The Converge Helix System streamlined tunnel construction in Victoria with real-time strength data, precise thermal monitoring, faster curing, and a 44% CO2 reduction using high cement replacement mixes.
Pouring concrete in tunnel construction involves navigating tight spaces, complicating equipment operation and worker movement. Maintaining precise temperature control is vital to prevent premature cracking and ensure that the concrete sets correctly and that the tunnel remains structurally sound and safe for use.
Spark used a 50% cement replacement mix for the ventilation shaft to substantially reduce the project’s eCO2. However, lower cement mixes typically increase cycle time, often adding significant cost, especially when poured in lower ambient temperatures. In Victoria, one of the coldest parts of Australia, typical temperatures are 5 - 14°C in the winter.
Standard concrete sensors would require repeaters throughout the tunnel, due to its length, curves and undulations. With space already tight, additional hardware, like repeaters, were not ideal.
Spark specified Converge’s Helix System due to its long-range (LoRa) connectivity capabilities and its extremely accurate, high precision thermal loggers. The Helix system complies with VicRoads specifications for thermal monitoring real time and trend understanding of concrete maximum temperature and temperature differential (used in early age thermal crack monitoring). Armed with real time strength data, Spark were able to continue concreting work as soon as concrete met strength, rather than wait for cylinder test results to return from the lab, mitigating the typically slower curing time expected from lower cement mixes.
Traditional concrete maturity monitoring requires waiting for lab results or following conservative estimates for concrete curing, which can lead to unnecessary downtime. With Helix’s real-time maturity data, Spark can eliminate idle periods, keeping the project moving forward more efficiently.
Thermal differential monitoring across the slabs is essential. Traditional data loggers can fail if someone trips over or cuts a cable, leading to non-conformance issues. The Helix system offers greater flexibility with more robust cables and nodes. The real-time data allows for immediate identification of problems, enabling quick fixes without losing valuable time to poor data collection.
Helix’s real-time data helps optimise the use of low cement mixes without sacrificing time efficiency. This allows NEL to maintain or even improve construction timelines while adhering to environmental goals.