Combined effect of mineral admixtures and fine aggregate on the mechanical properties of ultrahigh performance concrete

Abstract

The aim of this study was to determine combined effect of mineral admixtures namely fly ash, silica fume as an alternative for cement, and fine aggregate including natural whiter sand (NWS) and finely ground quartz sand as partial replacement of natural river sand (NRS) on the mechanical properties of ultrahigh performance concrete (UHPC) containing steel fiber. Concrete was produced by replacing NRS with 22% upto 100% of NWS consists of particle sizes of 5 to 1800 µm, simultaneously combined with binding materials like fly ash (20, 30 and 40%) and silica fume (5 to 15%) as a substitute for cement in mixtures containing Dramix® 3D steel fiber 65/35 at 100kg/m3, and water curing temperature variation ranging follow ambient temperature from 28-34°C. The results indicated that the NRS was replaced with 100% NWS of 5…1800 µm fraction by weight of NRS, in UHPC containing 20% of fly ash combined with silica fume at the replacement levels of 5 to 15% contributed to improved mechanical properties. Detailed, compressive strength of UHPC obtained values 122, 128, 117, 115.3, and 118.5 MPa respectively. Similar results were also observed for the splitting tensile strength attained at 11.6, 11.9, 11.5, 10.5, 10.2 MPa, respectively, while flexural strength values range between 18.8 to 25.4 MPa. These values higher than compared to that of the NRS reference specimens without containing NWS at 28 days of curing. The achieved experimental results demonstrated that the addition of locally available NWS can be a good substitute for NRS, and therefore, can be effectively used in construction activities, which in turn reduces the depletion on the NRS resources. Furthermore, utilization of by-product materials reduces the carbon footprint of cementitious composites production as well as environmental pollution concerns.