Concrete shapes our world—it’s in our homes, our roads, our hydroelectric dams, our cities. Its durability and relatively low cost have made it the backbone of modern development. The problem is that producing concrete, and more specifically cement, generates a significant amount of greenhouse gas emissions.
At a time when the construction industry must rapidly reduce its carbon footprint, the desire to rise above mere convenience and find tangible solutions has become a necessity.
And many alternatives now exist, from cement substitutes and new types of concrete to engineered wood, bio-based materials, and recycling!
Why Is Concrete so Damaging to the Environment?
Cement manufacturing (concrete’s main binder) makes up a significant part of global CO₂ emissions: around 8% of total human-generated emissions.
Most of the emissions linked to concrete arise from two main processes.
- First, the chemical reaction: turning calcium carbonate into lime releases CO₂, regardless of the energy source used.
- Next, fossil fuels are burned to reach the ~1,450 °C needed to fire clinker (a hard, nodule-shaped material essential for cement production). Thus, a substantial share of a concrete mix’s carbon footprint stems from the amount of cement it contains.
This is all very technical! Put simply, decreasing the amount of clinker means less CO₂.
“Concrete” Technical Alternatives
Reducing concrete’s environmental impact doesn’t mean we have to stop building. Above all, it’s a call to rethink the way we manufacture concrete and what materials we use. Here are some applicable solutions.
1. Less Cement (the Simplest Solution)
As mentioned earlier, cement is concrete’s most polluting component. The good news is that we can use less of it without compromising strength.
How? By replacing part of the cement with other existing materials, such as
- power station waste;
- metallurgical by-products;
- certain processed clays.
The result:
- up to 30% fewer CO₂ emissions
- a concrete still sturdy enough for several residential applications
- a solution already implemented in Québec
In short: same concrete but greener recipe.
2. New Generation Concrete (Geopolymer Concrete)
This material goes one step further: a whole new type of concrete mix with very little (or no) traditional cement.
The advantages:
- a much lower carbon footprint
- industrial waste recycling
The drawbacks:
- more expensive
- relatively unknown among builders
- still uncommon in residential construction
It shows promise but is not yet the norm for homes.
3. Solid Wood: the True Substitute
For certain components like the floors, load-bearing walls, and frame, engineered wood can serve as a substitute residential building material instead of concrete.
Why it’s an interesting alternative:
- Wood stores carbon instead of releasing it.
- Québec produces it locally.
- Its environmental impact is often lower.
But keep in mind:
- Humidity is an issue.
- The building must meet fire safety standards.
- Wood’s durability varies according to its use.
It’s an increasingly popular option, especially for modern and eco-friendly buildings.
4. Bio-Sourced Materials to Insulate Differently (Like Hemp)
While it can’t be used as part of a dwelling’s load-bearing shell (it’s structural components), hempcrete (a mix of hemp and lime) excels at
- insulation; and
- humidity control.
The advantages:
- a very low environmental impact
- increased indoor comfort
5. Recycled Concrete (Effective and Logical)
Instead of sending concrete rubble to the landfill,
- it’s crushed up; and
- reused in foundations, roads, and as backfill.
The advantages:
- less gravel extraction
- less waste
To conclude, although not the primary cause of environmental degradation, concrete must evolve for the sake of our planet. As a homeowner, you have the power to effect real change, especially by choosing a building contractor who uses more eco-friendly techniques.
