Industrial carbon dioxide

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Carbon dioxide (CO₂) is widely recognized by the general public as a greenhouse gas and a primary driver of global warming. However, in modern engineering literature, this simple molecule is gradually undergoing a repositioning. What was once considered a low-value or even troublesome byproduct in petrochemical, steel, cement, and power generation industries has now become a strategic raw material for producing low-carbon construction materials. One of the most significant manifestations of this transformation is the development of carbon-absorbing concrete technologies—concrete that not only has a lower carbon footprint but also permanently stabilizes a portion of industrial CO₂ within its structure.

The cement industry alone accounts for approximately 7–8% of global CO₂ emissions (according to reports by the International Energy Agency). Therefore, any innovation capable of reforming this industry’s carbon cycle will have global impact. Modern concrete carbonation technologies, through controlled injection of industrial CO₂ during early mixing or curing stages, enable stable chemical reactions that form calcium carbonate. This process not only stabilizes carbon but can also improve the mechanical properties of concrete.

This article analytically and descriptively examines the transformation of industrial carbon dioxide from a byproduct into a valuable input in the construction industry and analyzes the role of industrial gas suppliers in shaping this new value chain.

Today’s world stands in the midst of a major industrial transition—one centered on redefining the relationship between production, energy, and the environment. For more than a century, industrial growth was largely based on extraction, consumption, and emission. Fossil fuels were extracted, energy was generated, industrial products were manufactured, and combustion gases were released into the atmosphere without serious concern. Now, this linear model is giving way to a circular perspective—one in which “waste” can become “raw material.”

Carbon dioxide is a clear example of this paradigm shift. In the past, CO₂ was merely regarded as a byproduct of processes such as natural gas reforming, combustion in power plants, or calcination in cement factories. Its management primarily meant disposal, release, or at best underground storage. With the development of carbon capture, utilization, and storage (CCUS) technologies, a new perspective emerged: can CO₂ be treated as an engineered raw material?

At this point, the concrete industry enters the picture. Concrete is the most widely used manufactured material on Earth—the backbone of cities, bridges, dams, and buildings. Yet its production depends on cement, and cement manufacturing is one of the largest sources of industrial CO₂ emissions. The paradox is clear: an industry responsible for significant carbon emissions may also become a platform for carbon stabilization.

New accelerated carbonation technologies enable the injection and stabilization of industrial CO₂ within the microscopic structure of concrete. Companies such as CarbonCure Technologies and Solidia Technologies have demonstrated that emission reductions, strength improvements, and economic value creation can be achieved simultaneously.

From a business perspective, this transformation presents a strategic opportunity for industrial gas and gas condensate companies. CO₂ is no longer just a gas for food processing or welding applications—it is becoming a specialized input in sustainable construction. This shift creates a new supply chain involving purification, compression, storage, and targeted CO₂ distribution.

Nature of Industrial Carbon Dioxide and Recovery Processes

Industrial CO₂ is typically recovered from exhaust streams of large industries. Major sources include ammonia production units, refineries, thermal power plants, steel industries, and cement factories. In many of these facilities, CO₂ is produced at relatively high purity and requires only separation, drying, and compression.

In petrochemical industries—especially steam methane reforming units for hydrogen production—CO₂ is an unavoidable byproduct. In industrialized countries, a significant share of commercial CO₂ is sourced from such operations. Purity, pressure, storage temperature, and impurity levels are key parameters in advanced applications such as carbonated concrete.

The Cement Industry: The Core of Carbon Emissions

Portland cement production is based on heating limestone (calcium carbonate) at high temperatures. The calcination reaction directly releases CO₂. Additionally, fossil fuels consumed in kilns create further emissions.

According to data published by the Global Cement and Concrete Association, global demand for concrete continues to grow, particularly in developing countries. Without technological change, emissions from this sector will persist.

Therefore, any solution capable of either reducing cement consumption or re-stabilizing emitted CO₂ in the final product is strategically important.

Chemical Mechanism of Concrete Carbonation

In traditional concrete, cement hydration reactions produce calcium hydroxide and C-S-H gel. The presence of CO₂ leads to reaction with calcium hydroxide and formation of calcium carbonate. Naturally, this process occurs over years; in modern technologies, it is controlled and accelerated.

Injecting CO₂ during mixing or curing produces ultra-fine calcium carbonate particles that densify the cement matrix. This densification can increase early compressive strength and enable reduction of cement usage.

Innovative Carbon-Absorbing Concrete Technologies

Two primary approaches exist:

1. CO₂ injection into fresh concrete
2. Curing concrete in a CO₂-rich environment

CarbonCure Technologies focuses on micro-dose CO₂ injection during mixing, while technologies developed by Solidia Technologies rely on modified cement chemistry and CO₂ curing environments.

