CO₂-Nomicom — Carbonated Recycled Crushed Stone Aggregate

Problem solved

Construction demolition waste (concrete-ga ra) constitutes a major waste stream, and conventional recycling produces aggregate that still has a net carbon footprint from crushing and transport. CO₂-Nomicom converts the calcium-rich cement paste fraction into a CO₂ sink via accelerated carbonation, producing a carbon-negative recycled aggregate that can replace virgin crushed stone in civil engineering applications.

Application contexts

• Road base and subbase for public infrastructure projects under green procurement
• Backfill material for retaining walls and foundation works
• Precast concrete secondary products (blocks, pavers) with embedded CO₂
• Carbon sequestration as a co-benefit of mandatory construction waste recycling

Technical principle

Concrete demolition waste is crushed and graded into recycled aggregate. During processing, the material is exposed to controlled CO₂ atmosphere in a carbonation chamber. Calcium hydroxide (Ca(OH)₂) and calcium silicate hydrate (C-S-H) from the residual cement paste in the recycled aggregate react with CO₂ to form calcium carbonate (CaCO₃), permanently fixing CO₂ in the solid phase. The carbonated aggregate also shows improved particle density and reduced water absorption compared to standard recycled aggregate.

Typical use cases

• Carbon-negative road base material for public road projects with embodied-carbon limits
• CO₂-sequestering backfill for building foundation works in urban redevelopment
• Aggregate for precast concrete blocks with verified CO₂ fixation credits