Metavolcanic Carbonate-Active Binder (MCAB): A Catalytically Tunable, Carbon-Negative Concrete System
Metavolcanic Carbonate-Active Binder (MCAB): A Catalytically Tunable, Carbon-Negative Concrete System
Abstract
This paper introduces the Metavolcanic Carbonate-Active Binder (MCAB), a concrete system formulated from finely milled metavolcanic-pozzolan co-blended with magnesium-silicate seeds (e.g., forsterite/serpentine) and sub-percent carbonate-catalyst ensembles (calcium/magnesium nano-carbonates with trace iron). The working hypothesis is that mesoscale nucleation control and interfacial ion transport can be tuned to accelerate the co-precipitation of carbonate minerals specifically calcite, aragonite, and hydromagnesite during curing, yielding predictable CO2 uptake while maintaining robust structural performance.
To explore this, a kinetic model is developed that links: (i) catalyst loading (0.1-1.0 wt%), (ii) ash reactivity index, and (iii) time-temperature-humidity profiles to the carbonation mineralization rate and early-age compressive strength. The model generates design maps targeting 10-20% CO2 uptake by mass within 24 hours, with predicted strength retention exceeding 80% of standard concrete despite a 70-90% replacement of Portland clinker.
The validation plan involves:
This paper introduces the Metavolcanic Carbonate-Active Binder (MCAB), a concrete system formulated from finely milled metavolcanic-pozzolan co-blended with magnesium-silicate seeds (e.g., forsterite/serpentine) and sub-percent carbonate-catalyst ensembles (calcium/magnesium nano-carbonates with trace iron). The working hypothesis is that mesoscale nucleation control and interfacial ion transport can be tuned to accelerate the co-precipitation of carbonate minerals specifically calcite, aragonite, and hydromagnesite during curing, yielding predictable CO2 uptake while maintaining robust structural performance.
To explore this, a kinetic model is developed that links: (i) catalyst loading (0.1-1.0 wt%), (ii) ash reactivity index, and (iii) time-temperature-humidity profiles to the carbonation mineralization rate and early-age compressive strength. The model generates design maps targeting 10-20% CO2 uptake by mass within 24 hours, with predicted strength retention exceeding 80% of standard concrete despite a 70-90% replacement of Portland clinker.
The validation plan involves:
- Synthesizing MCAB pastes at 0.30–0.45 water/binder ratios with 70–90% clinker substitution.
- Implementing both controlled CO2 curing (0.1–1 bar partial pressure) and ambient carbonation protocols.
- Quantifying CO2 uptake via thermogravimetric analysis (TGA/DSC) and a closed-loop CO2 mass balance system.
- Resolving carbonate polymorphs and silicate hydrate reaction products using X-ray diffraction with ATR-FTIR.
- Assessing evolution of the pore structure via Mercury Intrusion Porosimetry and N2 sorption.
- Measuring mechanical properties (compressive strength, fracture energy) and key durability indicators (chloride diffusion, sulfate resistance).
Anticipated outcomes from this research include: (a) tunable, catalyst-dependent mineralization kinetics; (b) 80% retention of the control compressive strength at 24 hours, despite high clinker replacement levels; and (c) an optimized process window (catalyst concentration, CO2 partial pressure, curing temperature) that maximizes carbon uptake without inducing micro-cracking or compromising long-term integrity. MCAB targets a ”drop-in” decarbonization solution for precast and cast-in-place workflows, translating laboratory design maps into production-ready curing recipes that deliver measurable, verifiable CO2 removal alongside structural reliability for the global construction industry.