The best wireless technology for concrete sensors
Smart concrete sensors can provide insights into the curing process boosting your efficiency on-site and optimizing the project management at any construction project. Several sensor solutions are available on the market and these offer numerous value-adding features. One of these features is the sensors’ ability to transmit the data wirelessly to your device or to the cloud. This allows you to see how your concrete pour is doing in real-time from your phone, tablet or computer.
The most commonly used wireless technologies for concrete sensors are Bluetooth, GSM and LPWAN networks. In this article, we explain what these technologies are, how they work and how they compare to each other.
Table of Contents
Bluetooth
Bluetooth was invented in 1989 with the goal of eliminating the need of using cables to connect devices that were nearby. With this technology, the data is transmitted between devices using short-range radio waves. These can send large amounts of data over short distances. The concrete sensors that use Bluetooth are usually all-in-one devices that run on internal batteries and are completely embedded in the concrete.
To collect the sensors’ data, you need to get within an 8 m range and wirelessly link to the transmitter with your smartphone. Once the devices are connected, you can access the data in the related app or software. Depending on the solution, you may be able to share the sensors’ data with other team members.
Advantages and disadvantages
The main advantage of Bluetooth is the internal memory, as the transmitter can store the data until you collect it. Moreover, it is possible to send large amounts of data at once.
The disadvantages are that for a good data transmission, the transmitter and your device may not be farther than 8 m from each other. This means that you or someone from your team needs to be on-site to collect the monitoring data. Moreover, objects such as large equipment, cranes, vehicles or concrete can affect the signal quality. For example, if the sensor is positioned too deep into the concrete the signal may be interrupted.
Another disadvantage is that Bluetooth requires a fair amount of power for every transmission which causes the transmitters’ battery to run out fairly quickly. The average battery life of these types of sensors is estimated to be around 3-4 months.
GSM
The Global Network of Mobile Communications (GSM) is a digital network used by mobile phone users around the world. When you are calling or sending an SMS from your phone you are probably using GSM. This technology uses cellular networks which are groups of antennas that collect the information that your phone is sending and transmit it to other devices. The concrete sensors that use this technology normally need to be placed on top of the concrete to assure a good transmission.
To use the GSM network, the concrete sensors must have a SIM card and a network provider. If the SIM card works correctly and the connection is good, the sensors will transmit the data directly to the cloud. This will allow you to see the data remotely in the app or software without the need of being on-site to collect it. Depending on the capabilities of the app and software, your team members, client and partners will also be able to access the data.
Advantages and disadvantages
The main advantage of using GSM is that it has antennas distributed around the globe providing great coverage almost anywhere. Moreover, its infrastructure is generally well maintained and supported.
Some of the disadvantages are that one SIM card per transmitter drives up the costs. Also, if the project is in a remote area where GSM does not have good coverage, it is not possible to use a gateway or manually set up an antenna to improve the network.
LPWAN networks
A Low-Power Wide-Area Network (LPWAN), is a type of wireless IoT network that can transmit small amounts of data wirelessly to the cloud using very low amounts of power. With this technology, the data is sent wirelessly by the transmitters through a gateway to the cloud. SIM cards are not required but you will need to make sure that there is network coverage in your project area. If the connection is poor, this can be extended by installing a small gateway at the project site.
With this technology, the sensors’ data is transmitted automatically to the cloud. So you can see how your concrete is curing remotely by opening the app or software from any of your devices. Depending on the solution used, it may be possible to share the data with other team members, clients and partners.
Advantages and disadvantages
The main advantage of LPWAN networks is that, if the right infrastructure is in place, they can transmit data over extensive distances. This possibility of long-range transmission makes the technology not only suitable for urban projects but also projects located in remote areas. Moreover, the data transmission consumes little power, ensuring a long battery life for numerous data transmissions.
The disadvantage of this technology is that the size of data that can be sent is more limited compared to the other two technologies. However, this is generally not a problem for concrete monitoring data, as the data size of the measurements is small.
Comparison
In the sections above, we have compared the different wireless technologies for concrete sensors as well as their advantages and disadvantages. In the table below, you can find a summary on the most important points mentioned:
Bluetooth | GSM | LPWAN | |
|---|---|---|---|
Location independency: Do I need to be on-site to collect the sensors’ data? | Yes | No | No |
Data collection: How can I collect the data? | Getting within an 8 m range and connecting to each sensor with your phone, tablet or computer | The data is sent automatically to the cloud | The data is sent automatically to the cloud |
Sensor position: Where can you place the sensor? | Around 3-5 cm (1, 18-2 inches) from the surface | On the surface | Anywhere |
Battery lifetime: How long will the sensors’ battery last? | Approx. 3-4 months* | Approx. 4 months* | Approx. 10-12 months* |
*The battery life values presented in the table have been determined based on the smart concrete sensors currently in the market. Note that the battery consumption might vary depending on the transmission intervals and the data size of those transmissions among other factors.
Why we choose an Iot network for Maturix
After considering cost, coverage and battery lifetime, we decided to use an IoT network called Sigfox, as this offered the most suitable features for smart concrete sensors. Both Bluetooth and GSM provide certain advantages, but these are not as suitable for battery-powered concrete sensors as IoT networks.
Bluetooth is a great technology for applications where wireless data transmission is required but the sender and the receiver are close such as wireless headphones, keyboards and hands-free sets in cars. And so is the GSM network, which advantages lie in the extensively established network for sending data with global coverage.
However, GSM has the drawback of driving up costs per sensor as each single one requires a SIM card. For Bluetooth, the limitation is that you may not be further away than 8 m (depending on the Bluetooth version used) from the sensor to connect and collect its data. Therefore, these types of devices do not offer truly remote data collection. Moreover, you cannot position the sensor freely in the structure as the sensor needs to be around 3-5 cm (1, 18-2 inches) from the surface to ensure good data transmission.
To sum up, IoT networks offer many advantages and are an ideal choice for concrete monitoring. These offer:
- Truly remote data collection with no need to be on-site
- Low battery consumption for extended device lifetime
- Free placement of the sensors at any favoured position
- No extra SIM card required in each sensor
- An established international IoT network with the option to enhance the signal with a gateway
Learn more about the Maturix solutions on the Temperature Monitoring and Strength and Maturity solution pages.
