Effect of Compaction Degree on the Carbonation Properties of Steel Slag.

Carbonation technology offers a novel approach to enhance steel slag performance, where the compaction degree plays a pivotal role in optimizing the carbonation process. This study reveals that as the compaction degree increases, the peak temperature in the carbonation environment gradually decreases, and the intensity of the carbonation reaction weakens. Post-carbonating, the compressive strength initially increases before declining, peaking at a compaction degree of 60%. At this optimal compaction degree, the material achieves a compressive strength of 124.4 MPa and a CO uptake of 14.5%. The analysis of pore size distribution and carbonation products reveals that steel slag compacts with lower compaction degrees exhibit larger internal pores, leading to dispersed and isolated carbonation products, which restrict performance improvement. Conversely, excessively high compaction degrees cause the premature blockage of gas diffusion pathways by calcium carbonate particles, which impede the carbonation process and degrade the mechanical performance. The moderate compaction of steel slag effectively prevents the early blockage of gas channels, and significantly facilitates the accumulation and bonding of carbonation products, thereby achieving the superior performance.