Recycled Kambara reactor slag powder as a sustainable stabilizer for clayey soils in road construction

• Published in: Innovative infrastructure solutions : the official journal of the Soil-Structure Interaction Group in Egypt (SSIGE) 2024-08, Vol.9 (8), Article 328
• Main Authors: Mendoza, Luis E. C., Gomes, Guilherme J. C., Pires, Patrício J. M., Bridi, Lucas O.
• Format: Article
• Language: English
• Subjects: Earth and Environmental Science; Earth Sciences; Environmental Science and Engineering; Foundations; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Technical Paper
• ISSN: 2364-4176; 2364-4184
• DOI: 10.1007/s41062-024-01581-8

Steel manufacturers around the world are looking for ways to produce higher quality, lower-sulfur steel. This requires an additional desulfurization step using the Kambara reactor (KR) during steel production. As a side effect, the Kambara reactor’s slag processing generates emissions that are captured and concentrated in dust collectors such as bag filters, reducing overall air pollution. While the use of KR slag has gained attention in the road material industry for improving pavement design performance, the reuse potential of KR slag powder (KRSP), collected by special bag filters, remains underexplored. This study investigates the chemical composition, physical properties, and mechanical characteristics of clayey soil mixed with KRSP. To assess the byproduct’s ability to stabilize this soil, laboratory experiments were conducted on raw materials and soil mixed with 3% and 5% KRSP. The results reveal that the specific gravity of KRSP (2.23 g/cm 3 ) is lower than that of granulated KR slag. X-ray fluorescence analysis detected no iron (Fe) in its composition, and the percentage of calcium oxide (CaO) was below 40%. Portland cement (Ca(OH) 2 ) was identified as the main mineral present through X-ray diffraction analysis, and brucite (Mg(OH) 2 ) as the minor mineral. The addition of 3% and 5% KRSP to clayey soil resulted in a significant increase in California Bearing Ratio (CBR) values (from 13 to 42% and 41%, respectively) after only 4 days of curing. Unconfined compressive strength values obtained for the 3% and 5% KRSP mixtures were 1.25 MPa and 0.95 MPa, respectively, after 7 days of curing. Atterberg limits, particle size distribution, and expansion tests reinforced the results, showing compliance with the requirements for first-class subbase materials. This finding demonstrates that KR desulfurization dust collector powder has the potential to be used as an environmentally friendly stabilizing agent, contributing to improved waste management in the steel industry.