Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud

Abstract

In this preliminary study, the effect of the pre-drying stage, water immersion, carbonation curing cycles, and/or drying stage on carbonation curing of magnesium oxide-rich powder (MRP) was investigated. In addition, a blend of tungsten mining waste mud (TMWM) with MRP was also evaluated. The MRP and TMWM used have maximum grain sizes of 125 μm. The cement pastes were produced with 0 and 50 of TMWM weight percentage. The specimens were compacted into cylindric moulds (∅ = 20 mm; h = 40 mm) under 30 MPa and, subsequently, submitted to five different processes of curing involving a pre-drying stage before carbonation, rapid water immersion cycles, additional drying periods, and different carbonation curing periods. The atmosphere of the pressurized carbonation curing chamber was controlled to provide a CO2 concentration of > 99%, the partial pressure of 1 bar and temperature of 60°C. The influence of the curing processes on the compressive strength of each mix was determined 12 hours after the carbonation curing period. This study demonstrates that the water content during the curing process plays an important role in the increase of the hardening process and on the compressive strength.
 Keywords: Carbonation curing, magnesium oxide, mining waste, curing processes, magnesium-based cement