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


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

[1] IPCC, (2014). Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.

[2] International Energy Agency, (2018), Technology Roadmap: Low-Carbon Transition in the Cement Industry, 1–66. doi:10.1007/SpringerReference_7300.

[3] Walling, S.A. and Provis, J.L. (2016). Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future?. Chem. Rev., vol. 116, pp. 4170–4204.

[4] Sonat, C., Lim, C.H., Liska, M. and Unluer, C. (2017). Recycling and reuse of reactive MgO cements – A feasibility study. Constr. Build. Mater., vol. 157, pp. 172–181.

[5] Shand, M.A. (2006). The Chemistry and Technology of Magnesia. (Hoboken: John Wiley & Sons).

[6] Li, Z. and Chau, C.K. (2007). Influence of molar ratios on properties of magnesium oxychloride cement. Cem. Concr. Res., vol. 37, pp. 866–870.

[7] Humbert, P.S. and Castro-Gomes, J. (2018). CO2 activated steel slag-based materials: A review. J. Clean. Prod., vol. 208, pp.448–457.

[8] Liu, L.,et al. (2001). Development of a CO2solidification method for recycling autoclaved lightweight concrete waste. J. Mater. Sci. Lett., vol. 20, pp. 1791–1794.

[9] Mo, L., et al. (2016). Effectiveness of using CO 2 pressure to enhance the carbonation of Portland cement-fly ash-MgO mortars. Cem. Concr. Compos., vol. 70. pp. 78–85.

[10] Bernal, S.A. et al. (2014). Natural carbonation of aged alkali-activated slag concretes. Mater. Struct., vol. 47, pp. 693–707.

[11] Bukowski, J.M. and Berger, R.L. (1979). Reactivity and strength development of CO2 activated non- hydraulic calcium silicates. Cem. Concr. Res., vol. 957–68.

[12] Castro-Gomes, J. (2017). Materiais Reciclados por Ativação Alcalina. Rev. Mater. Construção Da Assoc. Port. Das Empres. Mater. Construção. pp. 36–40.

[13] Sedira, N. and Castro-Gomes J., (2020). Effect of activators on hybrid alkaline binder based on tungsten mining waste and ground granulated blast furnace slag. Constr. Build. Mater., vol. 232.

[14] Beghoura, I. and Castro-Gomes, J. (2019). Design of alkali-activated aluminium powder foamed materials for precursors with different particle sizes. Constr. Build. Mater., vol. 224, pp. 682–690.

[15] British Standard, (1992). BS EN 196-6:1992. Methods of testing cement. Determination of fineness. British Standards Institution. London UK.

[16] British Standard, (1990). BS 1377-2: 1990. Methods of test for soils for civil engineering purposes. Classification tests. British Standards Institution. London UK.