Use of CO2-active BOFS binder in the production of artificial aggregates with waste concrete powder

This study investigated the possibility of using CO2-active basic oxygen furnace slag (BOFS) as binder for the production of AAs with low-value waste concrete powder (WCP). The effects of curing methods (CO2 and natural air curing) and BOFS dosages on the AAs properties were analyzed. The results showed that BOFS could be successfully used as binder to produce WCP granulated AAs, with attained loose bulk density, crushing strength and water absorption of 1220 kg/m3, 3.6 MPa and 8.6%, respectively. Increasing the BOFS dosage enhanced the crushing strength and decreased the water absorption of AAs. CO2 curing resulted in C-S-H and CaCO3 formation, which contributed to further improving the crushing strength by 30%-109% and decreasing the water absorption by 12–22%. From an environmental perspective, the produced BOFS-WCP granulated AAs activated with CO2 were able to reduce global warming potential by 25% compared with conventional AAs containing 20 wt.% cement as binder.