Decarbonizing Concrete: Roadmap to an Absolute Zero Carbon Future

If concrete were a country, it would be the third highest in climate emissions globally -- that’s how pervasive concrete is as a source of carbon emissions. Large amounts of carbon are emitted in the breaking up of limestone to make cement (a process known as calcination) and the heading up of cement kilns to very high temperatures. At Lendlease, we see not only the problem, but also the opportunity with concrete. 

At Lendlease we believe the only way to take on big challenges is to take them on directly. We’ve set the industry leading target of Absolute Zero carbon across all scopes of emissions by 2040, including those related to construction materials like concrete. To meet this target, we’re taking action across a number of fronts, via pilots to reduce the amount of concrete we use and to decarbonize it where possible. 

Low-Carbon Concrete Project Pilots  

On development projects, where we oversee design and construction, we are working with our structural engineers to reduce the amount of overall concrete designed into our structures. For these projects, we require our concrete providers to give us environmental information before we award contracts to ensure that we are getting both the best carbon performance that our suppliers can meet our cost plan.

We are also pushing beyond the typical way companies decarbonize concrete by replacing percentages of the cement in concrete with industrial byproducts such as slag and fly ash. Cement is the highest carbon-emitting component of concrete, so tackling cement emissions is critically important. Unfortunately, supplies of slag and fly ash are dwindling globally. Further, the US currently only makes about 79% of the cement it uses, so there is clearly a need for low-carbon, domestically produced cement to replace the traditional cements we use in concrete.

We are also working with new concrete mixes. On our 1 Java project in Brooklyn, we replaced 40% of the cement in the foundation with a recycled glass product called ground glass pozzolan at no added cost to the project. We worked with our concrete subcontractor and batch plant to procure, batch, and pour foundation concrete with Pozzotive, a ground glass pozzolan product made in the greater New York City region. In New York, we are also deploying maturity sensors to tell us when a concrete pour comes to strength to reduce the use of unnecessary fuels to heat concrete beyond what’s needed. Many contractors would be happy with a 40% reduction on the project level, but it doesn’t get us to our goal. We need to go further. 

Decarbonized Concrete Industry  

Late-stage concrete startups in the US are creating competitive products to decarbonize concrete, and Lendlease is evaluating these materials. We are partnering with ClimateWorks, which provides us with expert consulting, to execute additional demonstration projects on the East and West coasts this year with additional innovative concrete products. As these products scale, we will be ready to use them as our clients demand more decarbonization. 

Happily, Lendlease is in good company with our efforts. Many of the biggest buyers of concrete in the US are attempting to solve the same problem and collaboration across the market will accelerate a simple yet ambitious goal: making zero-carbon concrete ubiquitously available in America.

To get these companies to scale, we must prime the pump. These innovative yet proven concrete technologies have a short-term premium, and with cost concerns and no way to predict precise future demand volumes, the forward contracts these companies need to unlock project financing are difficult to execute. The companies need this capital to spin up their production processes to get to market rate, which we think can occur within the next 2-10 years, depending on the specific concrete alternative product.

We are working in coordination with other buyers of concrete to send a strong demand signal, such as spurring the collective use of performance-based specifications to try to help these companies get the financing they need to get to scale. Our hope is that a collective demonstrated demand can help these companies connect with the entities that can invest in that temporary price premium. That will enable the companies to reach the scale they need to fundamentally change how concrete is made in the US in the next ten years and enable us to meet our ambitious mission zero targets.

Future Outlook  

We believe in a world where we use concrete to build the homes and hospitals we need without risking the health of our planet. Our customers, investors, and countless project stakeholders have joined our mission to absolute zero. But we can’t operate in isolation. It will take the work of countless construction companies, architects, structural engineers, investors, architects, developers, cement manufacturers, batch processors, and more to transform how concrete is made in the US. Please join us on our path to absolute zero.