Mechanical properties of masonry repair dolomitic lime-based mortars

Abstract

180 different mortars made with a dolomitic lime and different aggregates were prepared in order to be used in restoration works. This paper focuses on the effect of technological variables on pore structure and mechanical properties of magnesian lime-based mortars. Compressive and flexural strengths of the specimens were discussed according to curing time, binder : aggregate ratios, attributes of the aggregates and porosity, at long-term tests.

A strong increase in the strength of mortars has been found after 365 curing days as compared to 28 curing days. The strength has been mainly attributed to the portlandite carbonation, because no significant changes have been observed in the brucite. However, higher strengths than similar aerial lime-based mortars led us to think of other mechanism which increases the strength: the calcite formation through a reaction of dedolomitization (alkali carbonate reaction, ACR) and the brucite crystallization were discussed.

The pore structure has presented a significant influence on the strength. More binder amounts mean more strength due to the higher values of open porosity, which allows the carbonation process. The aggregate characteristics have been correlated with the strength and porosity. Limestone and angle-shaped aggregates, reducing large pores, cause a strength increment.