Case study on production of self compacting concrete using white cement by pass dust

Large quantities of white cement bypass dust (WCBPD) are accumulated annually as a by-product of Jordan white cement manufacturing; representing an environmental threat and a disposal financial burden. The outcome of an experimental study to investigate the potential of using this dust in producing self-compacting concrete (SCC) for structural purposes is reported. SCC mixtures were prepared at a constant water-to-binder ratio of 0.45 using five different replacement percentages of cement by WCBPD ranging from 10 to 25% (by cement weight) with partial replacement of fine limestone aggregate by crushed stone dust. Fresh and hardened properties were investigated to establish the significance of dust use in SCC. The fresh properties of the SCC mixtures were determined by slump flow, V-funnel, and L-Box test. Tests on hardened SCC included compressive strength, internal pore structure in terms of ultrasonic pulse velocity and capillary porosity, dry shrinkage expansion, and durability against alkali-silica reaction. SCC mixes demonstrated acceptable resistance to segregation, with satisfactory passing and filling abilities. Use of WCBPD had significantly contributed to reducing alkali-silica reaction expansions by as high as 44%. The different tests indicated the use of WCBPD at levels below 10% would not undermine strength or durability, maintain acceptable volume stability, and impart improvement to resistance against ASR. Furthermore, the study revealed that concrete for structural application with compressive strengths greater than 40 MPa can be produced at 25% WCBPD replacement of cement by mass.