We’re evolving cement and concrete to become a totally sustainable, net-zero material of choice, to help build a better future.
Concrete is ever-present in our daily lives and it has been integral to the development of modern society. It is used to build homes, skyscrapers, bridges, schools, hospitals, highways and dams and it has unlimited design possibilities. Some of the world’s most iconic structures—old and new alike—were formed with concrete.
The most consumed commodity on the planet after water, concrete continues to be essential to our progress and development, enabling our communities to be safer, stronger and more productive as we face increased urbanization along with the associated needs for transport, infrastructure and housing—all while contending with the growing challenges of climate change.
Today, our industry is accelerating its progress toward net-zero, advancing concrete’s role in helping mitigate climate change and build sustainably for future generations.
Concrete’s sustainability qualities
Reducing embodied carbon emissions is a priority for the cement and concrete industry. At the same time, energy efficiency, long service life and material efficiency over the full lifecycle of a structure are also essential factors in decarbonizing our built environment. And there’s good news in that regard. Concrete’s innate qualities – its strength, durability and resilience, its thermal performance, versatility, recyclability, its ability to uptake carbon and its local nature – offer significant sustainability benefits and help lower the environmental footprint of our buildings and infrastructure over their lifecycle.
Concrete makes our buildings more energy efficient, our roads more fuel-efficient and is 100% recyclable. It achieves all of these low-carbon advantages while maintaining its unparalleled design flexibility and performance, providing architects, designers and engineers enormous scope to meet project requirements in the most sustainable manner.
With operating energy demands representing over 90% of a building’s energy use and carbon emissions over its lifecycle, energy efficiency is critical.
Concrete’s ability to store energy helps moderate indoor temperatures, which in turn reduces energy demands from peak heating and cooling loads—all while making building occupants more comfortable.
Consequently, the strategic use of thermal mass, when integrated with smart design and geothermal technologies, can minimize the in-use energy demands of a structure over its service life by over 60%.
This is critically important to emerging strategies to electrify building operations, including heat, as part of broader efforts to decarbonize existing and new buildings.
Natural carbon uptake
Concrete absorbs carbon dioxide from the atmosphere, permanently capturing it in a process known as carbonation. A number of studies have shown that up to 25% of cement process emissions are reabsorbed and locked into concrete products over the course of their lifecycle, reducing the whole-life CO2 footprint of both cement and concrete.
So it’s clear, the environmental benefit of carbonation in concrete is an important consideration in measuring the carbon impact of building materials.
It’s also an important consideration in low-carbon design. Keeping concrete elements exposed increases carbon uptake and reduces greenhouse gas emissions and other environmental impacts associated with finishing materials like carpet and drywall.
Finally, exposed and crushed concrete usually associated with the demolishing or decommissioning of infrastructure and buildings increases the rate at which CO2 is absorbed from the atmosphere. Understandably, many experts believe that crushed concrete should be left exposed for as long as possible so that we can take full advantage of its ability to clean airborne carbon.
Concrete is renowned for its durability; concrete structures last for centuries and concrete pavements for decades, reducing the environmental impact of repair and replacement and slowing the circular economy loop.
Concrete has remarkable plasticity when freshly mixed, enabling designers to adapt it to whatever form, shape, surface, and texture they can imagine. Innovations like ultra-high-performance concrete (UHPC), photocatalytic concrete and pervious concrete are also enabling new and creative uses—and new ways to address a host of sustainability challenges.
Adaptability for future re-use
Because of concrete’s strength, sound-attenuation, and fire-resistant features, concrete buildings can easily be converted to other occupancy types during their service life. Reusing buildings in this way can help limit urban sprawl and reduce embodied carbon, further contributing to the conservation of our resources and preservation of the environment.
Totally inert when cured, concrete is literally emission-free and does not emit any gas, toxic compounds or volatile organic compounds, support healthy and safe indoor environments. Furthermore, its acoustic-attenuation qualities help amplify sound within a space or dampen it between spaces. So, concrete buildings can measurably reduce sound transmission between residential units, giving occupants more privacy and calm. Concrete can also provide attractive sound barriers to buffer sound along transportation corridors. This, too, makes it ideal for urban density.
100% reusable and recyclable
Concrete is 100% recyclable. It can also be repurposed and re-used over time, saving infrastructure resources, and minimizing energy, time and money spent on new construction.
Once it’s crushed, concrete can be repurposed as aggregate for use as sub-base material in roadbeds and parking lots, as riprap to protect shorelines or it can be re-used as granular material, thereby reducing the amount of material that is landfilled and the need for virgin raw materials in new construction. And much more can be done yet to recycle concrete back into new structural products to further reduce the need to raw materials and better support the transition to a circular economy.
Through its educational work with specifiers, the Canadian cement and concrete industry is working to increase awareness of the benefits of using recycled concrete instead of virgin aggregates and promote attending best practices.
