards had to betailored to the preservation needs or developed as new testing procedures.
The most important difficulties of this research program with respect to the development of preservation standards are as follows: 1) as the intent of modern masonry design is often different from traditional masonry, few existing standards are directly applicable; 2) there are no existing testing standards which specifically assess the durability of historic mortars; 3) some tests are too costly to be used in a testing program in practice; 4) excessive time is needed for some existing tests for quality control and site supervision.
Practice currently suffers considerably from the lack of appropriate standards for the testing of traditional masonry mortars. There is a great need for preservation standards and only limited resources to address the situation. A well orchestrated and major collective effort is required to adjust and develop testing standards for the preservation of our masonry heritage.