| Abstract: |
Self-compacting concrete (SCC), developed first in Japan in the late 1980s, represents one of the most significant advances in concrete technology in the last twodecades. SCC was developed to ensure adequate compact ion through self-consolidation and facilitate placement of concrete in structures with congested reinforcement and inrestricted areas. SCC can be described as a high performance material which flows under its own weight without requiring vibrators to achieve consolidation by complete filling of the formworks even when access is hindered by narrow gaps betweenreinforcement bars .The high flowability of SCC makes it possible to fill the formwork without vibrat ion.In this thesis, cement has been replaced by fly ash (FA) in various proportions,10%,20%,30%,40%,50% and 60% or silica fume (SF) in proportions of5%, 10% and15% or combination from FA and SF by the proportions 25%F A +5%SF,20%FA+I0°/’)SF+ and 15%FA +15% SF. A control mix without any additives was also prepared for comparison. Fresh properties based on the results of slump flow, L-box and V-funnel tests were measured while hardened properties based on the compressive strength, indirect tensile strength and flexural strength were measured. The compressivestrength was measured at 28, 56, 90 and 270 days while the indirect tension and flexural strengths were measured at 28 days. Both FA and SF were used as a partial replacement of the cement content with different percentages keeping the total cernentitiousmaterials at 400 kg/m’. Several trial mixes of SCC were planned for this purpose in order to select the optimum mix proportions of the mixes.Test results showed that, self compacting concrete can be produced and satisfies the general requirements of the different codes of practice by adding fly ash or silica fume or combination of them. The maximum compressive, tensile and flexural strengths were achieved at fly ash percentage of 20 %. All mechanical strengths of the investigated SCC increased with the addition of silica fume LIp to 15%. The maximumcornpressive, tensile and flexural strengths were obtained at 20% fly ash + I 0% silicafume. The cornpressive strength of SCC incorporating different percentages of fly ash, silica fume or combination of them increased with age.
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