Electrical properties of alkali-activated materials against Portland cement

A first attempt was made to study the electrical properties of pastes and mortars prepared from the most common alkali-activated materials against those of Portland cement (PC). The properties included electrical conduction, dielectric constant, the real part of dielectric permittivity and loss tangent factor. The frequencies measured ranged from 100 MHz to 3 GHz. The most common starting materials such as slag, fly ash (FA) and metakaolin (MK) were used and activated with sodium silicate and sodium hydroxide solution to prepare geopolymer pastes and mortars. After curing, the specimens were tested under compression to determine the compressive strength. In addition, electrical properties were measured. The results showed that FA-based geopolymer and PC specimens exhibited similar electrical properties. MK- and slag-based geopolymer specimens also exhibited similar electrical properties but with lower conductivity compared with the other two types. The results also confirmed similar electrical properties of pastes compared to mortars.