Effect of grounded blast furnace slag and rice husk ash on performance of ultra-high-performance concrete (UHPC) subjected to impact loading

This paper investigates the effect of using alternative cementitious constituents on the compressive performance of Ultra-High-Performance Concrete (UHPC) for both static and dynamic conditions. The grounded blast furnace slag (GBFS) and rice husk ash (RHA) with different portions were used to replace 30% ordinary Portland cement (OPC) of a reference mix (UHPC-R1). Two alternative UHPC mixes including an UHPC mix with 30% GBFS mix (UHPC-AC1) and an UHPC mix with 15% GBFS and 15% RHA mix (UHPC-AC2) were considered. The quasi-static compressive strength and dynamic compressive strength of the proposed UHPC mixes were then determined using a compression testing machine and a Split Hopkinson Pressure Bar, respectively. The results indicated that UHPC-AC1 and UHPC-AC2 yielded a comparable performance compared to the reference mix UHPC-R1. In particular, the static compressive strength of UHPC-AC1 and UHPC-AC2 mixes were found to only be 5% and 10% less than those of the UHPC-R1 mix, respectively. In addition, the study also found that UHPC-AC1 and UHPC-AC2 achieved a similar dynamic compressive strength compared to the UHPC-R1, and the compressive strength of UHPC-AC1 and UHPC-AC2 were not strain rate sensitive. For the environmental aspect, UHPC-AC1 and UHPC-AC2 have a lower embedded CO2 emission index compared to the reference UHPC-R1.