Low-carbon concrete is painful for contractors. Here's a way out
High-SCM mixes decarbonize concrete but slow strength gain delays schedules and adds hidden cost. A liquid biochar admixture (ΔC) reaches higher decarbonization without impacting early strength or schedules.
alterBiota · July 21, 2026
Every producer and contractor faces the same request: lower the embodied carbon without lowering performance, blowing the schedule, or raising the price. The default answer, loading the mix with fly ash and slag, works on paper. On the jobsite, it often hurts.
The problem with leaning on SCMs
SCMs are a core lever in low-carbon mix design, and they aren't going away. But leaning on them alone comes at a cost to the people who place the concrete: slower strength gain keeps forms up longer, finishing slips, and the premium hides in the schedule and crews rather than the mix ticket. Supply is tightening, too. As coal plants retire, fly ash is harder to source and quality slag is regional.
Producers need an additional lever that doesn't depend on a shrinking supply chain.
The two mixes, side by side
Typical low-carbon mix
High SCMs (50%)
- 35–45% decarbonization potential
- Slow strength development delays schedule
- +10–20% hidden cost
ΔC mix
Moderate SCMs (30%) + 6% ΔC
- 45–50% decarbonization potential
- Faster strength development can accelerate the schedule
- Cost parity
The takeaway
ΔC delivers higher decarbonization than high-SCM mixes, without slowing early strength or the schedule — and can help accelerate it.
Why a liquid biochar admixture changes the math
ΔC is the world's first liquid biochar admixture. Instead of trading strength for carbon, it works with the mix you already run: it permanently stores biogenic carbon (30–50 kg CO₂e per m³), lets you cut cement through better particle packing, and doses like any other admixture with no plant retrofit and no specialty equipment. All environmental attributes stay with the producer and customer.
The effect compounds. For every kilogram of ΔC solids added:
1.5 kg
cement displaced
>2 kg
CO₂e stored
>20%
decarbonization on virtually any mix
At a 7% dose, that adds up to real, measured gains, the opposite of the usual carbon-for-performance trade-off:
9%
Less cement
26%
Lower GWP
10%
Higher strength
50 kg
CO₂e stored
per m³
It's qualified, and it's durable
Lower carbon only counts if the concrete still performs and passes spec. ΔC completed third-party testing to ASTM C494 Types A and F, exceeding all compliance targets. Independent RCPT testing at the University of Ottawa showed lower permeability across every binder system tested: 100% limestone cement, 25% fly ash, and 30% slag mixtures.
Proven in the field
This isn't a lab-only story. ΔC has gone into real production pours:
−22%
embodied carbon
Structural foundation
Silo foundation pour that met its 28-day strength target early.
~1 tonne CO₂e reduced
−13%
embodied carbon
Commercial apron
Curb and sidewalk placement on a commercial building.
Target strength exceeded
−22%
embodied carbon
Precast block
Segmental retaining-wall block production.
Cement reduced on the pour
See more field results in the case studies.
Where SCMs and ΔC fit together
None of this means abandoning SCMs. The strongest low-carbon mixes use moderate SCMs plus ΔC. The SCMs do part of the work, and ΔC adds biogenic storage and optional cement reduction on top, without dragging out the strength development or the schedule.
The point
If you're specifying or supplying low-carbon concrete and you're tired of paying for it in lost days, ΔC is the way out.
- See how ΔC works and dig into the full performance data.
- Model the GWP of your own mix with the ΔC estimator.
Tired of paying for low carbon in lost days?
Talk to us about a trial pour on your own mix design: samples, dosing, and how ΔC fits what you already run.