CO₂ Concrete Curing
TTS v1.0 - Annex J
CO₂ Concrete Curing injects captured CO₂ directly into fresh concrete during the curing process, where it reacts with calcium silicate hydrate to form stable calcium carbonate minerals within the hardened concrete matrix. The reaction both permanently sequesters the injected CO₂ and improves the concrete's compressive strength - a rare pathway where the climate benefit and the product's core performance property improve together, at the point of manufacture for one of the world's most widely used construction materials.
Submit Concrete Curing Project View TTS v1.0 Annex J →How this pathway works
Fresh concrete - a mixture of cement, water, and aggregate - is naturally alkaline, and calcium silicate hydrate (the primary binding phase formed as cement hydrates) reacts readily with CO₂ to form calcium carbonate. CO₂ Concrete Curing exploits this chemistry deliberately: captured CO₂ gas is injected into concrete during mixing, at a dedicated curing chamber for precast products, or into fresh cement paste before or during the hydration reaction, accelerating and directing carbonate mineral formation throughout the concrete matrix rather than relying on the slow, superficial carbonation that occurs naturally as hardened concrete is exposed to atmospheric CO₂ over decades.
Under the Teravent Technology-Based Carbon Standard (TTS v1.0) Annex J, CO₂ Concrete Curing projects earn Teravent Technology Credits for verified net tonnes of CO₂ permanently mineralised within the cured concrete product, net of full lifecycle project emissions. This pathway carries a mixed credit type designation (TTC-D / R) - the specific type depends on the origin of the CO₂ injected. Where the CO₂ source is captured atmospheric or biogenic carbon, the project earns Removal credits (TTC-R); where the source is industrial flue gas, it earns Reduction credits (TTC-D), following the same source-based logic applied throughout TTS v1.0.
Three methodology variants are approved under Annex J, differentiated by the concrete production format - precast products, ready-mix cast-in-place concrete, and cement replacement material treatment. Each specifies its own injection point, curing process, and mineralisation confirmation protocol.
TTS v1.0 - Annex J
This pathway is governed exclusively by the Teravent Technology-Based Carbon Standard (TTS v1.0). No external registry, standard, or methodology is referenced or incorporated. All requirements - additionality, quantification, durability, safeguards, and credit issuance - are defined within TTS v1.0 and Annex J specifically.
Three approved methodology variants
TTS v1.0 Annex J approves three discrete methodology types for the CO₂ Concrete Curing pathway, differentiated by the point in concrete production where CO₂ is injected and the resulting curing process.
Precast concrete products - masonry blocks, pavers, structural panels - are cured in dedicated chambers where CO₂ concentration, humidity, and temperature can be tightly controlled, making this the most mature and widely deployed methodology in the pathway. CO₂ is introduced during the early curing window when calcium silicate hydrate formation is most reactive, maximising both carbonate uptake and the resulting compressive strength gain.
- CO₂ gas uptake within curing chamber via calibrated gas analysis, ±2% accuracy
- Carbonate mineral content of cured product confirmed by thermogravimetric analysis (TGA) at representative sampling frequency
- Compressive strength testing per batch, confirming the co-benefit performance improvement alongside carbon uptake
- CO₂ source documentation and chain-of-custody, determining TTC-D versus TTC-R credit type classification
- Product distribution and end-use tracking to prevent double counting of embodied-carbon claims by downstream purchasers
Ready-mix concrete destined for cast-in-place applications - foundations, slabs, walls poured on-site - receives a metered CO₂ dose during batching at the concrete plant, before the mix is transported to the pour site. Because curing occurs after transport and pour rather than in a controlled chamber, this methodology requires more conservative uptake assumptions and additional field verification relative to precast curing, but addresses a substantially larger share of total global concrete production.
- CO₂ dosing rate at the batching plant via calibrated metering, ±2% accuracy
- Core sampling from a representative subset of poured structures to confirm carbonate mineral content via TGA
- Compressive strength testing per batch and, where feasible, on cured field samples
- CO₂ source documentation and chain-of-custody, determining TTC-D versus TTC-R credit type classification
- Pour site and structure-level record keeping to support the product's end-use tracking obligation
Rather than treating the finished concrete, this methodology applies CO₂ curing to supplementary cementitious materials (SCMs) - fly ash, ground granulated blast furnace slag, or other alkaline industrial byproducts - before they are blended into the cement mix, reducing the overall clinker content required (a further embodied-carbon benefit) while achieving carbonate mineralisation in the SCM component itself. Where the SCM feedstock is also registered under Industrial Waste Mineralisation (Annex F), projects must confirm no double registration of the same mineralised tonnes.