Concrete is local
The supply of concrete is typically no more than an hour away from a job site, avoiding emissions that come with shipping building materials over long distances and delays that halt progress at the construction site.
A more sustainable built environment
Our industry is moving from grey to green, working to ensure that cement and concrete continue to evolve to become a totally sustainable, net-zero material of choice to help build a better future.
We continue to advance concrete products to anticipate the changing needs of construction and bolster the circular economy. Take for example 3-D concrete printing, which helps reduce construction waste, shorten construction timeframes and enhance design flexibility. Or electro-conductive concrete, which amplifies the energy efficiency benefits of concrete’s thermal mass for buildings and, when used in outdoor applications, helps reduce the use of de-icing products like salt that are harmful to the environment. Research is also underway about the role that concrete can play in energy storage, potentially transforming our buildings into giant batteries to support our transition to solar, wind and other renewable energy sources.
Lowering emissions in buildings and urban environments
Concrete’s thermal mass performance supports grid stability, reduces emissions from energy use, generates energy cost-savings and improves the passive survivability of buildings when power or heating fuel services are lost.
Concrete also makes urban areas cooler as its lighter color reflects more sunlight than other, darker materials.
Because of its durability, concrete structures are repaired and replaced less often, which reduces overall carbon release.
Another key factor is that concrete absorbs CO2 from the ambient air over time, returning a portion of emissions from the cement manufacturing process to the building itself.
Sustaining transportation networks
The roadways, public-transit systems, bridges and airstrips that connect us are integral to our communities and daily lives.
Concrete pavement is a durable, economical and sustainable solution for not only these essential components of our transportation infrastructure but also for our bus lanes, heavy traffic intersections, parking lots and sidewalks. Concrete pavement:
- Improves fuel efficiency of vehicles by up to 7% when compared to other pavements.
- Is lasting, with an average service life of 30-50 years.
- Is less susceptible to damage from heavy vehicles and requires little maintenance throughout its service life.
- Does not require lengthy lane closures during repairs, with roads able to reopen within as little as six hours after work completion, reducing time-in-traffic auto emissions.
- Has demonstrated environmental benefits like reflecting much of the sun’s heat, keeping cities cooler, reducing the need for air conditioning and lowering smog ratings. And it’s recyclable.
Maximizing economic value
Thanks to its durability, resilience, low maintenance requirements and energy efficiency, concrete structures reduce costs related to operational energy consumption, maintenance, and rebuilding.
Concrete can be recycled, re-purposed and re-used over time saving infrastructure resources and minimizing energy, time and money spent on new construction.
Concrete lasts longer and costs owners less in maintenance and repairs over the lifetime of a building. And insurance costs are significantly lower than for buildings built with combustible, moisture-sensitive materials.
Design strategies to reduce concrete’s foorprint
The most sustainable, low-carbon building is often the one already built. Refurbishing and retrofitting existing structures to improve energy efficiency is usually the best option for avoiding and reducing carbon emissions from the built environment.
However, when new construction is required, there are main strategies that architects and engineers can combine to optimize the concrete mix design to reduce the project’s carbon footprint. They include:
Encouraging their concrete producer to use lower-carbon cement, like Portland-limestone Cement. This immediately cuts the concrete’s embodied carbon footprint by up to 10% compared to traditional cement, while ensuring the same durability and resilience. It is a simple solution—at no additional cost.
Optimizing the use of supplementary cementitious materials (SCMs). Commonly used today, SCMs can easily replace 30% or more of the cement required to produce concrete, thus reducing GHG emissions while delivering all the advantages of regular concrete and applying a circular-economy approach to waste.
Using admixtures. Most concrete uses some sort of admixture, generally to improve performance and efficiency by making concrete more workable, economical, etc. Because they have an extremely low-carbon footprint and represent only 1% or less of the total concrete material, they can also dramatically improve concrete’s performance and significantly reduce its environmental footprint.
Leveraging concrete’s CO2 uptake properties
Concrete’s ability to permanently capture CO2 in a process known as carbonation, is among its least well-known advantages. Yet, recent research show that concrete can uptake more than 25% of the CO2 emitted during its manufacturing process.
Architects and engineers can also maximize CO2 uptake by specifying the use of exposed concrete wherever possible or by using one of several commercially viable technologies that accelerate carbonation.
Optimizing concrete volume
Today, experts agree, good design practices should always include measures like optimizing the total amount of concrete used for a given structural element. For example, in buildings, there may be opportunities to incorporate a voided product like hollow-core for floor slabs, or the use of high-strength concrete to reduce the size or increase the spacing of columns to maximize rentable space. Whatever the project, the key is always to analyze each element and optimize the concrete mix and volume to match, maximizing efficiency and minimizing carbon intensity.