Post Cure CO₂ Absorption and Carbonation

Unlike traditional concrete, zeolite concrete continues to interact with atmospheric CO₂ even after curing. CO₂ diffuses into the concrete pores and reacts with calcium (Ca) in the zeolite concrete to form calcium carbonate (CaCO₃), a stable compound that remains locked in the concrete. Our zeolite concrete composite captures and stores atmospheric CO2 through a carbonation reaction. Once absorbed, the carbon further enhances the materials’ properties.

Step-by-Step Breakdown

1. Atmospheric CO₂ is absorbed by the cured zeolite concrete composite and reacts with calcium ions in zeolite.
2. This forms calcium carbonate (Ca + CO₂ = CaCO₃) which is sequestered permanently, even if the concrete is demolished.
3. The mineralization process creates nanoscale calcium carbonate particles, resulting in enhanced compressive strength.

Carbon Capture Efficiency

• A 15×15×15 cm zeolite concrete block can absorb approximately 1 mole of CO₂ (approximately 44 grams). One mole of carbon dioxide (CO₂) weighs 44.01 grams. Every mole of CO₂ captured from the atmosphere represents 44.01 grams of gas permanently sequestered.  NOTE1: Carbon (C) has an atomic mass of about 12.01 g/mol.  NOTE2: Oxygen (O) has an atomic mass of about 16.00 g/mol.

Eco-Friendly Benefits

• Carbon Sink: Zeolite concrete acts as a passive carbon sink, reducing ambient CO₂ levels.
• Durability: The formation of CaCO₃ improves microstructure and reduces porosity/permeability.
• Sustainability: It offers a dual benefit lower  cement usage and active carbon sequestration.

Applications

• Ready-mix concrete.
• Precast concrete products.
• 3D concrete printing

Clinoptilolite zeolite (Zeolite) is a potent supplementary cementitious material (SCM) with high reactivity, abundant pozzolanic activity, and the smallest net carbon footprint compared to other SCMs. While carbonation has been explored as a potential approach for strengthening concrete made with Ordinary Portland Cement (Cement), the opportunity for synergistic reactions involving Zeolite and carbonation have been underexplored. The effect of Zeolite on the initial hydration kinetics was studied by the University of Washington Department of Materials Science & Engineering, and the resulting composition, microstructure and strength were assessed for up to 30% Cement replacement (CR) with Zeolite increases strength development relative to non-zeolite Cement concrete by as much as 40% over 91 days of curing. Carbonation accelerates the increase in compressive strength, promoting over 30% increase in strength (at 20% CR) after only 4 weeks. Carbonation also mitigates loss in strength for mixes with higher zeolite concentrations up to 30% CR. Carbonation results in formation of a densified outer “shell” of carbonated material and reduction in overall porosity and pore size. Post cure carbonation can improve the properties of concrete and precast concrete products that use clinoptilolite zeolite as an SCM for CR.