Physical, mechanical, thermal and sustainable properties of UHPC with converter steel slag aggregates

This paper aims to utilize converter steel slag aggregates (SSA) to develop sustainable ultra-high performance concrete (UHPC) for multifunctional applications. UHPC mixtures with different particle sizes and contents of SSA are developed by applying a modified packing model. The physical, mechanical, thermal and sustainable properties of the designed UHPC have been explored by analysing bulk density, ultrasound pulse velocity (UPV), water-permeable porosity, mechanical strength, spalling and residual strength after elevated temperature, binder efficiency and heavy metal ions leaching. The results show that the optimized particle distribution of converter SSA up to 5.6 mm could be introduced in sustainable UHPC with high 28-days compressive strength up to 177.8 MPa and low binder content as low as 567.2 kg/m3. The designed UHPC mixtures attain bulk density and UPV up to 3070 kg/m3 and 5236 m/s, respectively, which makes them suitable to be utilized as heavy-weight concrete in the protective shield against nuclear radiation. No obvious explosive spalling and relatively high residual strengths reveal the potential application in heat or fire-resistant concrete. The converter steel slag in form of aggregates in UHPC does not cause negative environmental impacts on CO2 emission and heavy metals pollution, considering the relatively high binder efficiency (0.178–0.313 MPa/(kg/m3)) and non-detectable leaching of B, Cr and V.