Investigation of carbonation depth and its influence on the performance and microstructure of MgO cement and PC mixes

• Carbonation potential of MgO and PC concrete mixes were studied at different depths.
• Mix performances were assessed by their strength, density, porosity and CO2 uptake.
• MgO mixes achieved higher carbonation degrees and strengths than PC mixes.
• Dense networks of various carbonates were observed at different sample depths.
• Providing a continuous path for CO2 diffusion through careful mix design is vital.

This paper investigates the carbonation potential, strength gain and microstructural development of magnesium oxide (MgO) blocks and provides a comparison with Portland cement (PC) blocks. Performance was evaluated in terms of density, porosity, compressive strength and microstructure at different depths along sample cross-sections. Scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), pH measurement and acid digestion analyses provided information on the amount of CO2 absorbed, mix morphology and carbonation progress at different depths. The relationship between performance and CO2 uptake; and the influence of key parameters on the carbonation, microstructure and mechanical performance of MgO-based samples was established.