REVIEW OF FACTORS AFFECTING THE DURABILITY OF REPOINTING MORTARS FOR OLDER MASONRY

A H P Maurenbrecher¹, K Trischuk², M Z Rousseau³

1. Research Officer, National Research Council Canada (NRC), Institute for Research in Construction (IRC), Ottawa K1A 0R6. Email: paul.maurenbrecher@nrc.ca
2. Technical Officer, NRC, IRC. Email: ken.trischuk@nrc.ca
3. Research Officer, NRC, IRC. Email: madeleine.rousseau@nrc.ca

ABSTRACT

The selection of repointing mortars for older masonry in the Canadian climate is a subject of debate. Repointing mortars should be durable, practical in application (e.g. workmanship, quality control), and not have a negative effect on the durability of the existing masonry. Durability is not only dependent on the mortar mix used but also on how it is installed and cured (workmanship) and on the severity of the environmental exposure, which in turn depends on weather, design, construction, operation and maintenance.

This paper reviews literature dealing with the selection and performance of mortars used in the repair of older masonry. Particular emphasis is given to factors affecting the resistance to frost damage, a major consideration in a cold climate.

Key words: masonry, repointing, mortar, freeze-thaw, durability, heritage.

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