Østerport Station in Copenhagen contained several post-stressed floors to be used in the multi-story project. Every floor required the concrete to reach minimum strength development before tensioning.
Through the project, the contractor would validate that the concrete reached the required strength through crush tests, in which cast concrete cylinders are left onsite before being sent to test its compressive strength. Crush tests assume that the small concrete sample will have the same concrete strength as the mass concrete element, even though internal temperatures will be different based on volume of concrete poured will affect strength development. Even after getting proof that the cylinders have reached target strength, most contractors allow additional time to pass due to high costs associated with failure from tensioning before the concrete has reached strength.
SOLUTION:
Maturix™ Smart Concrete sensor technology was trialed to provide a better understanding of strength development, reduce time and eliminate risk. Maturix monitors the temperature of the placed concrete in real-time and calculates strength development based on the maturity curve of the mix design being used.
Type K thermocouple wires were fixed to the reinforcing steel in seven critical locations before concrete placement, and plugged into the reusable Maturix Transmitting Sensors.
Self-compacting C-35 concrete, containing an 80-20 ratio of rapid cement and fly ash was placed between 7:46 am and 11:23am. Temperatures were wirelessly sent every 10 minutes from the sensors to the Maturix cloud-based software, which then allowed the software to calculate strength in real time based on the maturity curve of the mix design.
One of the surprising results to the contractor was the difference in curing conditions across different sections of the floor. It was realized that, due to the positioning of a heater, some areas of the floor hit the required strength 18 hours before other areas. This would not have been observed without monitoring the concrete in real-time and highlights the importance of understanding what is happening with your concrete pour. At 6:28 am on the third day of curing, all seven sensors indicated they had reached the 20 MPa strength needed to post-tension. Knowing this allowed the construction team to post-tension one day earlier than expected and save one full day off the schedule, resulting in huge cost savings.
Since Maturix™ is wirelessly transmitted to a cloud-based platform, the data can be accessed from anywhere. No physical collection is needed, and alerts can be set up to notify individuals or entire teams as to when the concrete has reached the target strength.
In September 2019, Kryton added Maturix wireless technology to its Smart Concrete® product offering through a partial acquisition of Sensohive Technologies. Kryton will be an exclusive distributor of Maturix in North America. Contact us to learn more about the technology at sensors@kryton.com or +1.604.324.8280.
