Why low carbon concrete is not just an option

Yet this very material, so fundamental to our advancement, has traditionally had a significant carbon footprint. As head of innovation at Holcim, I am witnessing firsthand a profound shift in how we build. The question is no longer if we can build low-carbon infrastructure, but when we can make it the universal standard.

The demand for infrastructure across the world continues to rise, driven by urbanisation and the critical need to upgrade ageing networks. This means there is a need to fundamentally transform not what we build but how we build, prioritising low carbon concrete solutions, especially for the robust, enduring infrastructure that defines our societies. Our goal is clear: to accelerate the transition to sustainable construction. This isn’t just about incremental improvements; it’s about a paradigm shift in material science.

Holcim dedicates over 80% of its R&D efforts to sustainable and circular solutions. One of the most exciting recent developments is the integration of biochar into concrete – a building material that actively removes carbon from the atmosphere. In collaboration with architect Alejandro Aravena and his firm Elemental, Holcim has unveiled biochar-based concrete, which transforms buildings into carbon sinks.

Biochar is a charcoal-like substance, produced by pyrolysis of organic matter. Instead of decomposing and releasing CO2, carbon is sequestered within the biochar, which then becomes an integral part of our low-carbon cement, mortars, and concrete. Each kilogram of biochar can prevent the release of up to three kilograms of CO2. This technology isn’t just for niche applications; it’s designed to be scalable and applicable across all project types, from housing prototypes to the very infrastructure that underpins our modern lives. The potential for roads, bridges and tunnels to become active carbon capture mechanisms is transformative.

We are currently trialling this innovation in a number of pilot projects; but beyond that, our commitment to low-carbon solutions is embedded across our material products. Our low-carbon concrete (ECOPact) and low-carbon cement range (ECOPlanet) are examples, delivering at least 30% lower carbon footprint while maintaining 100% performance. This is achieved through innovative formulations, including the use of calcined clay and recycled construction and demolition materials.

For infrastructure projects, where durability and performance are critical and volume of material used impacts the overall carbon footprint, low carbon solutions already provide the backbone for sustainable construction. For example, Bordeaux’s 549m long, 44m wide Simone Veil Bridge designed by global architecture practice OMA was made possible through a combination of advanced engineering, technical delivery, and 4,000t of our low carbon cement, which reduced the CO2 footprint of the concrete foundations by 50%. From foundations to massive structural components, the material can be easily integrated, pumped, and finished like conventional concrete, providing a transition to more sustainable building practices.

We’re also supporting Melbourne’s largest-ever road project: the North East Link, designed to close the gap in the city’s orbital freeway network and change the way people move, by supplying approximately 350,000 to 400,000 m³ of low-carbon concrete, including an advanced solution containing 80% supplementary cementitious materials (SCMs) in non-structural applications. This accounts for nearly half of the project’s total 800,000 m³ required volume, and represents over 4,460 culverts for the 6.5km twin tunnels and related infrastructure. Each culvert incorporates 25% SMCs, reducing emissions without compromising strength.

Developing low-carbon materials is only one part of the equation; we must also embrace circularity within the construction industry. Concrete is infinitely recyclable. This is a powerful truth that we must fully harness. The linear “take, make, dispose” model is unsustainable and obsolete. Our focus must shift to a “reduce, recycle, regenerate” economy, where today’s waste becomes tomorrow’s valuable resource.

Last year, we incorporated 10.2M tonnes of construction and demolition materials (CDM) into new high-value building solutions. We are not just upcycling; we are truly closing the loop. With over 150 recycling ceres, strategically located near major metropolitan areas, we are transforming ‘urban mines’ into sources of raw materials. These products can contain anywhere from 10% to 100% recycled content, all while maintaining uncompromising quality and performance.

This significantly reduces the need for virgin aggregates and lessens the burden on landfills. It’s a win-win: preserving natural resources, reducing waste, and simultaneously cutting carbon emissions associated with material extraction and processing. The embodied carbon savings from recycling concrete can be substantial, preventing the need for new material production and its associated CO2 output. This is not just about environmental benefit; it’s about economic efficiency and resource security.

Undoubtedly there are challenges. Overcoming outdated building codes and industry norms, which often prioritise conventional materials, is a constant battle. We need governments and regulatory bodies to incentivise the adoption of low carbon and circular solutions, recognising their long-term value not just for the planet, but for the resilience and longevity of our infrastructure.

The future of construction must be sustainable. I am convinced that the path forward lies in radical innovation, a relentless pursuit of lower-carbon alternatives, and embracing circular economy principles. Solutions to decarbonise the industry are no longer futuristic concepts; they are here, ready to be deployed at scale.

• Edelio Bermejo is head of group R&D and innovation at Holcim