Carbonation Curing of Cement-Based Materials

Carbonation curing is an innovative process in which ambient or elevated carbon dioxide is introduced to freshly cast or precast cementitious materials to induce rapid formation of carbonate phases. During this process, CO₂ diffuses into capillary pores and reacts with calcium-bearing phases—most notably calcium silicate hydrate and portlandite—to form stable calcium carbonate. The exothermic mineralisation reaction accelerates strength development, refines pore structure and immobilises CO₂ within the matrix. Compared with conventional moisture curing, carbonation curing can achieve significant early‐age compressive strength gains and improved surface hardness, while also offering a route to net CO₂ sequestration if powered by low‐carbon energy. Practical implementations include accelerated carbonation of precast blocks, panels and recycled concrete fines, each tailored to optimise curing temperature, pressure, CO₂ concentration and exposure time. Challenges remain in ensuring uniform CO₂ penetration, managing reaction heat, controlling polymorphic carbonate assemblages and integrating the process into existing production lines. From a life‐cycle perspective, the balance of CO₂ captured versus emissions for gas capture, compression and energy input is critical. Globally, carbonation curing holds promise to decarbonise cement and concrete production by combining industrial CO₂ streams with widespread cement demand, but realising its full potential requires further refinements in process design, scale‐up strategies and durability assessments.

Research from Nature Portfolio

Recent studies have demonstrated that mineral carbonation of fines derived from recycled concrete can sequester the total CO₂ emitted during original clinker production. Under controlled conditions, lab and industrial‐scale experiments achieved full carbonation within hours, yielding gels with pronounced pozzolanic activity that enhance subsequent reactivity when reincorporated into new binders. These findings establish recycled fines as both a carbon sink and a supplementary cementitious material, offering more than 30 % additional CO₂ savings compared to simple limestone replacement. Another analysis has evaluated the net climate benefit of concrete produced with CO₂ curing and mixing. By accounting for CO₂ emissions from capture, transport and energy use, alongside variations in compressive strength, it was shown that a majority of existing datasets predict a net CO₂ increase. The work identifies two key levers to turn this balance positive: ensuring a demonstrable rise in strength from CO₂ treatments and reducing the electricity intensity of the curing process. These insights guide future optimisation of CO₂ curing systems toward genuine climate mitigation.

Carbonation Curing of Cement-Based Materials publication trend

The graph below shows the total number of articles in carbonation curing of cement-based materials across all publications each year (not limited to Nature Index journals).

Technical terms

Carbonation curing: The process of exposing fresh or precast cementitious materials to carbon dioxide to accelerate cementitious reactions and sequester CO₂ in the form of stable carbonates.

Calcium silicate hydrate (C-S-H): The principal binding phase formed during cement hydration, contributing to strength and durability.

Pozzolanic reaction: A secondary chemical reaction in which amorphous silica or alumina reacts with calcium hydroxide to form additional cementitious compounds.

Mineral carbonation: A chemical process that converts CO₂ into solid carbonate minerals by reaction with alkaline earth metals.

Carbonate polymorphs: Distinct crystalline forms of calcium carbonate, such as calcite, aragonite and vaterite, each with unique stability, morphology and mechanical influence.

References

1. Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete. Scientific Reports (2020).
2. Carbon dioxide utilization in concrete curing or mixing might not produce a net climate benefit. Nature Communications (2021).
3. Effect of temperature on CO2 curing, compressive strength and microstructure of cement paste. Cement and Concrete Research (2022).
4. Emerging CO2 utilization technologies for construction materials: A review. Journal of CO2 Utilization (2022).
5. CO2 storage in cement and concrete by mineral carbonation. Current Opinion in Green and Sustainable Chemistry (2022).
6. Calculation of greenhouse gas emissions for a carbon recycling system using mineral carbon capture and utilization technology in the cement industry. Journal of Cleaner Production (2021).