The need to reduce the construction industry's carbon footprint and its reliance on virgin natural resources is the most pressing issue facing the sector. It is therefore extremely important to foster innovation that can improve existing building materials and make them environmentally friendly, in order to successfully tackle its sizable carbon footprint and close the material loop.
Concrete, for example, has been used since the times of the ancient Romans and has proven to be a durable, strong, affordable and versatile building material. Today, it is the most widely used man-made resource in the world. However, its production methods raise environmental concerns: firstly, due to the high consumption of natural resources such as sand and gravel; and secondly —and more importantly— because of the CO₂ emissions associated with the production of its key ingredient: cement.
With the continued growth of cities and the rising rate of urbanization around the world, the demand for both cement and concrete will continue to increase, highlighting the importance of innovations in the construction industry to make these materials more resource-efficient and environmentally friendly.
Traditionally an industry that has been slow to change, companies within the construction sector are becoming increasingly aware of their role in the future of making cement and concrete into sustainable building materials. Holcim —a multinational of Swiss origin and a global leader in innovative and sustainable building solutions— has mapped out a new focus on reducing carbon emissions, optimizing the use of materials, and promoting a collaborative innovation ecosystem to decarbonize the industry and make it more circular.
It All Starts With Cement
The decarbonization of concrete starts with cement. One of the milestones on the journey to making it more sustainable has been the development of ECOPlanet cement, which seeks to provide a lower-carbon building material without compromising on performance. It is created by substituting clinker —which is the main component of cement and which emits large amounts of CO₂ when limestone is calcinated— with raw materials such as calcined clay that require much lower temperatures for calcination or demolition materials.
Another way that cement production creates CO₂ emissions is by burning fossil fuels to heat the kilns to extremely high temperatures. This is now being reduced with the use of renewable energy sources, improved process efficiency and digitization.
It is through these actions that the ECOPlanet low-carbon cement range is able to offer the full performance of traditional cement, but with a fraction of the carbon footprint. One example is the new administrative capital of Egypt, currently under construction outside Cairo, where the Iconic Tower will be the tallest in Africa. Built using ECOPlanet cement, the new development will result in a savings of over 6,800 tons of CO₂ emissions, equivalent to a CO₂ reduction of 60%, without compromising performance, strength, or durability. Another example comes from Seattle, where the iconic Spheres building achieved over 80% reduction in CO₂ emissions compared to industry averages, saving up to 400 tons of CO₂ and earning a LEED Gold certification.
Once all other possible decarbonization methods are employed, cement manufacturers could also prevent those emissions that cannot be avoided with the help of next-generation technologies such as carbon capture, utilization and storage (CCUS).
Concrete CO₂ and Material Savings
Complementing the ECOPlanet low-carbon cement range is ECOPact, the industry’s broadest offering of low-carbon concrete for sustainable construction. It is sold at a range of low-carbon levels starting at 30% lower embedded carbon compared to standard (CEM I) concrete, has equal or better properties than conventional concrete, is available in a variety of strength classes, and is compliant with industry standards. It has already been used in construction projects around the world –from Latin America’s longest dam to Boston University’s Data Science Center– to achieve significant CO₂ savings while delivering 100% performance.
Another breakthrough was developed at Holcim’s Altkirch plant in France, focusing on one of the primary components in cement production: 100% recycled clinker. Typically manufactured in highly controlled industrial processes that are conventionally based on extracted limestone and other raw materials, it plays a key role in cement due to its compressive strength — a critical attribute of concrete. The study marked a significant departure from this conventional approach by using 100% exclusively recycled materials, ranging from wood ash to mineral processing by-products, with a strong emphasis on locally sourced inputs.
The vision for 100% recycled clinker was to make 100% recycled cement, followed by 100% recycled concrete. That vision is now culminating in “Recygénie”, the world's first fully recycled concrete building. This social housing complex comprising 220 units near Paris, France exemplifies the transformative potential of Holcim's custom concrete, crafted through the application of ECOCycle® technology. This revolutionary concrete incorporates recycled elements, such as cement, aggregates, and water, effectively repurposing construction and demolition waste into sustainable construction materials. It represents an environmentally conscious approach that translates into significant resource savings, with the Recygénie project alone preserving over 6,000 tons of natural resources.
Building components —such as beams and slabs— also have the potential to improve their environmental credentials with the help of innovation. In 2020, Holcim invested in the Swiss startup CPC AG, which introduced the Carbon Prestressed Concrete (CPC) technology. These are slabs created using a patented technology that offer the same load-bearing capacity as traditional reinforced concrete slabs, but with the notable advantage of being five times thinner and lighter, due to the addition of carbon filaments instead of traditional reinforcements. Not only does the absence of steel components result in a longer service life (potentially up to 100 years), but it also allows for disassembly and reuse or complete recycling of CPC systems. It also reduces material usage by up to 80% and CO₂ emissions by up to 75%, which facilitates industrialized, circular, low-carbon building practices.
The Eulach footbridge, located in Winterthur, Switzerland, demonstrates the possibilities of CPC use. Typically, a bridge of similar length built with traditional reinforced concrete would weigh approximately 56 tons (including its foundation); and an equivalent wooden bridge would weigh around 26 tons. On the other hand, the footbridge made with CPC is surprisingly light, weighing just 14 tons. This represents a 75% reduction compared to traditional concrete, and a 46% reduction compared to wood. Furthermore, over its entire lifetime, the CPC bridge exhibits a carbon footprint that is up to five times smaller than a conventional concrete bridge and up to three times smaller than one made of wood.
Fostering a Culture of Innovation
If it is to truly reinvent how the world builds, the commitment to sustainability in the construction industry must ramp up product innovation, which should then make the leap to tangible construction methods. In a partnership between Holcim and British International Investment (BII), 14Trees has been pioneering building solutions that are both sustainable and affordable.
This collaborative venture has 3D-printed ten housing units in Kenya, making it the largest affordable 3D housing project to date. Using cutting-edge 3D printing technology, the walls of a two-bedroom house take just 18 hours to complete, providing a fast and efficient alternative. Each phase of the project's development introduces new innovations, from the architectural design emphasizing comfort and climate adaptability to the use of efficient materials and customization for future tenants, while seeking a 20% reduction of cost compared to standard housing units. The project’s advanced sustainability profile has attained an IFC-EDGE Advanced sustainable design certification by The World Bank.
Collaboration and knowledge sharing are key to the sustainable future of construction. The newly established Holcim Innovation Hub is a mix of spaces that include a showroom that showcases its sustainable solutions, co-working spaces and an events area that serves as a platform for co-creation and collaboration. It is a space where ideas converge, partnerships are formed and progress is achieved. In essence, Holcim's emphasis on innovation spans multiple dimensions: from cutting-edge technologies and sustainable material formulations to circular design principles and spaces for innovation and collaboration to thrive.
Visits for professionals from the construction industry are available upon request. More info here.
This article is part of the ArchDaily Topics: Decarbonize Architecture presented by Holcim.
Driven by its purpose to build progress for people and the planet, Holcim is decarbonizing building, while improving living standards for all. Holcim empowers architects and developers across all regions to build sustainably. This series explores how cities of the future can be low-carbon, circular and resilient.
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