Researchers have developed a novel five-dimensional imaging system to observe real-time moisture movement, chemical transformation, and mechanical damage during concrete carbonation, paving the way for enhanced sustainable construction practices.
Researchers have deployed a novel operando five-dimensional imaging system to observe, in real time, the interplay of moisture movement, chemical transformation and mechanical damage as cement paste carbonates , a development that could sharpen strategies for using recycled concrete as a CO2 sink while protecting material performance.
According to a paper in Communications Materials by El Faqir, Tengattini, Huet, Briffaut and Dal Pont, the team combined simultaneous neutron and X‑ray tomography with time-resolved acquisition to follow three‑dimensional microstructure, complementary contrast mechanisms and temporal evolution during accelerated carbonation. Experiments were run under conditions chosen to mirror industrial accelerated‑carbonation treatments , elevated temperature and very low relative humidity , and used a bespoke confinement chamber and the NeXT dual‑modality instrument to collect neutron (high sensitivity to hydrogen and thus water) and X‑ray (high spatial resolution of mineral phases and cracking) tomographies at sub‑millimetre resolution every 25 minutes.
The imaging revealed a tightly coupled thermo‑hydro‑chemo‑mechanical sequence. Neutron measurements tracked the release and redistribution of bound and free water as hydrate phases decomposed, while X‑ray volumes mapped crack initiation, propagation and partial closure associated with calcium carbonate precipitation. The authors observed that carbonation does not proceed as a single uniform diffusion front: early stage transport is diffusion dominated but later slows as moisture accumulates and carbonate precipitation reduces effective porosity, producing a bilinear front whose behaviour cannot be predicted by simple diffusive models alone. Cracking was found to correlate with local drying shrinkage and low‑moisture zones rather than being a direct, isolated effect of CO2 exposure.
Those mechanistic insights are directly relevant to the growing interest in using construction and demolition waste as aggregate to close material loops and capture carbon. Industry data indicate billions of tonnes of concrete waste are generated each year and that recycled aggregate streams offer very large theoretical capacity for carbonation‑based sequestration if their microstructure and durability implications are properly managed. The new operando method gives engineers the kind of spatially and temporally resolved evidence needed to optimise accelerated carbonation treatments so they enhance pore filling and mechanical stability without inducing detrimental cracking.
The study’s findings sit alongside, and help reconcile, a range of other non‑destructive and analytical approaches. Raman microscopy work has already shown rapid surface formation of calcite under aggressive CO2 exposure and slower phase evolution under natural carbonation, clarifying which carbonate polymorphs form and how quickly portlandite and ettringite deplete at exposed surfaces. Nuclear magnetic resonance techniques have been demonstrated as a field‑capable way to detect shifts in pore structure and moisture profiles associated with carbonation fronts, offering portable complements to laboratory tomographies. Separate ultrasonic analyses have produced promising signal‑based indices that correlate with carbonation progression over months, while scanning electron microscopy, when combined with advanced sample preparation, can resolve phase and pore size changes down to the nanometre scale. Together these methods provide overlapping windows on hydration chemistry, pore evolution and damage processes; the operando 5D approach integrates several of those windows simultaneously, reducing uncertainty about cause and effect.
Modelling efforts also benefit from the richer datasets. A recent finite‑element framework that couples water transport in cracked concrete with carbonation and corrosion currents demonstrates that predictions of carbonation penetration and corrosion risk are sensitive to saturation dynamics and wetting–drying cycles. High‑fidelity, time‑resolved imaging of water release, pore occlusion by carbonates and crack evolution offers empirical constraints that can improve such models’ predictive power for service life and for optimising industrial carbonation schedules.
For practitioners focused on industrial decarbonisation, the practical implications are threefold. First, accelerated carbonation protocols can be tuned to favour pore filling and densification while minimising drying‑shrinkage cracking, increasing the usability of recycled aggregate. Second, monitoring strategies that combine moisture‑sensitive and mineral‑sensitive techniques , or that mirror the dual‑modality approach in situ , will better detect early signs of deleterious damage. Third, coupling operando observations with validated models enables more reliable forecasts of CO2 uptake, structural performance and long‑term durability under realistic cycling and environmental exposure.
