Smart Concrete Maturity Monitoring in a precast factory
The extensive elements are used for…
CHALLENGES AT A PRECAST FACTORY
High demands towards the product quality as well as fast cycles for a great productivity are main challenges for a precast factory.
The curing process of precast elements is, compared to on-site casting, rather a controlled situation. However, good timing and efficient timing are even more important as lifting the elements and beginning of the next cycle on time offers high potential to improve productivity while ensuring excellent quality, leading to cost-efficient solutions.
For Aarsleff BIZ it is important to lift and move the element from the mould as soon as possible, to start the next cycle. The early strength development determines the optimal time to move the element, and monitoring at crucial positions as around the lifting hooks enables efficient and safe production without risking slippage.
For large projects it is common to require temperature and/or strength monitoring, either with test specimen or concrete maturity solutions.
Fryslan Offshore Wind Farm
Fryslan Offshore Wind Farm
- 89 external platforms
- 28 m3 of concrete per platform
- 43 MPa compressive strength required to lift
- Final strength C55/67
Demould the elements as fast as possible to reduce the cycle time while ensuring safety and high quality. Target: four platforms per week with required 43 MPa.
- Optimizing the demoulding time of large precast elements
- Shortening the cycles but reducing risk of damage
- Delivering temperature and/or strength documentation with minimal effort
- Test cubes do not 100% reflect the actual curing process in the structure and are a time-consuming and costly
Compression Tests VS. Concrete Monitoring
Compression tests with sample cubes or cylinders are the most common practice to gain insights into the concrete curing process. However, the standard method has limitations: “We were using sample cubes – but we knew the performance differs between cubes and the real element. We wanted to prove that we don’t have to wait just because the sample result says so” says Tomasz Dubrawski from Aarsleff BIZ.
Before using Maturix as a concrete maturity system, the strength needed to be proven by the average of three single compressive test results – Requiring a large number of the additional test specimens (6 to 9 specimens for each platform). However they are commonly used, Aarsleff BIZ knows about the deviation compared to the real strength development especially in large elements:
“Our main issue was, that with samples stored in laboratory conditions at 20°C, we achieved the required 43 MPa after four or five days. Having the temperature recordings from the element and samples we were aware of the temperature difference: We saw 23 – 27° in the lab, compared to 35 – 60° in the actual element, depending on the position. This has of course a huge influence on the strength!”
“We knew that performance differs between cubes and the real element – so measuring directly in the structure provides us with more reliable results. Also, the automatic documentation saves us a lot of time and effort!”
With using Maturix the Aarsleff BIZ team always knows exactly how the elements are curing and if they have to adjust the work schedule according to data. With the maturity system using the IoT network Sigfox, they have access to the data from anywhere. Alarms and automatic documentation ensure the quality control.
The precast factory could cut their cycles even in half during the summer – leading to higher productivity and being able to deliver elements even before the deadline.
Before using Maturix, the workers relied on their experience. With the maturity system, the production got more regulated and they gained confidence in lifting the elements on time.
Where possible, Aarsleff BIZ switched from using additional concrete samples to document the strength development to using Maturix – resulting in lower costs and less manual work.
About Aarsleff BIZ
Aarsleff BIZ is a precast factory in Poland and part of Per Aarsleff Holding A/S, the leading Danish contracting company. They produce big-sized prefabricated concrete elements for wind farms, bridges, harbours and many more. The large projects have extremely high standards and requirements, as the applications are demanding and they have to withstand extreme conditions, thus the product quality and documentation is beneficial.