Extrusion-based 3D printing nozzle system for in-situ CO₂ carbonation and sustainable cement fabrication

Background

The field of sustainable construction is exploring alternative binders to ordinary Portland cement (OPC) due to its high carbon footprint. Additive manufacturing of cementitious materials promises more efficient material use and design flexibility, but relies on precise control of paste rheology, curing, and strength development. Engineers seek processes that both sequester CO₂ during hardening and meet the early strength needs of construction schedules. Rapid carbonation of calcium‐silicate‐based binders could reduce CO₂ emissions and permit near‐real‐time fabrication of structural elements if optimized for diffusion and mechanical performance.

However, existing approaches struggle with uneven gas distribution and limited CO₂ penetration in thick layers, resulting in incomplete carbonation and weak interlayer interfaces. Many setups rely on post‐printing chambers or batch curing that slow production and increase complexity. High‐pressure CO₂ delivery often lacks precise control, causing gas leakage and safety concerns, while standard nozzles fail to maintain uniform flow across a printed surface. Moreover, formulations that balance extrudability and carbonation often require trade-offs that compromise build geometry or early mechanical strength, hindering scalability for larger, load-bearing components.

Technology

A 3D-printed PLA nozzle attachment clamps onto a standard extrusion system, delivering wollastonite-based cement paste through a central outlet and four peripheral CO₂-emitting nozzles fed from a high-pressure cylinder. The custom paste—engineered with a 0.4 water-to-cement ratio, superplasticizer, and viscosity-modifying admixtures—provides stable extrusion and shape retention. Layer-by-layer printing with lamellar and cellular infill patterns generates porous interfaces and high surface-area-to-volume ratios, promoting rapid CO₂ diffusion and in-situ carbonation. Integrated in-hose valves for precise flow control, adjustable nozzle angles, and an enclosed ventilation system ensure uniform gas distribution, operator safety, and efficient CO₂ use, enabling scalable fabrication of thick, low-carbon cement components.

This technology differentiates itself by merging additive manufacturing with on-the-fly carbonation, actively sequestering CO₂ within the material matrix during construction rather than relying solely on post-curing processes. The direct gas application onto freshly printed layers accelerates carbonation kinetics, achieving significant early-age strength gains compared to traditional cast calcium silicate cements. The cellular architecture amplifies CO₂ uptake by maximizing exposure surface, while precise process controls minimize waste and environmental impact. Modular nozzle design and a controlled printing environment further enhance reproducibility and scalability, delivering structurally robust cement elements with a markedly reduced carbon footprint.

Benefits

• Accelerated early strength development via in-line CO₂ carbonation
• Active CO₂ sequestration in cement paste, lowering overall carbon footprint
• Enhanced gas diffusion and hardening through porous, cellular infill architecture
• Precise CO₂ flow and nozzle angle control for uniform carbonation and material consistency
• Scalable 3D printing of thicker, low-carbon cement components
• Operator safety and CO₂ efficiency ensured by an enclosed ventilation system

Applications

• Carbonatable ceramic part printing
• Carbonated concrete block production
• Affordable housing component manufacturing
• Lightweight structural panel fabrication
• Custom architectural element printing

Additional info

A 3D-printing nozzle insert extrudes wollastonite-based cement paste while directing CO₂ onto each layer for in-situ carbonation. A clamp-on PLA adapter houses a central paste nozzle and four peripheral CO₂ outlets, with an in-hose valve and adjustable angles ensuring uniform gas delivery. Custom paste (w/c 0.4, superplasticizer, VMA) and cellular infill maximize surface area, accelerate hardening, improve early strength, and enable scalable, low-carbon component fabrication with integrated ventilation for safety.