The authors stress that the operando 5D technique captures transient phenomena that single‑modality or ex situ analyses can miss, such as the distinction between bound and free water during ongoing reactions and the transient clogging of transport pathways by carbonate precipitation. According to the paper, these capabilities make it possible to refine both materials design and process parameters for carbonation treatments, advancing the twin goals of effective carbon sequestration and structural resilience in circular concrete systems.
As the construction sector seeks scalable routes to reduce embodied emissions, methodologies that reveal the coupled physics and chemistry of carbonation under practical conditions will be essential. The operando 5D tomography approach provides a new empirical foundation for those efforts, while complementary tools and improved multi‑physics models offer routes to convert the mechanistic knowledge into deployable industrial practice.
- https://www.azobuild.com/news.aspx?newsID=23973 – Please view link – unable to able to access data
- https://www.mdpi.com/2071-1050/14/14/8572 – This study investigates the carbonation mechanism in cracked hardened cement paste (HCP) by examining changes in pore structure and cement hydration phases. The findings reveal that carbonation leads to a decrease in total pore volume due to precipitation and densification of HCP, formation of new mesopores and capillary pores, and microcracking resulting from the carbonation of calcium hydroxide (CH) and calcium silicate hydrate (C-S-H) phases. Additionally, a decrease in gel pores (<4.5 nm) was observed after carbonation, likely related to C-S-H carbonation leading to calcium carbonate precipitation, while further C-S-H decalcification increases the mesopore fraction. The study provides insights into the complex interactions between carbonation and cracking in HCP, which are crucial for understanding the durability of concrete structures.
- https://pubmed.ncbi.nlm.nih.gov/35076109/ – This study explores the feasibility of using Raman microscopy for real-time monitoring of early surface carbonation in hardened cement pastes over a period of up to seven days. Samples were exposed to both natural carbonation (440 ppm CO₂) and accelerated carbonation (4% CO₂), with the evolution of calcium carbonate polymorphs, portlandite, ettringite, C-S-H gel, and unreacted cement particles being tracked. The results indicate that calcite is the primary polymorph formed under both natural and accelerated carbonation conditions. Under accelerated carbonation, calcite formation on the sample surface completed within one day, whereas under natural carbonation, the formation of calcite is expected to continue beyond seven days. The study also observes that the contents of portlandite and ettringite decreased rapidly under accelerated carbonation but much more gradually under natural carbonation, while calcium silicate minerals in unreacted cement particles remained unchanged throughout the carbonation processes.
- https://link.springer.com/article/10.1617/s11527-017-1019-5 – This research employs unilateral magnetic resonance to obtain CPMG T₂ decay measurements at different positions along six-centimetre-long cement paste samples to detect the carbonation front based on changes in pore structure caused by accelerated carbonation. Cement pastes with water-to-cement ratios of 0.60, 0.50, and 0.40 were prepared using ordinary Portland cement. After moist curing and conditioning at 65% relative humidity and 35°C, the pastes were subjected to accelerated carbonation with 4% by volume CO₂ at 65% relative humidity and 35°C. The study demonstrates that nuclear magnetic resonance (NMR) is a non-destructive technique capable of studying moisture movement in cement-based materials during drying and water absorption, as well as observing chloride and sodium ion penetration. NMR has also been used to observe changes in the pore space of hydrated cement pastes. The development of portable and embedded NMR devices allows measurements of samples in the laboratory or in field structures.
