  Architectural conservation and repair are becoming increasingly important
issues in many countries due to numerous prior improper interventions,
including the use of inappropriate repair materials over time. As a result, the
composition of repair masonry mortars is now being more frequently addressed in
mortar research. Just recently, for example, it has become apparent that
Portland cement mortars, extensively exploited as repair mortars over the past
few decades, are not suitable for repair because of their chemical, physical,
mechanical, and aesthetic incompatibilities with original materials. This paper
focuses on the performance of various lime-based alternative materials intended
for application in repairing historic structures when subjected to mechanical
loading. Results of basic material tests indicate that the use of metakaolin as
a pozzolanic additive produces mortars with superior strength and sufficiently
low shrinkage. Moreover, mortar strength can be further enhanced by the
addition of crushed brick fragments, which explains the longevity of Roman
concretes rich in pozzolans and aggregates from crushed clay products such as
tiles, pottery, or bricks. An integrated experimental-numerical approach was
used to identify key mortar parameters influencing the load-bearing capacity of
masonry piers subjected to a combination of compression and bending. The
simulations indicate increased load-bearing capacities for masonry piers
containing metakaolin-rich mortars with crushed brick fragments, as a result of
their superior compressive strength.
