One of Australia’s largest road infrastructure project BrisConnections, involved $4.8 billion Airport Link, Northern Busway (Windsor to Kedron) and Airport Roundabout Upgrade projects, comprising three, linked, road infrastructure projects:
• 6.7km Airport Link toll road (more than 11km of tunnel and ramps)
• Windsor to Kedron section of the Northern Busway (1.5km tunnel)
• 750m flyover bridge and fast-diamond intersection replacing the airport roundabout.
BrisConnections contracted Thiess John Holland, a joint venture between Thiess Pty Ltd and John Holland Group, to undertake the design and construction of Airport Link, Northern Busway (Windsor to Kedron) and Airport Roundabout Upgrade.
Thiess John Holland engineers approached Pyrosales to deliver a temperature monitoring and data logging solution to satisfy the Concrete Curing Specification developed for the project.
The Concrete Curing Specification for Thick Concrete Sections applied to any slab 1.8 meters thick or greater. The data monitoring equipment supplied required both visible temperature monitoring for engineers supervising the work, and logged temperature data to provide reports for the project approval process.
The curing temperature had to be monitored at two points at approximately 3m centres, one 50mm below the slab surface and another at the centre of the slab directly below the surface installed temperature element. Depending on the concrete type, the maximum allowable temperature of the curing concrete was between 70-80°C. The maximum allowable temperature differential between the two measurement points was either 20 or 28°C depending on the aggregate used.
Structural Slabs up to two meters thick were poured onto open excavated ground on top of pile driven piers to form the entry and exit tunnel approaches for the project.
Structural Supports were also poured for the Airport Roundabout Bridge Flyover and had to comply with the Concrete Curing Specification.
Supply cost was an important consideration due to the number of sites involved at the same time.
The concrete pouring sites extended across the entire length of the project in five separate locations.
- All locations were open ground with no cover.
- The sites were constantly traversed by heavy road and tunnel construction equipment. Damage to the data logging equipment was a substantial risk.
- Installation of the temperature sensors had to occur during the building of the steel reinforcing grid for each concrete pour. Each element was sacrificial, remaining in the cured concrete.
- There were multiple sites being poured at the same time.
- The data logging equipment had to be located at a distance from the pour that would not inhibit the construction process.
- All temperature monitoring equipment had to be moveable as the pouring progressed along the site locations.
- The curing temperature data had to be logged for seven days after each pour.
After several discussions with the client about possible systems that would meet the requirement, Pyrosales supplied the following items:
Temperature Elements and Extension Cable
The elements consisted of a matched resistance thermistor bulb in a waterproof housing and 16 meters of extension cable. Pyrosales maintained stock of the components in ourBrisbanefactory to enable fast production of the elements and security of supply to match the requirements of the project. The cost was reduced through production runs to best utilise the labour input required.
Dual input Data Loggers
These units met the criteria of the application in the following ways:
- Dust and water tight
- Robust polycarbonate case
- IEC standard 60529
- Dual input to monitor the two measurement points required
- Clip mounted and lockable for easy relocation and security during the 7 day logging period
- LCD Display
- Low battery warning
- Logging indicator
- Visual alarm
- Display alternates between the two channels
- 10,600 logs per channel
- Low Cost per Unit
The dual input and alternate display of the two temperature points enabled the onsite engineers to closely monitor the relative curing temperatures, so that corrective action could be taken if variations were outside the allowable limit.
Logged data could be downloaded on site while the units still operated or the unit could be removed at the end of the logging period for downloading at the site office.
The software program provided delivered an outstanding range of features and facilities for operating the data loggers, and for designing and printing the graphs. The graph produced clearly showed the relationship of the two temperature points for later reporting. The data could also be exported to Excel for other investigations.
Pyrosales’ ability to provide a total solution, and our innovative approach to the problems, allowed us to provide a package that not only met the needs of the client but was compact, transportable and cost-effective. Engineering management reported being very pleased with the solution that operated without problems and delivered all the data required to meet the criteria of the Concrete Curing Specification.