- https://arxiv.org/abs/2501.11147 – This paper presents a set of non-destructive ultrasound-based indexes, obtained solely from non-linear and linear analyses of ultrasonic signals, for measuring the carbonation of Portland cement pastes. Class 30RS cement pastes with three water/cement ratios by weight (0.4, 0.5, and 0.6) were considered. Carbonation was carried out for 120 days with a constant CO₂ level of 4% by volume under controlled temperature and humidity, considering unidirectional carbonation, parallel to the longitudinal axis of the samples. The level of carbonation was validated by FTIR measurements. From these analyses, different indexes with high correlation were obtained, estimated only from the ultrasonic signals and as a function of the days of exposure to carbonation, as well as of the percentage of carbonation. Further study is required for the evaluation of the reliability of these promising indexes for the determination of carbonation in cement-based materials.
- https://arxiv.org/abs/2405.02611 – This paper presents a modelling framework for predicting carbonation-induced corrosion in reinforced concrete. The framework includes a new model for water transport in cracked concrete, a link between corrosion current density and water saturation, and a theory for characterising concrete carbonation. The theoretical framework is numerically implemented using the finite element method, and model predictions are extensively benchmarked against experimental data. The results show that the model is capable of accurately predicting carbonation progress, as well as wetting and drying of cracked and uncracked concrete, revealing a very good agreement with independent experiments from a set of consistent parameters. In addition, insight is gained into the evolution of carbonation penetration and corrosion current density under periodic wetting and drying conditions. Among others, it is found that cyclic wetting periods significantly speed up the carbonation progress and that the induced corrosion current density is very sensitive to concrete saturation.
- https://arxiv.org/abs/2108.08137 – Scanning electron microscopy (SEM) imaging is able to visualize micro- to nano-structures of cement and concrete. A prerequisite is that the sample preparation preserves the native structure of the specimen. In this study, argon Broad Ion Beam (BIB) sectioning is compared to state-of-the-art sample preparation (resin embedding, polishing) for hydrated alite. Additionally, it is investigated if during BIB, sample cooling is beneficial to avoid deterioration of cement hydrates. The aim is to quantitatively measure phase and pore size distributions in hardened alite pastes. Therefore, not only optimized sample preparation but also optimized imaging conditions are investigated. Finally, it is demonstrated that by image analysis, pores down to a diameter of 5 nm in hydrated alite pastes can be quantitatively analysed.
Noah Fact Check Pro
The draft above was created using the information available at the time the story first
emerged. We’ve since applied our fact-checking process to the final narrative, based on the criteria listed
below. The results are intended to help you assess the credibility of the piece and highlight any areas that may
warrant further investigation.
Freshness check
Score:
8
Notes:
The article was published on January 20, 2026, which is recent. However, the study it discusses was published in Communications Materials in 2026, indicating that the content is based on a press release summarising the study. This typically warrants a high freshness score, but the reliance on a press release may affect the originality of the content.
Quotes check
Score:
7
Notes:
The article includes direct quotes from the study authors. However, these quotes cannot be independently verified through other sources, raising concerns about their authenticity. The lack of independent verification reduces the reliability of the quotes.
Source reliability
Score:
6
Notes:
The article originates from AZoBuild, a niche publication focusing on construction and building materials. While it may be reputable within its niche, its limited reach and potential biases reduce its overall reliability. Additionally, the article appears to be summarising a press release, which may affect its independence.
Plausability check
Score:
8
Notes:
The claims about the operando 5D imaging technique and its applications in understanding carbonation in cement paste are plausible and align with current scientific understanding. However, the lack of independent verification of the study’s findings raises concerns about their accuracy.
Overall assessment
Verdict (FAIL, OPEN, PASS): FAIL
Confidence (LOW, MEDIUM, HIGH): MEDIUM
Summary:
The article presents a recent study on a novel 5D imaging technique for observing carbonation in cement paste. However, it relies on a press release summarising the study, and the quotes included cannot be independently verified. The source, AZoBuild, is a niche publication with limited reach, and the lack of independent verification of the study’s findings raises concerns about the content’s reliability. Therefore, the overall assessment is a FAIL with MEDIUM confidence.