- CO₂ gas uptake at the SCM treatment reactor or curing process, via calibrated gas analysis, ±2% accuracy
- Carbonate mineral content of treated SCM confirmed by TGA or XRD prior to blending into cement
- Clinker substitution ratio documented to substantiate the additional embodied-carbon reduction claim
- CO₂ source documentation and chain-of-custody, determining TTC-D versus TTC-R credit type classification
- Confirmation the same mineralised SCM tonnes are not separately registered under Annex F
Which emission sources must be counted
TTS v1.0 Module 3 requires a full lifecycle GHG emissions inventory within the project boundary, deducted from gross mineralised CO₂ to arrive at the Net TTC figure.
Measurement, reporting
& verification
Teravent's Science Advisory Board assesses each pathway against four MRV dimensions. Precast curing (COC-M01) benefits from a fully controlled process environment giving very high measurement confidence; ready-mix curing (COC-M02) carries somewhat lower confidence given field pour conditions.
CO₂ uptake is quantified via calibrated gas analysis at the curing chamber, batching plant dosing system, or SCM reactor, accurate to ±2%. Mineralisation is directly confirmed through thermogravimetric analysis (TGA) or X-ray diffraction (XRD) of representative product samples, quantifying the carbonate mineral content formed. Ready-mix curing (COC-M02) additionally requires core sampling from a representative subset of poured structures given the field conditions between batching and final cure. Compressive strength testing, conducted as standard concrete quality assurance practice, provides a secondary corroborating indicator of successful carbonation. All laboratory analyses must be conducted by an accredited facility, and gas metering instrumentation calibrated by an accredited VVB.
Demonstrating additionality
TTS v1.0 Module 2 requires all projects to pass a three-test additionality framework, with a Technology Readiness Level (TRL) screen applied ahead of the common practice test. Because CO₂ curing also improves compressive strength - a commercially valuable property independent of carbon credit revenue - the financial additionality test requires particular care to isolate the CO₂ injection system's incremental cost from the underlying commercial benefit of a stronger product.
Leakage types & deductions
TTS v1.0 Module 3 defines three leakage types applicable across all engineered pathways. CO₂ Concrete Curing carries relatively limited leakage exposure given its contained industrial process, primarily energy-source leakage and a CO₂ source double-counting consideration.
Buffer pool & reversal risk
All Annex J credits carry Class III Mineral permanence (>1,000-year storage horizon). Because mineralisation is confirmed directly through laboratory analysis of the finished concrete product, reversal risk for this pathway is very low once carbonation is verified. Buffer rates are set by the project's Storage Integrity Risk Rating (SIRR).
| Methodology | SIRR Rating | Buffer Pool Rate | Primary Reversal Risks |
|---|---|---|---|
| COC-M01 Precast | Very Low | 2–6% | Incomplete curing prior to product sale; product misclassification at end use |
| COC-M02 Ready-Mix | Low | 3–8% | Field pour conditions introduce curing variability relative to controlled chambers |
| COC-M03 SCM Treatment | Very Low | 2–7% | Cross-registration overlap risk with Annex F; incomplete curing prior to blending |
Key registration criteria
Projects must meet all of the following minimum requirements to qualify for registration under TTS Annex J. Additional methodology-specific requirements are detailed in the Annex J methodology tables for each COC-M code.
Sustainable Development
Goal alignment
All Teravent registered CO₂ Concrete Curing projects must complete an SDG impact assessment at registration and at each verification period. Three SDGs are systematically tracked for this pathway. Projects may apply for co-benefit quality labels where independently verified indicators are met.
Deployment scope: Global - precast and ready-mix concrete production facilities exist wherever construction activity occurs, making this one of the most geographically flexible and scalable pathways in the Teravent system given concrete's status as the world's most-consumed manufactured material.
Ready to register your
concrete curing project?
Submit a Project Concept Note under TTS v1.0 Annex J to begin your registration. Select the COC-M code matching your production format, document your CO₂ source to establish credit type, install calibrated gas metering, and appoint an accredited VVB to validate your PDD.