If concrete was a country, it would have been the world’s third-largest carbon dioxide emitter behind only China and the US. This is no surprise given that it is the second most used material in the globe after water, it produces roughly 8% of greenhouse gas emissions. Decarbonization of concrete is essential to meeting the UN net zero targets.
GCCA, an association of the key concrete producers, set a goal of achieving net zero emissions by 2050 identifying the 2020–2050 decade as the period to find new clean technologies and laying the groundwork for full deployment. The industry low level of R&D has increased in recent years and venture investments into the industry has but they still fall short of the size of the problem.
The construction industry contributes around 38% of global house emissions compared to 23% contributed by the transportation industry. Yet, climate related venture investments into built environment were only $2bn in 2022, less than fifth of the $12bn received by the transportation industry. Governments are increasingly adopting policies to mandate adoption of green concrete and with the industry commitment, we see a path for investment in the industry to continue growing at double digits over the coming decade. The pursuit of a greener $300bn concrete market is in progress.
Making Concrete Greener by Changing Its Components
Cement, a key component of concrete, is available in various forms, although the most common are Portland clinker, gypsum, supplementary cementitious materials (SCMs), and fillers. Portland clinker makes up more than 98% of worldwide concrete production today. There are several reasons for this, including the fact that it is inexpensive, dependable, and creates high-quality concrete.
Process emissions released from the calcination of limestone to produce Portland clinker account for more than 50% of the cement sector’s emissions. A further 40% stems from burning fossil fuels to heat cement kilns to high temperatures throughout production. Cement naturally emits CO2 into the atmosphere as a result of cement production. This CO2 release is a by-product of the heat required to produce the cement and an inherent part of the chemical process.
A growing number of companies are focusing on reducing the carbon footprint of the production process by changing its components. Hoffmann Green Cement Technologies, established in France, develops, manufactures, and distributes novel clinker-free low-carbon cement with a carbon footprint six times that of standard PORTLAND cement. The company’s H-IONA cement is manufactured mainly from industrial by-products like steelworks slag to reduce waste and emissions, resulting in a decarbonate clinker.
Ecocem, which received a €22m investment from Bill Gates’s climate fund in 2021, has pioneered a cement based on ground granulated blast furnace slag (GGBS), a steel industry by-product. With the company’s low-carbon concrete product, up to 70% of the cement can get replaced, reducing the overall emissions by a similar amount.
Other innovative companies are endeavouring to capture the carbon inside concrete or directly capture the CO2 emitted during production. CarbiCrete is a Canadian company that has developed a technology for producing carbon-negative concrete through a patented process that removes more CO2 than it emits. This process uses CO2 from industrial sources to make a lower-carbon binder for concrete, reducing the overall carbon footprint of concrete production and creating a more sustainable product.
Some companies have created solutions to make greener aggregates used in construction. Neolithe is a French company that developed a fossilisation technology to transform waste into aggregates. This process reduces CO2 emissions from wasted materials by grinding the un-recycled materials in a fossiliser and mixing them with a waste powder and a low-carbon binder. The result is a stone paste which is then processed into a decarbonate aggregate for use in public construction. So far, the company has sold one unit, so it will need to scale up to demonstrate its technology’s benefits.
While we’ve seen progress in developing greener cement, considerable obstacles to broader adoption remain. Consumers tend to be wary of less tried and tested products, which has caused resistance to the technology, particularly in a sector that prioritises safety. New technologies must also grow and scale to attract external funding. Although implementing carbon pricing could stimulate investment in low-carbon cement in its early stages, it’s unlikely to reach high enough levels in major markets such as the EU, China, India, and the US anytime soon. Public financing and a shift in mindset from low-tech to low-carbon cement will be required to advance the industry.
Replacing Concrete with Cleaner Substitutes
Aside from modifying concrete components, innovative start-ups are working on creating concrete replacements or different types of concrete. Mighty Buildings is an American company that has developed a 3D printing machine that enables the creation of building structures from photopolymer resins. These polymer composites are as strong as concrete but are 30% lighter and have 5 X tensile and flexural strength. This results in a more environmentally friendly and speedier construction process and the ability to produce sophisticated architectural designs that are impossible with traditional concrete construction.
French company XtreeE has developed large-scale 3D printing technology for sustainable building solutions. The company is agnostic regarding printable materials with its bi-component systems able to extrude various mortars, including earth-based materials, plaster and geopolymers.
COBOD printers offer automation and robotics solutions, enabling the construction industry to improve printing speed, efficiency, labour need, and material cost. The company also provides a range of materials depending on the specific project’s performance standards. COBOD 3D printed Europe’s first building in 2017. Subsequently the first 2- and 3-story buildings in Europe, specifically in Belgium and Germany were made with their technology.
While 3D printing technology is gaining momentum in the cement and construction industries, it can be more expensive than traditional manufacturing methods, especially for large-scale production. Additionally, limited materials are available for 3D printing and the strength and durability of 3D printed parts can often be lower than those made with traditional manufacturing methods. Quality control, speed, and post-processing requirements can also be challenging for 3D-printed parts.
Bio concrete based on bacteria is a technique that is still in the research and development stage but shows promise as a sustainable and low-cost alternative to traditional concrete manufacture and repair processes. Bio concrete uses naturally occurring and harmless microorganisms to form a dormant state within the material. Prometheus Materials is one company using this approach, it developed a technology that uses naturally occurring microalgae to produce a bio-cement that offers an affordable, strong, and durable alternative to carbon-intensive Portland cement.
Innovating the Concrete Production Process
Progressive start-ups and even tech behemoths are utilising artificial intelligence to optimise the process of creating concrete and cement to cut CO2 emissions such as Meta (Facebook’s parent company). The company has developed a new way of creating concrete that emits 40% fewer carbon emissions than standard mixtures.
To train an AI model to find the optimal recipe, Meta researchers used a resource that lists various properties of 1030 concrete mixtures called the Concrete Compressive Strength Data Set. This includes the strength of each concrete after curing for a week and a month and its carbon footprint. The AI could then analyse all possible concrete mixtures and find examples that matched a minimum given strength but also had the lowest possible emissions.
Berlin-based Alcemy is a developer of predictive analysis software designed to assist cement and concrete manufacturers. The company’s software offers precise quality predictions for mixtures and their ingredients before shipping products, enabling companies to counterbalance limestone and cement fluctuations. At the same time, Alcemy enables companies to produce more concrete using recycled ingredients precisely and safely. The company claims its software can save up to 50% CO2 during production.
There are also companies like Solidia and CarbonCure using concrete to store CO2. CarbonCure has developed a type of sustainable concrete that chemically converts CO2 into a mineral embedded in concrete. The technology is retrofitted into concrete plants and lets producers inject captured carbon dioxide into fresh concrete during mixing. The CO2 then gets converted into a mineral embedded in the concrete, providing climate benefits and increasing the concrete’s strength.
Time is Running Out to Develop and Commercialise Sustainable Concrete
The coming years will be crucial for concrete usage as demand shifts from established to emerging markets. Urbanisation in developing countries such as India and Indonesia will drive increased demand for concrete worldwide.
According to UN estimates, we will create another 230 billion m2 of floor area in the next 40 years, more than doubling the existing floor size of the world’s buildings. This comes as many concrete structures are nearing the end of their lifespans, resulting in a need for renewal and removal (a particularly acute problem in China) as buildings must be torn down and either replaced or abandoned.
Given these realities, there is an intensifying need to ramp up the development and commercialisation of environmentally friendly and sustainable concrete if we are to meet net zero emissions target.