Influence of ground granulated blast furnace slag on the compressive strength and ductility of ultra high-performance fibre reinforced cementitious composites

The mechanical properties of Ultra High Performance Fibre Reinforced Cementitious Composite (UHPFRCC) is basically influenced by the type of fibres and reactive binders used. Fibres primarily influence the ductility whereas reactive binders influence the compressive strength of UHPFRCC. Among the commonly used reactive binders, Ground Granulated Blast Furnace Slag (SL) with its vitreous nature has the ability of influencing both the compressive strength and ductility of UHPFRCC. This study discussed the microstructure and mechanical properties of six different mixtures made up of 0%, 20%, 40%, 60% 75% and 90% cement replacement of SL. The XRD results indicated that, increased levels of C-S-H and ettringite retard the hydration process leading to lower compressive strength and vice versa. The SL-cementitious composite can achieve a compressive strength of up to 108.1MPa and ductility of up to 1.67% without the use of fibres. The maximum compressive strength and ductility were achieved with 40% SL replacement of cement whereas the minimum compressive strength and ductility were achieved with 60% and 20% SL contents, respectively. Moreover, the optimum mechanical properties (i.e. compressive strength, tensile strength, flexural strength, and tensile strain) were achieved with a 40% SL replacement of cement in the cementitious composite.