Achieving low-carbon concrete for more sustainable buildings often comes with a trade-off - slower early strength development, which can delay construction timelines and disrupt project planning. However, the EnviroMix® range from Chryso effectively eliminates this compromise, delivering a solution that supports both environmental goals and construction efficiency.
According to Patrick Flannigan, Chryso GM Technical and Product Support Management Africa, the drive towards more sustainable construction methods is gaining considerable momentum. “We are seeing growing demand from architects, designers and developers who are prioritising lower embodied carbon in their projects and are actively seeking innovative technologies to reduce the carbon footprint of new buildings,” he says.
One of the most effective strategies to date has been the use of supplementary cementitious materials (SCMs) in concrete mixes. These materials, which include fly ash and ground granulated blast furnace slag (GGBS), significantly reduce the proportion of ordinary Portland cement (OPC) required - and with it, the energy-intensive clinker content.
“This reduction is key to lowering emissions, but it comes with a drawback,” Flannigan explains. “Replacing OPC with SCMs has typically affected the rate of early strength development in concrete. This can delay the removal of formwork and scaffolding on construction sites or slow down the demoulding process in precast concrete manufacturing (PCM) environments, both of which are critical to maintaining construction timelines.”
This is where Chryso’s EnviroMix® range becomes an essential asset. “It offers a robust and reliable solution that ensures early strength targets are still met, even with higher SCM content,” says Flannigan. “This means contractors and precast producers can meet tight deadlines and keep production moving without compromising their sustainability goals.”
He notes that early strength development has a direct influence on project economics. “Any delay in achieving sufficient early strength can significantly affect a project’s financial viability,” Flannigan warns. “If formwork removal must be postponed, it can result in costly extensions to the construction schedule. This is particularly important because formwork and scaffolding make up a substantial portion of total concrete construction costs. The longer they remain in place, the more they cost in terms of rental, labour and project delays.”
This issue is equally critical in PCM environments. “In precast operations, fast mould turnaround is vital,” Flannigan explains. “Any delay in demoulding affects the production cycle and overall output, which in turn impacts profitability. EnviroMix supports the high efficiency demands of these operations by ensuring early strength is achieved even when using SCM-rich concrete.”
South Africa, he adds, has a long history of using SCMs in concrete due to its ready supply of key materials. “Pulverised fly ash from coal-fired power stations and granulated blast furnace slag from steel manufacturing have traditionally been readily available locally, encouraging the adoption of SCMs in the market,” says Flannigan.
“Chryso’s innovative technologies allow our customers to capitalise on these materials to lower the environmental impact of their concrete while maintaining critical performance parameters,” he continues. “Our EnvironMix range ensures early strength targets are met which simplifies project execution for contractors and improves production efficiency for precast manufacturers, making sustainable practices more accessible and less disruptive to daily operations.”
Looking globally, Flannigan highlights that European markets are leading the charge when it comes to embedding sustainability in construction regulations. “The EU has set ambitious goals - aiming for a further 30% reduction in carbon dioxide emissions from buildings by 2030,” he says. “To help meet these targets, many European countries are implementing legislation that imposes limits on the embodied carbon per square metre of construction, which is measured across the entire lifecycle of a structure.”
He believes it is only a matter of time before South Africa follows suit. “Given that many of our building specifications are modelled on or adapted from European standards, we expect similar regulations to be introduced locally,” he says. “There is a clear shift in the industry towards evaluating the environmental impact of buildings over their full lifecycle - from raw material extraction and construction through to operation and eventual decommissioning.”
Chryso’s contribution to decarbonising the global construction sector is already substantial. Its low-carbon concrete solutions, which include cement activators as well as advanced plasticisers and super-plasticisers, were independently verified to have prevented the emission of 15 million tonnes of carbon dioxide during 2023 alone. This figure reflects the widespread adoption of Chryso technologies across operations in 81 countries.
However, Flannigan cautions that successfully implementing SCMs is not simply a matter of substitution. “There is considerable variation in the chemical and physical properties of SCMs, particularly when it comes to fly ash and slag,” he says. “This variability can affect everything from workability and strength gain to setting times and durability. That’s why Chryso’s R&D teams and laboratories play a vital role - analysing the exact characteristics of each material before recommending the most effective formulation within the EnviroMix range.”
“Our team can design bespoke solutions based on the specific materials a customer is using, whether it is the type of fly ash, cement or other mix constituents,” Flannigan concludes.
The EnviroMix® range integrates tailored polymers and catalysers to optimise performance and enable up to a 50% reduction in carbon dioxide emissions per cubic metre of concrete. It is a powerful tool for the industry as it transitions toward a more sustainable future - without having to compromise on productivity or quality.
