A bespoke cooling solution from Coates helped the S2M Evolution Alliance cure concrete more efficiently during a major infrastructure project.
When the S2M Evolution Alliance adopted an innovative bridge construction method during Phase 2 of the Stephenson Avenue Extension in Perth, it faced unique concrete challenges.
“To limit the impact of bridge construction on commuters, the Alliance was required to launch, slide and lower pre-formed, reinforced concrete segments over the freeway and train line in live traffic conditions,” said Matt Baston, Launch Manager - Structures, for S2M Evolution Alliance. “This was the first use of this construction method for a bridge in Perth. To achieve this, there were a number of unique concrete challenges to overcome.”
Working with high-strength S60 grade concrete, the Alliance needed to perform a large number of high‑volume in‑situ concrete pours, and to quickly and consistently cure the 1.8m-thick bridge segments. To ensure the strength and integrity of the bridge structures, concrete temperature had to remain below 70°C, with a differential of less than 20°C.
Coates was engaged to design and implement a bespoke concrete cooling system to help meet these requirements.
“Concrete with a high cement content produces substantial heat, which made working with the specified S60 concrete and managing temperature as it cooled particularly challenging,” explained Shane Lee, Power & HVAC Solutions Specialist at Coates. “The Alliance needed an effective cooling system to meet the project requirements, ensuring the concrete cured evenly, preventing cracking and achieving the large concrete spans.”
Matt added: ““We chose Coates to support this project for the breadth of experience they bring and their reputation for developing innovative solutions to complex problems. We also valued their willingness to lend time and expertise talking through technical challenges.”
Coates worked closely with the customer to design a solution that carefully controlled the concrete temperature by pumping chilled water through polyurethane pipes installed in each concrete segment, allowing the concrete to cure more rapidly and evenly.
The system featured two 200kW chillers set to run at 8°C and two plate heat exchangers, along with pumps and buffer tanks to draw water through the bridge segments and plate heat exchangers.
“Having a closed loop on the chiller was key to the efficiency of this design,” Matt said. “Adding a plate heat exchanger also minimised the impact of high return temperatures and improved the efficiency of cooling incoming fluid.”
To achieve maximum heat transfer, water had to be pumped through the cooling system at a precise temperature and flow rate. Coates’ engineers worked closely with the Alliance to determine this approach.
“A combination of factors controls how quickly heat escapes from the concrete, including the concrete grade and the thermal density of the polypipe in each segment. We used detailed modelling and calculations to achieve the right water temperature and to determine the speed at which it must flow through the system,” Matt said.
“With additional input and expertise from Coates, we could trust these calculations to make informed decisions on the design of the cooling system and the equipment we needed to implement it.”
Coates’ cooling solution, coupled with careful placement temperatures at night, resulted in compliant concrete pours. It helped the Alliance to achieve a 10% reduction in concrete curing time, which also had a positive impact on the launch schedule for each bridge segment. “By the time the second pour was complete, the time saving had already offset the cost of hiring the system,” Shane said.
Matt describes Coates’ cooling system as critical to meeting the project requirement. “Even if temperature wasn’t a factor, this system still delivers considerable value to any project that requires a large volume of concrete to be quickly, safely and consistently cured,” he said.
Contact Coates to discover how its equipment and specialist solutions can support the delivery of your next major project