Both approaches share a common goal: permanent stabilization of CO₂ in stable calcium carbonate form.

Life Cycle Assessment and Real Emission Reduction

The key question is whether carbon-absorbing concrete truly reduces net emissions. The answer is determined through Life Cycle Assessment (LCA). Studies indicate that when cement reduction and CO₂ stabilization occur simultaneously, emissions per cubic meter of concrete can decrease by 5–20%, depending on technology and production conditions.

Technical and Microstructural Analysis

Microstructure of Carbonated Concrete

To truly understand the value of CO₂ injection technology, one must examine the microscopic structure of concrete. Concrete consists of hydrated cement paste, aggregates, and interfacial phases. Strength and durability largely depend on the structure and porosity of the cement paste phase.

During cement hydration, clinker compounds (C₃S and C₂S) react with water to form C-S-H gel and calcium hydroxide (Ca(OH)₂). C-S-H gel is the primary strength-bearing phase, while calcium hydroxide is weaker and relatively more soluble.

When industrial CO₂ is injected into fresh concrete, the following reaction occurs:

Ca²⁺ + CO₂ + H₂O → CaCO₃

Ultra-fine calcium carbonate nanoparticles form during this reaction. These particles:

• Act as nucleation sites for C-S-H gel
• Fill microscopic pores
• Densify the cement paste structure

The result is reduced porosity and increased early compressive strength. Unlike natural carbonation, which occurs over years from the surface inward, this process happens uniformly throughout the entire volume at the beginning of concrete’s life.

Microscopic studies using SEM and XRD in research projects related to CarbonCure Technologies have shown that the formed carbonate is stable and permanently embedded within the matrix.

Mechanical Properties and Long-Term Durability

Initial concerns suggested CO₂ injection might negatively affect long-term durability. However, laboratory data indicate that when properly controlled, durability is maintained or even improved.

Reported 28-day compressive strength increases range from 5–10%. This allows producers to reduce cement content—directly lowering carbon footprint.

From a durability standpoint:

• Permeability decreases
• Resistance to freeze–thaw cycles improves
• Early shrinkage is reduced

Precise dosage control remains essential.

Comparison of CO₂ Stabilization Technologies in Concrete

Table 1 – Comparison of Major CO₂ Stabilization Technologies in the Concrete Industry

Global Market and Future Outlook

The low-carbon construction materials market is rapidly expanding. Climate policies, carbon taxation, and ESG requirements are increasing demand for low-emission concrete.

Climate initiatives in the European Union, emission reduction commitments in North America, and net-zero targets by 2050 pursued by institutions such as the United Nations support the growth of this technology.

In the coming decade:

• Cement plants are expected to integrate CO₂ capture and reuse
• Carbonated concrete may become standard in major infrastructure projects
• A new market for construction-grade industrial CO₂ will emerge

This transformation converts CO₂ from an environmental cost into an industrial asset.

Analytical Conclusion

The transformation of industrial carbon dioxide represents one of the clearest paradigm shifts in the carbon economy. A decade ago, CO₂ was primarily seen as a problem—a gas to be controlled or stored underground. Today, with advances in carbon utilization technologies, this simple molecule has become part of the solution.

Reports by the International Energy Agency emphasize that achieving net-zero targets is nearly impossible without reforming cement and concrete technologies.

Carbon-absorbing concrete activates two emission-reduction pathways simultaneously:

• Direct stabilization of industrial CO₂
• Indirect reduction through lower cement consumption

The growth of CarbonCure Technologies and Solidia Technologies demonstrates that this technology has entered the commercial phase. Institutions such as the Global Cement and Concrete Association and the United Nations actively support decarbonization in construction.

Ultimately, the future of construction is moving toward carbon-neutral—or even carbon-negative—models. In that future, industrial CO₂ is no longer the end of the production chain, but the starting point of a new value cycle.

References

• International Energy Agency (IEA). Cement Technology Roadmap and Net Zero by 2050 Reports.
• Global Cement and Concrete Association. Concrete Future – The GCCA 2050 Net Zero Roadmap.
• CarbonCure Technologies. Technical White Papers and Performance Reports.
• Solidia Technologies. Sustainability and CO₂-Cured Concrete Publications.
• United Nations. Climate Action and Net Zero Industry Frameworks.
• IPCC. Sixth Assessment Report – Mitigation of Climate Change.
• Journal of CO₂ Utilization. Peer-reviewed articles on mineral carbonation in cementitious materials.
• Cement and Concrete Research Journal. Studies on accelerated carbonation curing.