The Belgian Building Research Institute (BBRI) is as a research institute often confronted to questions from contractors and architects. One of the issues is the choice of repointing mortars for buildings showing frost damage. Indications for in-situ prepared mortar exist in Technical Information Note (TIN) 208 of BBRI, in and in a guide for restoration. These documents give correlations between the composition of the mortar and its expected compressive strength and information about the ‘mechanical' compatibility between mortar and brick. Recommendations about mortar constituents and proportions are given depending on the frost exposure. These documents however need to be updated taking into account the new approach followed in recently appeared standards for direct durability testing of building materials. The compressive strength as mentioned in does not give a guarantee for durable masonry. Physical properties and other mechanical properties as the adhesion play also an important role. Also information about the performance after direct frost is missing. For bricks, methods exist on Belgian and European level, but for masonry mortars and for combinations of brick-mortar they are missing at both levels. This paper contributes to these topics by the analysis of real cases in comparison with laboratory tests on the same materials (bricks) in combination with recommended prescribed mortars. The test program investigates mainly adhesion properties and frost resistance of bricks, mortars and brick-mortar combinations. Because of the lack of an existing method for masonry mortar, the frost resistance is examined by using European methods existing for bricks or joint mortars (tiles). Their applicability to prescribed mortars was investigated by a comparison between bastard mortars (cement-lime) and common cement mortars. The applied test methods to determine the freeze/thaw and mechanical resistance are explained. Results are discussed and the applicability of these methods is evaluated within this research, for which the building sector shows great interest.
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