Comparison of LC3 and traditional SCM-blended cement pastes under supercritical CO2 exposure

Comparison of LC3 and traditional SCM-blended cement pastes under supercritical CO2 exposure

Článek WoS

Carbonation of cementitious materials is a critical issue affecting the long-term performance of geothermal wells. This study compares the resistance of limestone calcined clay cements (LC3) and traditional SCM-based (silica fume and metakaolin) cement pastes exposed to supercritical CO2 for 7 days. The extent of carbonation and the associated phase transformations resulting from carbonation reactions were assessed using TGA, XRD, FTIR, and SEM-EDX analyses. Additionally, bulk density and compressive strength tests were conducted to evaluate the mechanical properties. The results demonstrated that the LC3 composition exhibited superior resistance to carbonation compared to the mixtures incorporating silica fume and metakaolin at an equivalent level of cement replacement. Higher carbonation penetration in traditional SCM-based systems is evidenced by up to 52 % higher carbonate contents in the middle part of the samples. This enhanced carbonation is attributed to the limited portlandite buffering capacity. In the middle part of the sample, LC3-70 contained up to 55 % more portlandite, indicating both reduced carbonation and lower pozzolanic reactivity of the calcined clay and limestone compared to SF/MK mixtures. Higher portlandite content in LC3 favoured more extensive carbonation-induced densification of the pore structure, effectively impeding CO2 ingress. In addition, this process contributed to an increase in compressive strength, which reached 53 MPa, approximately 34 % higher than that of the corresponding composition cured under standard water-hydration conditions. For highly carbonated SF/MK samples, compressive strength increased by 77 % reaching up to 93 MPa.

Carbonation of cementitious materials is a critical issue affecting the long-term performance of geothermal wells. This study compares the resistance of limestone calcined clay cements (LC3) and traditional SCM-based (silica fume and metakaolin) cement pastes exposed to supercritical CO2 for 7 days. The extent of carbonation and the associated phase transformations resulting from carbonation reactions were assessed using TGA, XRD, FTIR, and SEM-EDX analyses. Additionally, bulk density and compressive strength tests were conducted to evaluate the mechanical properties. The results demonstrated that the LC3 composition exhibited superior resistance to carbonation compared to the mixtures incorporating silica fume and metakaolin at an equivalent level of cement replacement. Higher carbonation penetration in traditional SCM-based systems is evidenced by up to 52 % higher carbonate contents in the middle part of the samples. This enhanced carbonation is attributed to the limited portlandite buffering capacity. In the middle part of the sample, LC3-70 contained up to 55 % more portlandite, indicating both reduced carbonation and lower pozzolanic reactivity of the calcined clay and limestone compared to SF/MK mixtures. Higher portlandite content in LC3 favoured more extensive carbonation-induced densification of the pore structure, effectively impeding CO2 ingress. In addition, this process contributed to an increase in compressive strength, which reached 53 MPa, approximately 34 % higher than that of the corresponding composition cured under standard water-hydration conditions. For highly carbonated SF/MK samples, compressive strength increased by 77 % reaching up to 93 MPa.

Limestone calcined clay cement pastes, Silica fume, Metakaolin, Supercritical CO2

Limestone calcined clay cement pastes, Silica fume, Metakaolin, Supercritical CO2

COMPEĹOVÁ K., MÁSILKO J.; ŠVOREC J.; PECIAR P.; KUZIELOVÁ E.

01.03.2026

The Journal of supercritical fluids

229

March 2026

Nizozemsko

106832

13

https://www-sciencedirect-com.ezproxy.lib.vutbr.cz/science/article/pii/S0896844625003195?via%3Dihub#sec0085