Potential investigation of concrete fines as an alternative material: A novel neutralizer for acid mine drainage treatment

The concomitant generation of concrete fines as a byproduct during aggregate recycling is problematic in entire concrete recycling system. The properties of concrete fines mostly composed of hydrated cement limits the availability in construction use. Effective utilization of concrete fines must be explored to improve the negative environmental impact from the cement and concrete industries. Developing concrete fines as alternative material is one of promising options. This study investigated the potential of concrete fines as novel neutralizer for acid mine drainage (AMD) to explore the effective use of concrete fines. The neutralization performance, including identification of main substance that provide alkalinity, removal mechanism of As, Fe, and comparison with conventional neutralizers were confirmed by discussing the effect of dosage and particle size on AMD neutralization. The sedimentation performance was determined, and the neutralized sludge that was derived from concrete fines showed good settling properties: compactness, and dewatering ability. Moreover, CO2 emissions in AMD neutralization were considered, and CO2 emission reduction by Ca(OH)2 and CaCO 3 substitution by concrete fines was assessed. This first fundamental investigation of concrete fines utilization in AMD treatment determined the potential for neutralization and established the prime consideration of CO2 emissions.