Abstract
This thesis describes an investigation of the various properties of cement paste and concrete mixes incorporating slag as an ordinary Portland cement (OPC) replacement material. Two types of slag were used; a non-commercial air-cooled Electric Arc Furnace Steel Slag produced in Libya (LSS) and a widely used Ground Granulated Blastfurnace Slag (GGBS). The influence on these properties of curing in a Mediterranean (hot, humid) environment or a normal (fog room) environment was investigated. Finally, the feasibility of improving the properties under investigation by incorporating commercially available chemical activators was assessed. The early age (12-hour) reactivity of the GGBS and LSS particles was found to be lower than that of the OPC. However, with increasing age and curing temperature, the reactivity of the GGBS and LSS particles increased, leading to the formation of a greater volume of hydration products, thus reducing porosity and permeability and increased compressive strength in the long-term. The LSS particles were found to be less reactive than those of GGBS over the time scale investigated. This low reactivity can be attributed to the relatively low glass content and the presence of large particles in the LSS. The investigation concluded that mixes containing 30% or 50% GGBS or LSS as an OPC replacement favour hot, humid curing, whereas mixes containing 90% or 100% OPC favour fog room curing at 20°C. No benefit was found when chemical activators where incorporated in mixes containing OPC. However, 100% GGBS mixes activated with 3% Sodium Silicate and 4% lime achieved a significant proportion of their ultimate compressive strength and microstructural properties within a short time period when compared to the 100% OPC control mix. In contrast, the less reactive 100% LSS activated mixes generally produced less favourable properties.