Influence of CO2 concentration on the performance of MgO cement mixes

• Published in: Cement & concrete composites Vol. 115; p. 103826
• Main Authors: Dung, N.T., Hay, R., Lesimple, A., Celik, K., Unluer, C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2021
• Subjects: Carbonation; CO2 concentration; MgO cement; Microstructure; Strength; CO2 concentration; Carbonation; Microstructure; MgO cement; Strength
• ISSN: 0958-9465; 1873-393X
• DOI: 10.1016/j.cemconcomp.2020.103826

This paper investigated the influence of different CO2 concentrations on the microstructural and mechanical development of reactive MgO cement (RMC) concrete. Combination of various analyses revealed the enhancement of hydrated magnesium carbonate (HMC) phases with relatively superior micro-mechanical properties as the CO2 concentration increased from ambient (~0.04%) to accelerated (5–20%) levels. The higher CO2 diffusion within samples cured under 5–20% CO2 increased the compressive strength by ~5 times. While samples cured under 20% CO2 revealed high early strengths, the formation of a dense HMC layer on the sample exterior led to limitations on further CO2 diffusion. Use of 5% CO2 produced comparable strengths as 20% CO2 at 28 days, highlighting the potential of using lower concentrations. Samples cured under 10% CO2 revealed the best performance at 28 days, thereby defining this environment as the most favorable condition for the development of microstructural and mechanical properties of RMC concrete. •Reactive MgO cement (RMC) concrete was cured under ambient (0.04%) and 5–20% CO2 concentrations.•Increased CO2 diffusion under high CO2 levels enhanced carbonate properties and strength.•Formation of a dense HMC layer on sample exterior limited further CO2 diffusion.•Use of 5% CO2 produced similar 28-day strengths as 20% CO2, eliminating the need for high CO2.•10% CO2 provided the best condition for microstructural and mechanical development at 28 days.