Microstructure and durability of slag cement mortars hardened under different relative humidity conditions

Abstract

In recent years the use of active additions on cement, like ground ­granulated blast-furnace slag, has become very popular because they have many environmental benefits. In this work, the behaviour of mortars made with two different cement types, an ordinary Portland cement and a slag cement, was tested. These mortars were exposed to two different environmental conditions during their hardening, an optimum laboratory condition and a Mediterranean climate environment with lower relative humidity. The development of the microstructure of mortars and the changes of their service properties were studied at different hardening ages until 90 days. The mortars made with slag cement have shown a good behaviour compared with ordinary Portland cement mortars. The relative humidity has an influence on properties of both cements studied. As a preliminary conclusion, cements with slag hardened under environmental conditions of a Mediterranean climate, can have good service properties at early hardening ages, even better than Portland cement.