Why do precast manufacturers use concrete sensors?
Table of Contents
Main challenges in precast establishments
Planning and optimisation in production
Currently precast establishments work to strict plans, schedules and templates in regards to their moulds, casting and striking. These schedules are driven primarily by the size and shape of the structure, along with the concrete strength within it. These factors will then drive the production programme and in turn the operations wider resources. Additionally, safety factors are considered and in turn add to the process length to ensure all casts are produced safely and without defect. This can include lengthier in-mould times during colder weather to mitigate cracking and fracturing during mould release. All of the above exacerbates production time and overall factory productivity.
Some factories optimise their production by relying on strike cubes and break tests, this is a tried and tested method however it is not without fault. The challenge with this method is the disparity between the concrete samples and the actual structure in question. Even when taking a sample from a cast structure and positioning it next to or on top of the structure to mimic its curing environment, the structure and sample will cure at varying rates due to their relative masses and internal temperatures. I.E. the larger the mass, the higher the internal temperature, the quicker the curing time, resulting in the desired strength being achieved earlier.
By monitoring the structure and not the sample, hours if not days can be saved on the production programme.
Terribly the construction industry has more fatalities than any other. Safety is paramount within the sector and rightfully so.
On one hand curing time wants to be as rapid as possible to allow for speedier production. On the other hand, this does not want to compromise the cast and safety, with early release potentially causing injury or worse. Not to mention waste of time, material and programme.
Remove the assumption and ‘fudge factor’ by having a clear insight within the cast.
Documentation and Quality Assurance
The rapid repeat nature of precast production, can contribute to confusion and queries from a QA perspective if and when an issue arises. Plus the added pressure put on staff to ensure reports and documentation keep up with production programme. Alleviate the pressure by leaning on technology to log and record all pours, temperatures and strengths, saved and backed up online for future documentation.
Could using concrete sensors help?
Two of the three main challenges explained above could be addressed if you knew the elements’ strengths. Imagine if you could see the concrete strength at any point in time. Then, you could start optimising production times and using your resources more efficiently while maintaining a high safety standards.
Five years ago, Contiga Tinglev, a group of precast sites owned by Heidelberg Cement, realised this was the key to increasing capacity and reducing product waste. So together with them, we developed Maturix Precast, a platform specifically designed to fit the needs and address the challenges of precast factories. They have been using it ever since with great success and with the below findings;
You can watch the video of multiple employees at Contiga explaining their experience with Maturix Precast below:
How does it solve the problem?
The Maturix system is a solution for intelligent temperature and strength monitoring in concrete. The system lets you see the real-time temperature and strength development from any device linked to a cast. This allows you to know exactly what is happening inside your concrete and how fast your concrete is curing.
The Maturix system comprises one or multiple sensors connected to transmitters, speaking to the cloud and feeding information into the Maturix Precast online platform. Sometimes, depending on cellular coverage you can add a supplementary Sigfox gateway to the system to improve your network coverage. See the whole system in the diagram below:
Using thermocouples cast directly in the structure, attached to the reinforcement and the other end connected to a transmitter, you can continuously measure the temperature inside the concrete. The collected data is sent wirelessly to the cloud platform, and the software automatically calculates the maturity and strength based on the timeline from casting, internal temperature and the designed concrete mix. You can then follow the strength development process via our online portal from anywhere, using a smartphone, tablet or PC, with an internet connection. Providing real-time insights into the actual curing status inside the structure.
How do you set it up?
The Maturix system offers a fast and simple installation once you set up the online platform and have a maturity calibration (only relevant for strength monitoring).
1. Set up your project in the online platform
2. Install the thermocouple
Secure the thermocouple with cable ties at the desired position where you want to follow the curing process.
3. Connect the transmitter
Plug the thermocouple into the wireless transmitter to start the continuous data transmission.
4. Pour the concrete
Cast the concrete. Start the monitoring in the software to follow the curing process in real-time.
5. Get the results
Access the data in the web portal from anywhere and stay updated with customisable alarms.
Benefits of using sensors
Using wireless concrete sensors as part of your daily production in precast elements gives a unique insight and added benefits;
Enable fast and secure formwork removal or post-tensioning work
Embedding wireless sensors in concrete allow you to monitor concrete temperature, concrete maturity, and concrete strength. Knowing the concrete strength in real-time (some systems also enable a prediction) lets you know exactly when your concrete element is ready to struck, freeing up the mould for the next pour. This allows you to speed up your production programme and increase overall company output.
Real-time data on dashboards in production
It may be hard and impractical to handle a phone or a laptop on the factory floor, with risk of damage or distraction. So why not display the dashboard and cast information from the Maturix system on a screen inside your production facility and offices, offering transparency to the whole team on cast development. The dashboard shows how far the curing is and how much curing time is left (prediction of the remaining curing). The risk of early formwork striking, resulting in waste is reduced while the product quality is enhanced.
Complement break tests with continuous real-time information
Concrete break tests are good indicators to see if you can obtain the final strength after the traditional 28-days; however, they are not really good indicators of the continuous strength development of the concrete in the form. Wireless sensors can fill the information gaps and provide an overview of the strength development process. You may still need to use a break-test to fulfil some specifications, but you can use the Maturix system to follow your castings along the way.
All data is automatically stored and formatted as reports in the Maturix Precast platform. These reports are ready to be exported, in PDF or other formats, and printed anytime. The reports are updated every 10 minutes when new data is received and include strength, temperature, and ambient humidity. This information can drive KPIs such as maximum temperature and production time. All data being collated in the background automatically for you, freeing up hands for other tasks.
Reduce heating costs
Heating the elements’ bed, either from underneath with hot water or steam or from the top with air or infrared heaters, is common place to speed up curing. Typically, these mechanisms use a standard daily “template” for when they need to be turned on and off. All of these methods use power to create heat, which is a huge cost especially in current times. However in a lot of cases these heating programmes will come on periodically even though a cast may have reached its desired strength and temperature. Maturix allows you to see precisely when you have reached the desired strength in real time so you can take action to optimise the heating usage. You may also discover that the elements reach strength much faster than you thought, meaning heating can be minimised or even turned off.
Detect issues earlier
By using concrete sensors daily, you will see common and expected trends in the data, meaning you will be able to see if there are sudden changes in the data. These could indicate a problem with some equipment or issues with the concrete mix. Usually, it can take weeks or months to identify hidden issues, such as a leaking heating pipe or abnormal water temperatures in tanks, but with continuous data, you can detect them faster.
Factories that use Maturix
Contiga, based in Tinglev, Denmark, is a precast factory with the largest total production capacity in one factory in the Nordic region, with more than 35,000 m² of production halls. They produce and deliver weekly 10,000 m² wall elements, 10,000 m² hollow slabs, 400-600 m beams, and 400-600 m columns, and they are driven by high-quality standards and thus strongly emphasize quality assurance.
Aarsleeff BIZ, based in Swinoujscie, Poland is a precast company from a different scale: They focus on extensive prefabricated concrete elements for the construction industry. Thus, they combine custom-made solutions with more standardized precast elements with high cycles. The factory produces middle or big-sized elements for international clients, combining speed, quality, and cost.