Evaluation of injection grouting for structural strengthening of ancient buildings

Ancient buildings frequently need structural consolidation due to problems of the subsoil, weathering of concrete and mortars binding together bricks or stone blocks, and damage induced by earthquakes. One of the major problems of structural consolidation is the compatibility between the original constituents of old walls and the new products that are injected. When hydraulic grouts are used for the above purpose, the amount of water injected inside the walls shuld be as low as possible, while keeping a suitable fluidity of the mixture in order to obtain a good penetration and distribution. Moreover, the injected grouts should not release water soluble salts nor react with them, if they are already present in the wall. Finally, the mechanical behaviour of the new grout should be better not too far from that of the original mortar. The present study was aimed at evaluating injection groutings obtained with different hydraulic binders and aggregates, commonly used or proposed for the structural repair of historic buildings. Chemical, physical and mechanical compatibility with an ideal substrate were evaluated by using different methodologies.