Zeolites from pumice and tuff as evaluation of pozzolanic cement constituents

Zeolites derived from Lipari pumice by hydrothermal synthesis show high pozzolanic activity at variance to those based on tuff. Cement formulations containing 10-20% zeolite have been derived which lead to a low free CaO content (Fratini test) at setting of the concrete and to improved physico-technical properties (in terms of Blaine value, flexural and compression strength). Further zeolite added in excess acts only as an inert. Smaller amounts (5-10%) can be used in pozzolanic cement formulations in conjunction with partial substitution of the clinker with inert siliceous material. © 1985.