Accelerated carbonation of hardened cement pastes: Influence of porosity

Wang, Jinbang; Xu, Hongxin; Xu, Da; Du, Peng; Zhou, Zhen; Yuan, Liang; Cheng, Xin

doi:10.1016/j.conbuildmat.2019.07.088

Cited by 132 publications

(40 citation statements)

References 31 publications

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“…Based on the data provided and analysis conducted in this study, it can be concluded that MOC cement represents an alternative construction binder for the production of low carbon materials that can partially mitigate the atmospheric concentration of CO 2 , which is the main constituent of greenhouse gases related to global warming issues [51].…”

Section: Resultsmentioning

confidence: 87%

Carbon Dioxide Uptake by MOC-Based Materials

et al. 2020

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In this work, carbon dioxide uptake by magnesium oxychloride cement (MOC) based materials is described. Both thermodynamically stable magnesium oxychloride phases with stoichiometry 3Mg(OH)2∙MgCl2∙8H2O (Phase 3) and 5Mg(OH)2∙MgCl2∙8H2O (Phase 5) were prepared. X-ray diffraction (XRD) measurements were performed to confirm the purity of the studied phases after 7, 50, 100, 150, 200, and 250 days. Due to carbonation, chlorartinite was formed on the surface of the examined samples. The Rietveld analysis was performed to calculate the phase composition and evaluate the kinetics of carbonation. The SEM micrographs of the sample surfaces were compared with those of the bulk to prove XRD results. Both MOC phases exhibited fast mineral carbonation and high maximum theoretical values of CO2 uptake capacity. The materials based on MOC cement can thus find use in applications where a higher concentration of CO2 in the environment is expected (e.g., in flooring systems and wall panels), where they can partially mitigate the harmful effects of CO2 on indoor air quality and contribute to the sustainability of the construction industry by means of reducing the carbon footprints of alternative building materials and reducing CO2 concentrations in the environment overall.

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Section: Resultsmentioning

confidence: 87%

Carbon Dioxide Uptake by MOC-Based Materials

et al. 2020

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“…Considering the effect of different CO 2 concentrations on microstructures, the microstructure was dense but still relatively loose under natural carbonation, while it was more compact and denser under accelerated carbonation, causing a potential decrease in the transport speed of CO 2 [ 12 , 37 ]. No big differences were found for the samples carbonated from 3% to 100% CO 2 , thus, it seems that the carbonated microstructure under accelerated conditions is less affected by CO 2 concentration.…”

Section: Resultsmentioning

confidence: 99%

Slag Blended Cement Paste Carbonation under Different CO2 Concentrations: Controls on Mineralogy and Morphology of Products

Liu

Lin

et al. 2020

Materials

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To investigate the effect of different CO2 concentrations on the carbonation results of slag blended cement pastes, carbonation experiments under natural (0.03% CO2) and accelerated conditions (3, 20, and 100% CO2) were investigated with various microscopic testing methods, including X-ray diffraction (XRD), 29Si magic angle spinning nuclear magnetic resonance (29Si MAS NMR) and scanning electron microscopy (SEM). The XRD results indicated that the major polymorphs of CaCO3 after carbonation were calcite and vaterite. The values of the calcite/(aragonite + vaterite) (c/(a + v)) ratios were almost the same in all carbonation conditions. Additionally, NMR results showed that the decalcification degree of C-S-H gel exposed to 0.03% CO2 was less than that exposed to accelerated carbonation; under accelerated conditions, it increased from 83.1 to 84.2% when the CO2 concentration improved from 3% to 100%. In SEM observations, the microstructures after accelerated carbonation were denser than those under natural carbonation but showed minor differences between different CO2 concentrations. In conclusion, for cement pastes blended with 20% slag, a higher CO2 concentration (above 3%) led to products different from those produced under natural carbonation. A further increase in CO2 concentration showed limited variation in generated carbonation products.

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“…The porosity in this range also decreased when the CO 2 concentration was increased to 100% (CO 2 uptake of 17.3 g/kg). This decrease was undoubtedly due to the clogging of pores by the formation of calcium carbonates during carbonation, which has been observed in both cement pastes [40,53,54] and RCAs [55]. The calcium carbonates that are formed accumulate and fill large pores.…”

Section: Changes In the Pore Size Distribution Of An Rca By Mercury Intrusion Porosimetrymentioning

confidence: 96%

“…However, there is no information about the impact of natural carbonation on the decrease of the WAC and the influence of accelerated carbonation. The total porosity, obtained by mercury intrusion porosimetry (MIP), is also affected by carbonation due to the total disappearance of pores of more than 300 nm and the increased presence of pores less than 30 nm only in concretes or in cement pastes [37,40].…”

Section: Introductionmentioning

confidence: 99%

Improvement of Recycled Aggregates Properties by Means of CO2 Uptake

et al. 2021

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Concrete from deconstruction can have a second life in the form of recycled concrete aggregates (RCAs). They unfortunately have poor properties (high porosity and water absorption coefficient (WAC)) with respect to natural aggregates. Accelerated carbonation was implemented to improve the RCA properties and to increase their use by storing carbon dioxide (CO2) in the cement matrix and thereby reduce their environmental impact. This paper aims to perform a parametric study of a process for accelerated carbonation of RCAs to store the largest possible amount of CO2 and improve their properties. This study highlights the fact that each of these parameters affects CO2 storage, with an optimum water content for the maximum CO2 uptake depending on the nature and the source of the RCAs. This optimum is related to the RCA water absorption coefficient by a linear relationship. The results show that accelerated carbonation reduces the water absorption coefficient by as much as 67%. Finally, carbonation also decreases porosity, as observed by mercury intrusion porosimetry, by filling the capillary pores.

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Accelerated carbonation of hardened cement pastes: Influence of porosity

Cited by 132 publications

References 31 publications

Carbon Dioxide Uptake by MOC-Based Materials

Carbon Dioxide Uptake by MOC-Based Materials

Slag Blended Cement Paste Carbonation under Different CO2 Concentrations: Controls on Mineralogy and Morphology of Products

Improvement of Recycled Aggregates Properties by Means of CO2 Uptake

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