Effect of supplementary cementitious materials on carbonation of cement pastes

Saillio, Mickaël; Baroghel-Bouny, Véronique; Pradelle, Sylvain; Bertin, Matthieu; Vincent, Julien; Lacaillerie, Jean-Baptiste d’Espinose de

doi:10.1016/j.cemconres.2021.106358

Cited by 117 publications

(37 citation statements)

References 52 publications

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“…In agreement with the Rietveld content where~0.6 wt% of Portlandite was measured, no weight loss associated to this phase is observed in the thermal traces. Above 500 • C two endotherms are observed close to 570 and 770 • C. In the derivative of the weight loss, three peaks of different widths are measured at 570, 670 and 770 • C. These three peaks (three CaCO 3 decomposition modes) have been widely reported in the cement carbonation bibliography [12,14,58,60,61]. The broad endotherm centred at 570 • C, mode-III, is generally associated to the mass loss from calcium carbonate from the C-S-H gel [12,14,58], which is measured here as 16.1%.…”

Section: Thermal Analysismentioning

confidence: 77%

“…II. Carbonation of C-S-H gel, see reaction (2), proceeds by the removal of calcium ions yielding, initially through a de-calcified gel plus partial carbonation, and finally the formation of amorphous (calcium-containing) silica gel and several forms of CaCO 3 [9][10][11][12][13][14]. The extent of the C-S-H carbonation and the type of product formed depend upon the initial binder (Ca/Si ratio of the gel, water content, overall phase assemblage, etc.)…”

Section: Introductionmentioning

confidence: 99%

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X-ray Total Scattering Study of Phases Formed from Cement Phases Carbonation

2021

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Carbonation in cement binders has to be thoroughly understood because it affects phase assemblage, binder microstructure and durability performance of concretes. This is still not the case as the reaction products can be crystalline, nanocrystalline and amorphous. The characterisation of the last two types of components are quite challenging. Here, carbonation reactions have been studied in alite-, belite- and ye’elimite-containing pastes, in controlled conditions (3% CO2 and RH = 65%). Pair distribution function (PDF) jointly with Rietveld and thermal analyses have been applied to prove that ettringite decomposed to yield crystalline aragonite, bassanite and nano-gibbsite without any formation of amorphous calcium carbonate. The particle size of gibbsite under these conditions was found to be larger (~5 nm) than that coming from the direct hydration of ye’elimite with anhydrite (~3 nm). Moreover, the carbonation of mixtures of C-S-H gel and portlandite, from alite and belite hydration, led to the formation of the three crystalline CaCO3 polymorphs (calcite, aragonite and vaterite), amorphous silica gel and amorphous calcium carbonate. In addition to their PDF profiles, the thermal analyses traces are thoroughly analysed and discussed.

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Section: Thermal Analysismentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

X-ray Total Scattering Study of Phases Formed from Cement Phases Carbonation

2021

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“…The simultaneous presence of the

polymorphs in OPC pastes subjected to accelerated carbonation is still debated, and different hypotheses are advanced. The most frequent explanation involves the calcium-bearing precursor: The well-crystallized

from Mode I is attributed to the carbonation of portlandite, while the

from Modes II and III is associated with the carbonation of C-S-H and hydrated calcium aluminate phases [ 37 , 44 ]. The C/S ratio of C-S-H has also been associated with different

polymorphs [ 22 , 45 ].…”

Section: Resultsmentioning

confidence: 99%

Valorisation of Recycled Cement Paste: Feasibility of a Short-Duration Carbonation Process

et al. 2022

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Cement paste powder (CPP) is a by-product of the recycling process of concrete with an elevated carbonation capability and potential to be recycled as a binding material in new concrete batches. The application of a carbonation treatment to CPP improves this potential even more, besides the evident gains in terms of CO2 net balance. However, the long duration usually adopted in this treatment, from 3 to 28 days, hampers the industrial viability of the process. We studied the feasibility of a short-duration carbonation process, with a duration of two hours, carrying out a comprehensive characterization of the material throughout the process. The test was performed on CPP with an average initial water content of 16.9%, exposed to a CO2 concentration of 80%. The results demonstrate two main carbonation rates: a rapid growth rate in the first 18 minutes of the process, involving all the calcium-bearing compounds in CPP, and a slow growth rate afterwards, where only C-S-H contributes to the carbonation reaction. During the 2 h carbonation process, the main CPP compounds, calcium silicate hydrate (C-S-H) and calcium hydroxide (CH), reached different carbonation degrees, 31% and 94%, with, however, close CO2 uptake values, 8% and 11%, respectively. Nevertheless, the total CO2 uptake for this process (≈19%) attained values not distant from the values usually obtained in a carbonation of 12 days or more (19–25%). Hence, these findings highlight the blocking role of C-S-H in the carbonation process, indicating that longer carbonation periods are only going to be useful if an effective carbonation of this compound is accomplished. In the present scenario, where CH is the main contributor to the reaction, the reduction in the process duration is feasible.

