Experimental applications of mortars with pozzolanic additions: Characterization and performance evaluation

Old fortresses near the coast of Lisbon have been originally rendered with very durable lime mortars, sometimes showing pozzolanic reactions (Silva A. Caracterização de argamassas antigas – casos paradigmáticos (in Portuguese). Lisbon: LNEC; October 2002. Cadernos Edifı´cios, No. 2. p. 87–101; Pinto J, Silva A. Lime mortars with pozzolans. The S. Julião da Barra and Ericeira case studies (in Portuguese). In: 3rd ENCORE, Encontro sobre Conservação e Reabilitação de Edifı´cios. Lisbon: LNEC; May 2003), but their very severe environmental conditions – salty atmosphere and sea water close to foundations and walls, mechanical action of the waves, hot sun and temperature variations, strong wind – and also some lack of knowledge concerning maintenance and conservation techniques, produced the deterioration of these renders and the need for their substitution.The best options were thought to be lime mortars with pozzolanic additions.Because of the lack of experience with modern pozzolanic mortars on sea environment, it was decided to carry out experimental applications on one of the Fortresses’ walls of renders with different pozzolanic additives and of some comparison mortars with known performance. Tests were carried out in situ and in laboratory and one of the formulations was chosen for application as a substitution render of the Fortress’s walls.