Recycle of steel slag as cementitious material and fine aggregate in concrete: mechanical, durability property and environmental impact.

Using steel slag (SS) as cementitious material and fine aggregate in concrete is an effective and environmental method for SS consumption and cost reduction. In this paper, SS was recycled in large volumes in concrete as partial cementitious material and fine aggregate. The compressive strength and reaction mechanism of cementitious material with different SS powder contents including 20%, 25%, 30%, and 35% were presented. The results indicated that 20% of SS powder improved the compressive strength by 34.57% and the hydration products were ettringite (AFt) and calcium silica hydrate(C-(A)-S–H). Furthermore, the mechanical and durability performance of concrete with SS as fine aggregate were investigated. When the SS substitution rate was 75%, the compressive strength was increased by 37.83%. The volume shrinkage rate and 28d-carbonation depth were reduced nearly by 64% for 90 days and 2.33 mm, respectively. The chloride ion penetration resistance reached the optimal grade Q–V and abrasion resistance was improved by nearly 24%. Along with the reduced CO₂ by 210–294 kg/m³ and the decreased cost by 12.61 USD/m³, it is regarded as an effective method to consume steel slag. As such, this research provided a scientific and systematic basis for the large-scale disposal and utilization of industrial waste residues as well as recycled materials preparation. [ABSTRACT FROM AUTHOR]