Facing a commercial threat from precast rivals, Andrew Rovers and his team turned to an unlikely source – Scandinavian floor heating.
When Andrew Rovers MIEAust and his team at Civil Infrastructure Group (CIG) watched more project work shifting to precast concrete, they faced a commercial threat that demanded a technical response.
The answer they developed – a patented rapid heat-curing system called CIGcure – has since won them rail viaduct contracts across Victoria.
The company’s traditional approach to constructing large concrete piers required building columns, waiting for them to cure, stripping formwork, then constructing scaffolding to build crossheads on top. The whole process took about three weeks.
Rival companies were outbidding them for projects, using precast methods that reduced the process to roughly a week. This sped up delivery time and reduced disruption for road users, but also required enormous cranes – of 300-400 t – and elaborate site preparation.
Rovers saw an opportunity to pour columns and crossheads in a single operation – if he could just match the speed of precast projects using faster methods for curing onsite.
The challenge involved a fundamental rethink of concrete chemistry.
“You can’t just heat concrete up non-stop so it goes hard quickly, because you’ll actually damage it long term,” Rovers told create. “It damages the internal structure. So you have to be able to heat it and then cool it down. You can’t have any part of the concrete 20°C different from any other part.”
Testing and development
Searching for answers, Rovers discovered a Scandinavian company using water pipes within concrete slabs to ensure it would set in icy conditions. His team adapted the principle, developing a system using flexible tubing similar to hydronic floor heating, which was then connected to heat pumps that could both heat and cool.
The key innovation was algorithmic control. Sensors throughout the concrete member monitor temperature distribution. When the core becomes hotter than the outside, the system cools the interior while continuing to heat the exterior. Once temperatures equalise, the whole structure can be heated to specification limits, then uniformly cooled.
“We had a lot of sensors and computers that worked out when to start slowing down the heating on one part of the concrete compared to another one,” Rovers said. “Once it all got to the same temperature, we could heat it up to the absolute limit of the specification and then start cooling it down.”
The tubing remains embedded in the finished structure, eventually ground up during demolition to become part of the aggregate. The approach eliminates the need for massive cranes and elaborate site preparation, using only a 50-t crane compared to the 400-t equipment required for precast.
Development took about 15 months. The team tested on scaled blocks in their yard, replicating real-world dimensions as closely as possible. They applied for a provisional patent while still pricing jobs and convincing clients to trial the system – complicated by their inability to explain exactly how it worked.
“We were still pricing the job, and we’re trying to convince our clients to let us do the job, but we couldn’t tell them how we’re doing it,” Rovers recalled.
Proving compliance demanded extensive evidence. The team anticipated many tests but found themselves addressing concerns they hadn’t predicted – which they passed regardless, because the system operated within existing specifications.
“We did as many tests as we could come up with – then they had a couple that we hadn’t thought of. We actually met all the requirements of every test we did.”
Pushing through
The commercial impact exceeded expectations. From handover to completion, the team could finish a column and crosshead in about four days. During occupations with 24-hour access, they achieved a pace of essentially one pier per day.
“Any day you can save them is a massive saving,” said Rovers, who estimated client costs at roughly a million dollars daily on major projects.
Senior engineers have since identified additional benefits. Thermal stress during concrete curing typically requires 10-20 per cent of reinforcement in large structures. By controlling temperature distribution, the system may enable significant steel reduction.
“The reduction in steel is actually a [huge] number for the installation as well as the actual supply. And obviously, if you’re not installing steel, then there’s also all the carbon reduction,” Rovers said.
The company has discussed licensing with Snowy Hydro and concrete suppliers, balancing competitive advantage in Victoria against the impossibility of being everywhere at once. The latest generation of equipment uses heat pumps rather than separate heating and cooling units, doubling efficiency and halving generator requirements.
For Rovers, the experience validates persistence against scepticism. When colleagues and external consultants dismissed the concept, he and his partner pushed forward until results proved them right.
“We didn’t have support at all. But we persevered.”
WATCH: Precast and piling innovations in the New Bridgewater Bridge
Just over 20 years ago, TJH (Thiess – John Holland), on a site on Tramway Road, Morwell, Victoria (the old DiFabrizio steel fabrication site) made 1650 pre-stressed concrete bridge beams for the Eastlink Freeway in Melbourne that used heated water pumped through permanent, embedded pipes in those beams to greatly speed up curing of the concrete.
(This is from my own local knowledge, augmented by googling for the dates and numbers. I conducted crane inspections there as a mechanical engineer, and was given a tour that showed how the concrete curing process was being conducted).