Low-Carbon Concrete
It’s pour day!!! After a long stretch of sunny weather, it’s drizzling the day we pour concrete 🌧. We’ve opted for a low-carbon mix supplied by Rempel Bros / Heidelberg - first time this has been spec’d for a residential project in North Van and a learning opportunity for all.
Concrete, and specifically cement - the binder in concrete, contributes huge amounts to global GHG emissions - up to 8% annually. The pressure is on the concrete industry to clean up manufacturing and mixes to drive this impact downward.
Low carbon concrete mixes typically reduce emissions through a combo of:
1) Higher recycled content or waste-derived aggregates
2) Low-carbon blended binders e.g.
- Portland-Limestone cement instead of Portland cement
- Supplementary cementitious materials (SCMs) like fly ash /slag
3) Fuel switching in the manufacturing plant (towards renewables)
4) Hyper-local material sourcing
Rempel’s 32 MPa Silver Superline mix offers a 50-70% carbon reduction vs 2017 Canadian ready-mix concrete baseline! The biggest challenge with low carbon concrete is that it can take longer to set and cure. The Silver mix takes 56 days to reach full strength vs 24 days (typical). That said, it still meets construction standards for loading within 7 days which our team can work with.
In BC, thanks to industry momentum, the concrete emission baseline has shifted downwards significantly in the last 5 years. The lowest carbon mix currently available is by Lafarge with a global warming potential (GWP) of 160 kgCO2/m3 for 32MPa. By comparison, Rempel comes in at 194 kgCO2/m3 and the 2022 BC Ready-mix average is 274-285 kgCO2/m3.
Given this, the carbon savings for Rempel’s silver product is more in the ~30% range vs BC baseline. Still significant! It’s sourced locally from their Mitchell Island Plant. Its impacts are reported transparently through an EPD (updated every 5 years). And we’re excited to be using this mix to help keep our project impact in check.
@twinlionscontracting @kpkg_customconstruction #netzero #netzerohome #lowcarbon #concrete #foundation #greenbuilding #sustainability
