Every year we make enough concrete to build a wall around the earth

Each year, humanity pours enough concrete to build a wall completely encircling the planet. This astonishing fact underscores concrete’s status as the world’s most used man-made material. From skyscrapers and bridges to pavements and houses, concrete shapes almost every aspect of modern infrastructure, but it comes with significant consequences - for the environment, engineering and urbanisation, writes John Ridgeway.

Concrete accounts for roughly 25 billion tonnes of production annually. To visualise its scale: imagine a continuous barrier, about one metre thick, stretching over 40,000 kilometres - essentially wrapping the entire globe. Despite its common presence, few pause to consider its vast scale and overwhelming influence.

This mass of concrete supports essential infrastructure such as roads that connect cities, dams that manage rivers, tunnels that support transport and foundations anchored deep into the earth. Its strength, durability and adaptability have transformed construction practices and enabled societies to expand vertically and horizontally.

Rapid urbanisation in developing regions creates a steady demand for new buildings, housing and public transport systems. Meanwhile, ageing infrastructure in developed countries requires ongoing replacement and renewal. In both contexts, concrete remains the default material - affordable, locally sourced and well understood by engineers.

Moreover, evolving safety and climate standards push increasingly stringent performance requirements. Whether in seismic zones or flood-prone areas, engineered concrete enables designers to meet demanding structural and regulatory needs. It also functions as an excellent thermal mass, helping regulate internal temperatures in diverse climates.

The environmental impact

However, concrete’s global consumption carries a heavy environmental burden. Cement - the key ingredient in concrete - is responsible for about 7% of global CO₂ emissions. Producing one tonne of cement contributes approximately 0.9 tonnes of CO₂, derived primarily from decarbonising limestone and burning fossil fuels.

In addition to greenhouse gases, concrete contributes to resource depletion, dust pollution, and vast quarrying footprints. Water use and waste management are mounting concerns, especially in areas facing environmental stress. Without radical innovation, these impacts only increase in line with concrete’s production.

Recognising the urgency, the industry has introduced greener concrete solutions such as low-carbon cements including geopolymer formulations, blended cements with fly ash or slag and novel binders that reduce CO₂ emissions per tonne. Recycled aggregates sourced from demolished buildings or industrial byproducts, are shrinking dependence on virgin materials. Carbon capture technologies are also being integrated into cement plants and ready-mix production lines.

Concrete has traditionally been used in its basic form. Now, with the advent of high-strength mixes, ultra-high-performance concrete (UHPC) and 3D printing technologies, its use is being reimagined at every level - from beams and panels to entire building shells. These materials enable slimmer, lighter structures with equal or greater strength, reducing both material use and embodied carbon per structure. Ultra-early-strength programmes and modular precast systems are further reducing on-site disruption, accelerating construction schedules and improving building quality.

Global implications

That said, constructing a global wall of concrete is more than a striking metaphor - it’s a sobering reality tied to our infrastructure dependency. As global GDP grows and cities intensify, global concrete use will climb further. If unchecked, that means more cement production, higher emissions and greater resource extraction - unless sustainable practices become standard.

Regulators, developers, engineers and governments must collaborate to accelerate low-carbon solutions. Public sector procurement should reward low-embodied-carbon materials. Research funding should prioritise scalable decarbonisation technologies and infrastructure planning must place resource efficiency at the core.

Every engineer or architect specifying concrete plays a critical role in reducing embodied carbon by requesting low-carbon cement alternatives, recycled aggregate content, optimised mix designs and performance-based specifications to help reshape procurement norms.

For the moment, the massive volume of concrete poured each year ensures extraction and waste will continue, although circular strategies do offer some hope. Selective demolition, for example, instead of pulverisation preserves reuse value. Deconstruction-based architecture can also ensure that future reuse is built in. Carbon-removal technologies that embed captured CO₂ within concrete blocks, turning emissions into permanent sequestration, are another option.

Lessons from Resilience and Extreme Design

Concrete’s role is not just volumetric—it’s structural. Seismic-resistant buildings use high-strength, ductile concrete. Offshore platforms depend on specific mixes resistant to chloride-driven corrosion. Urban mega-developments with post-tensioned slabs maximise structural performance while using less material.

Advanced structural glazing, carbon fibre-reinforced concrete, and 3D-printed forms link concrete’s strength with design flexibility once thought impossible.

There is no doubt that built environment professionals must confront this reality. Pouring cement in quantities sufficient to circle the Earth has serious consequences, for while improved regulations, advanced research and industry guidance are moving the sector closer to lower-carbon norms, progress is uneven.

Sustainable architecture and engineering will increasingly involve specifying carbon budgets for concrete use, auditing every ton of material. Oversight through environmental product declarations (EPDs), embodied carbon declarations (ECDs) and sustainable certifications is becoming the standard. Powers in Europe and North America are tying infrastructure funding to emissions reductions, pushing whole supply chains to innovate or lose contracts.

What the future looks like

Concrete won’t disappear because it remains unrivalled in performance, affordability and structural reliability. The future, however, will look different with smarter mix designs that safely minimise cement content. Other factors include prefabrication and modular construction which continues to dominate mainstream housing and infrastructure.

On-site blending and logistics to reduce transport emissions, localised cement plants with solar-powered operations and integrated carbon capture and policy frameworks that reward BREF (Best Practice Energy Reduction) products and circular construction, will all play their part.

The concept of a concrete wall encircling the Earth may be staggering, but it serves as a warning that our demand for infrastructure must evolve. Architects, engineers, developers, and clients all play a role in enabling that shift. Construction professionals who embrace low-carbon alternatives, who demand better materials and design for longevity, can turn this reality into an opportunity for innovation, creating buildings that stand the test of time without weighing down the planet.