Effects of mineral admixture on concrete mix In Khartoum State, Sudan

Abstract

This research examined the potential of bagasse ash, metakaolin, volcanic ash , rhyolite, ignimbrite and trachy basalt for development as pozzolanic materials in concrete. chemical properties of bozzolanic materials were investigated before and alter increasing the fmeness by grinding. Compressive strength of concrete containing bagasse ash, metakaolin, volcanic ash , rhyolite, ignimbrite and trachy basalt for 10, 20, ands 30% by weight of binder were investigated. The results showed that the compressive strengths of pozzolzanic materials concretes with 10% replacement of tracky basalt and bagasse ash is lower than pure Portland cement concrete in 28 and 60 days but, is greater than it in 90 and 120 days. The volcanic ash and rhyolite 10% blended cement is lower than pure Portland cement in 28 days and greater than it in 60,90 and 120 days. The metakaolin and ignimbrite 10% blended cement strength is greater than pure Portland cement in 28, 60, 90 and 120 days. The tracky basalt, bagasse ash, volcanic ash and rhyolite 20% blended cement strength is lower than pure Portland cement in 28, 6O,and 90 days and greater than a in 120 days. The ignimbrite blended cement strength is greater than pure Portland cement in 28 days, similar to a in 60 days and increased over a in 90 and 120 days. For the metakaolin blended cement strength is greater than pure Portland cement in 28 days, lower than it in 60 days, similar to it in 90 days and greater than it 120 days. All the pozzolanic materials used in 30% blended cement strength is lower than pure Portland cement in 28, 60 and 90 days but greater than it in 120 days. These results approved that the strength of pozzolanic material when used as partial replacement for Portland cement in concrete depended mostly on the grain size , chemical composition and reactivity of pozzolanic material. material used. This suggested that the original pozzolanic materials were suitable to be used as partial replacement of Portland cement up to 30% in concrete. Eight rock samples were evaluated as concrete aggregates, for their strength, water absorption, impact value and alkali reactivity, the results suggested that only tracky basalt and Suliek granite are suitable. The strength of concrete is directly proportional with concrete age.