Development of high performance carbonatable concrete for steel slag valorization

Abstract

This study presents a high performance carbonatable concrete (HPCC) for the valorization of large volume steel slag. HPCC mix is designed to possess closely-packed particle size distribution, in which steel slag accounts for 90% of the binder. HPCC mix exhibits high flowability with ease of workability. The compressive strength of HPCC mix after appropriate predrying treatment reaches 104.9 MPa and 173.7 MPa, respectively, after 12-hour and 7-day carbonation curing. This can be attributed to the additional densification from the precipitation of carbonation products to the already densified matrix, which can be visually and quantitatively illustrated from the examination of microstructure and pore characteristics, respectively. HPCC mix exhibits negligible moisture absorption which is comparable to ultra high performance concrete (UHPC) mix, indicating high resistance to the ingress of foreign deleterious agents. Moisture absorption of Carbonation-induced deformation of HPCC mix is much smaller in comparison to UHPC mix, and the volume stability of HPCC mix is improved as a result of the consumption of f-CaO and periclase during carbonating. Therefore, HPCC mix is a promising candidate for effective utilization of steel slag while maintaining a high performance.