Towards Carbon Neutrality: African Infrastructure Projects Tackling Embodied Carbon

As Africa rapidly expands its infrastructure networks to meet growing demand, there is a pressing need to address the embodied carbon—the hidden carbon emissions associated with construction materials, processes, and systems used to build roads, dams, railways, and other critical infrastructure. While much of the focus has been on reducing operational carbon during the use phase of infrastructure, embodied carbon can account for a significant portion of a project's total emissions, particularly in resource-intensive sectors like transportation and water management.

Reducing embodied carbon requires innovative approaches that prioritize sustainable materials, local sourcing, energy-efficient construction methods, and circular economy principles. Across Africa, a number of forward-thinking projects are tackling embodied carbon head-on, setting an example for how large-scale infrastructure can be developed with minimal environmental impact. This article highlights practical examples of roads and dam projects across the continent that are embracing low-carbon solutions to build a more sustainable future.

These projects showcase Africa's commitment to decarbonizing its infrastructure and addressing climate change while continuing to develop the vital systems needed for economic growth and societal well-being.

1. Ethiopia: Modjo-Hawassa Expressway Using Low-Carbon Cement

• Overview: The Modjo-Hawassa Expressway is part of Ethiopia’s flagship road expansion project aimed at connecting its southern regions. The expressway project uses low-carbon cement alternatives in road construction, such as quicklime soil stabilization , which helps reduce the high emissions typically associated with Portland cement.

Key Benefits :

• Resource Conservation: Lime stabilization reduces the need for extensive excavation and replacement of unsuitable soils. By improving the existing soil’s properties, there is less reliance on importing new materials, thereby conserving natural resources and reducing transportation-related carbon emissions.
• Erosion Control and Water Management: Lime decreases soil permeability, preventing water infiltration that can weaken soil structures. This is particularly beneficial in flood-prone areas and helps to control erosion, reduce sediment runoff, and protect nearby water bodies from contamination.
• Waste Reduction: Lime stabilization enables the reuse of marginal or contaminated soils, which would otherwise be disposed of in landfills. This practice not only reduces waste but also minimizes the environmental impact associated with soil disposal.

Kenya: SASOL Sand Dam Projects in Kitui

• Overview: The SASOL sand dam projects in Kitui, Kenya, are a community-led initiative to improve water security and sustainability in arid areas. Sand dams are barriers constructed across riverbeds, capturing sand and water runoff during short but intense rainfall periods. The dams store water in the sand and recharge the surrounding groundwater, providing a long-term, sustainable water source.

• Embodied Carbon Reduction: Unlike earth dams and boreholes, sand dams use minimal materials such as locally sourced stones and concrete. They rely on simple, low-tech construction methods, reducing the need for energy-intensive machinery and transport of building materials. The embodied carbon footprint is kept low through community-based labor and the use of local resources.
• Key Benefits:

This innovative approach addresses both water scarcity and sustainability, with a focus on low-carbon, community-driven infrastructure solutions.

Zambia: Kazungula Bridge Using Precast Concrete Elements

• Overview: The Kazungula Bridge, connecting Zambia and Botswana, uses precast concrete elements, reducing the energy required for onsite construction and minimizing wastage of materials.

• Embodied Carbon Reduction: Pre-casting concrete in controlled environments reduces the overall energy consumption and emissions compared to traditional onsite pouring methods. Additionally, it lowers material waste, cutting down the embodied carbon.
• Key Benefits: Reduction in embodied energy, minimized material wastage, and efficient use of resources in bridge construction.

Here is another notable infrastructure project that can offer some additional insights on the matter:

Colombia: Reinforced Recycled Asphalt Pavement Rehabilitates Roads

• Overview: The Institute of Urban Development (IDU) of Bogota decided to rehabilitate run-down road infrastructure, integrating Recycled Asphalt Pavement (RAP) technology with reinforced with Neoloy Tough-Cell base layer to reduce the carbon footprint of new road construction. RAP uses reclaimed asphalt material from existing roads, which is then repurposed into new asphalt layers.
• Embodied Carbon Reduction: By recycling asphalt, the project minimized the need for new bitumen production, which is a carbon-intensive process. Additionally, it reduced waste and the embodied energy associated with material extraction and transportation.
• Key Benefits: The improved modulus of RAP also enabled a reduction in the overall thickness of the pavement structure. In addition to the 10% net savings, the project construction was faster as excavation, infill and compacting were all reduced.

Conclusion: Infrastructure Embodied Carbon – A Critical Front in the Climate Fight

As Africa continues to expand its infrastructure networks in roads, dams, railways, and pipelines, reducing embodied carbon is becoming just as important as managing operational emissions. By embracing recycled materials, local sourcing, low-carbon cement, and innovative construction techniques, these projects showcase how Africa is tackling the hidden carbon footprint of infrastructure, creating a path toward a more sustainable and resilient future.