Hydraulicity and Mechanical Properties of Mortars Manufactured with a Commercial Zeolite

Further to a recent exploratory investigation on the possible use of cheap, commercially available, synthetic zeolites as pozzolanic addition to portland cement, the present study aims at characterizing a low-silica sodium zeolite, named Na-A, as possible component of hydraulic lime mortars. In order to evaluate the action played by the zeolite in developing hydraulicity and mechanical properties, three lime-zeolite mortars with different ratios of the two components were prepared and characterized in terms of compositional features and mechanical and physical properties. The pozzolanic activity of the zeolitic addition was also evaluated by measuring the amount of free lime in experimental pastes, as a function of ageing time. The main results worked out are: (a) zeolite addition gives rise to a clear benefit on compressive strengths of the hardened mortars; (b) hardening is rapid, as more than 60% of the final compressive strengths is developed after only 7 days; (c) lime/zeolite ratio does not affect to a great extent porosity and water absorption of the manufactured mortars; (d) mortars containing equal amounts of lime and zeolite show the best performances, either from a compositional point of view (absence of unreacted zeolite) or from mechanical and porosimetric properties, also in comparison to an analogous, non-zeolitic, commercial mortar.