Properties of Green Cement Concrete with Alternative Cementicious Binders

The need to meet a sustainable development is now an important challenge to the cement industry. The production of OPC is responsible for about 7% of the world’s CO2 emissions, lead to the search for more environmentally viable alternative to cement. Some of those alternative materials are alkali-activated slag (AAS) and fly ash (FA), where AAS and FA are used not as a partial replacement to cement but as a sole binder in the production of concrete. The overall aim is to investigate the potential of mixture of alkali activated slag (100%) and the potential of mixture of alkali-activated slag (60%) + fly ash (40%) as the sole binder in producing concrete. The performance of mixture of alkali activated slag and fly ash as concrete with sodium hydroxide as alkali activator is studied. The activator are used at 4% Na20 (by weight of slag) .The scope of the work covered three mixes: a normal strength OPC control mix, sodium hydroxide activated slag, sodium hydroxide activated fly ash+slag. The fresh concrete properties are studied were the setting time and workability in terms of slump, the engineering properties studied are compression test and split tensile test are measured at 1, 3, 7, 21 and 28 days , flexural strength and punching shear test are measured at at 12 and 28 days. The alkali activated slag + fly ash concrete (AAFS) with sodium hydroxide activator investigated was found to achieve very good workability which was higher or comparable with that of OPC/slag concrete.