Influence of water/cement ratio on the properties of fresh SCC with fly ash addition

Abstract

Self-compacting concrete (SCC) exhibits increased flowability in comparison with the conventional vibrated concrete. This is most often achieved through the incorporation of high amounts of extra-fine particles (i.e. mineral fillers) in the composition of self-compacting concrete. The purpose is to limit the share of cement while reaching the required large paste content. The components and their proportions, as well as type and particle size of filler, casting, manufacturing and curing conditions of SCC, significantly influence the concrete’s fresh and hardened properties. Among fillers employed in SCC, fly ash is one of the most frequent due to its availability and the low cost. Fly as is an industrial by-product and a highly efficient mineral additive whose role is reflected in improvements of microstructure packing, strength and durability of non-shaped composite building materials such as self-compacting concrete. A comparative study of performances of SCC with different quantities of fly ash and standard SCC with limestone filler was conducted in this study. The experimental program included the production of reference self-compacting concrete based on Portland cement and limestone filler (P1) and additional three experimental self-compacting concrete mixtures (P2, P3, P4) with different quantities of fly ash addition. Behaviour of self-compacting concrete in the fresh state is primarily influenced by type of mineral additive used. The effect that fly ash addition has on the physical behaviour and mechanical properties of fresh experimental SCC concrete samples was discussed. The properties and technology of self-compacting concretes in their fresh state in regard to the alternations in water/cement (w/c) ratios are monitored and explained in this paper. Concrete mixtures with fly ash had lower density in comparisons with the referent concrete. For the same class of consistency, higher amount of water was needed for preparation of SCC mixture with fly ash. Increasing w/c ratio induced more favourable properties of self-compacting concrete in its fresh state.