Effect of Quarry Dust content on the Properties of Self-compacting concrete

Abstract

Self-compacting concrete (SCC) is a highly flow able and stable concrete that can easily fill its Formwork under its own weight without any compaction and any significant segregation. It has gained wide application in the construction Industry as its use eliminates noise due to compaction among other things on site. Since its Paste requires high viscosity and deformability, its stability and flow ability is achieved by increasing the cement content with some mineral admixtures such as quarry Dust since this is more economical and to avoid problems associated with the use of high content of Portland cement (PC) in SCC. Though quarry Dust has been used to replace PC in normal concrete and SCC, the effect(s) of its content on the properties of SCC is yet to be fully investigated. Quarry Dust (QD) sample, slightly pozzolanic or has low reactivity, obtained from a granite quarry site was tested for the optimum percentage mass replacement of PC by, 0, 10, 20, 30 and 40 % respectively in the study. The mixes containing aforementioned quantity of QD were obtained using a constant w/b ratio of 0.50 and a Super plasticizer (SP) of 2.0 – 2.35 kg/m3 to account for the constant water binder ratio. Also, effect of QD content on the fresh and hardened properties of SCC in terms of setting times, Slump flow ability, passing ability, Water demand of QD, compressive and tensile strengths were studied. The aforementioned parameters were determined by tests conducted on fresh and hardened samples of SCC. Results indicates that QD content in SCC increase the initial and final setting times, at 10 – 20 % QD content its flow-ability was okay and also show strong sensitivity to water demand but at 30 % replacement of PC in SCC, its passing ability is susceptible. A maximum compressive strength of 34 N/mm2 was obtained at 56 days curing age for an optimum partial replacement of 20 % QD content. The test results have shown that QD content has positive effect(s) on fresh and hardened properties of SCC and can optimally replace PC partially at 20 % without any adverse effect on SCC.