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“…In mortar or concrete made with SCMs, which are pozzolanic or latent-hydraulic, the reaction processes are often delayed. Assuming CO 2 preferably interacts with calcium ions originating from hydrate phases [ 1 , 4 , 20 ], curing and pre-conditioning times and boundary conditions can have a significant impact on the test results [ 1 , 5 , 20 ]. Moreover, the total amount of CO 2 that can be bound (binding or buffering capacity of a binder) depends directly on the amount of (reacted) CaO available [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the total amount of CO 2 that can be bound (binding or buffering capacity of a binder) depends directly on the amount of (reacted) CaO available [ 2 ]. Thus, the CO 2 binding capacity of blended cements is generally lower than that of plain PC since the available CaO content is lower [ 4 , 20 ]. Also the main reaction product during hydration of blended cements is an (Al-substituted) C–S–H type phase with lower Ca/Si ratio than in plain PC systems at the expense of portlandite [ 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Report of RILEM TC 281-CCC: outcomes of a round robin on the resistance to accelerated carbonation of Portland, Portland-fly ash and blast-furnace blended cements

et al. 2022

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Many (inter)national standards exist to evaluate the resistance of mortar and concrete to carbonation. When a carbonation coefficient is used for performance comparison of mixtures or service life prediction, the applied boundary conditions during curing, preconditioning and carbonation play a crucial role, specifically when using latent hydraulic or pozzolanic supplementary cementitious materials (SCMs). An extensive interlaboratory test (ILT) with twenty two participating laboratories was set up in the framework of RILEM TC 281-CCC ‘Carbonation of Concrete with SCMs’. The carbonation depths and coefficients determined by following several (inter)national standards for three cement types (CEM I, CEM II/B-V, CEM III/B) both on mortar and concrete scale were statistically compared. The outcomes of this study showed that the carbonation rate based on the carbonation depths after 91 days exposure, compared to 56 days or less exposure duration, best approximates the slope of the linear regression and those 91 days carbonation depths can therefore be considered as a good estimate of the potential resistance to carbonation. All standards evaluated in this study ranked the three cement types in the same order of carbonation resistance. Unfortunately, large variations within and between laboratories complicate to draw clear conclusions regarding the effect of sample pre-conditioning and carbonation exposure conditions on the carbonation performance of the specimens tested. Nevertheless, it was identified that fresh and hardened state properties alone cannot be used to infer carbonation resistance of the mortars or concretes tested. It was also found that sealed curing results in larger carbonation depths compared to water curing. However, when water curing was reduced from 28 to 3 or 7 days, higher carbonation depths compared to sealed curing were observed. This increase is more pronounced for CEM I compared to CEM III mixes. The variation between laboratories is larger than the potential effect of raising the CO 2 concentration from 1 to 4%. Finally, concrete, for which the aggregate-to-cement factor was increased by 1.79 in comparison with mortar, had a carbonation coefficient 1.18 times the one of mortar. Supplementary Information The online version contains supplementary material available at 10.1617/s11527-022-01927-7.

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Effect of supplementary cementitious materials on carbonation of cement pastes

Cited by 117 publications

References 52 publications

X-ray Total Scattering Study of Phases Formed from Cement Phases Carbonation

X-ray Total Scattering Study of Phases Formed from Cement Phases Carbonation

Valorisation of Recycled Cement Paste: Feasibility of a Short-Duration Carbonation Process

Report of RILEM TC 281-CCC: outcomes of a round robin on the resistance to accelerated carbonation of Portland, Portland-fly ash and blast-furnace blended cements

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