IoT in Construction: Precise Management of Concrete Curing and Drying
As the Internet of Things shakes up the industrial world, organizations will soon realize the adage “innovate or die” is more than just a marketing ploy. Even in the construction sector which has been rather conservative in adopting new technologies, exciting IoT applications make the necessity for change increasingly evident. A great example is the management of concrete curing and drying.
Temperature and Humidity in Concrete Curing and Drying
Curing is the hardening process of concrete where desired properties are attained through the chemical reaction called hydration between water and cement. Curing determines concrete durability and service life and is thus among the most important activities in construction and flooring industries. Humidity and temperature play a critical role in this process, as they regulate the reaction and curing duration, thus directly impacting the final quality.
How long to keep it moist depends on the desired level of concrete strength. Excessive moisture loss can cause the hydration process to end too early, leading to inferior binding quality and weak concrete structure. Similarly, keeping favorable and uniform concrete temperature is vital to achieve the intended reaction rate and avoid thermal cracking. For exposed concrete, changes in weather conditions can also make the water freeze or evaporate before the process is finished.
Following curing is the drying stage in which concrete gains its final form for use. Here, relative humidity must be lower than 75 to 80 percent to make sure concrete dries out properly and circumvent mold growth. It often takes many months for both stages to take place.
Eliminate Second-Guessing with IoT
Understanding concrete temperature, relative humidity and strength gain alongside real-time ambient conditions is key to achieving optimal quality at the lowest production costs. Nevertheless, this has remained a significant challenge. Traditional practices are nowhere near ideal as they are expensive, time-consuming and sometimes, even destructive.
For example, to decide the curing duration, field technicians need to cast and send test specimens to labs for analysis, assuming that strength gain rates of later placed concrete will resemble the test. During curing, measurement of internal temperature and humidity requires drilling a hole into the newly poured concrete, risking structural damages. Needless to say, neither is reliable enough and operators fail to attain round-the-clock insights into ongoing processes. Due to the lack of visibility, operators often have to schedule extra time for curing and drying, which increases costs and lowers productivity.
We all know that IoT excels at collecting previously inaccessible data, and concrete monitoring is no exception. Instead of second-guessing what’s going on, smart embedded sensors now capture and deliver critical concrete data on a 24-hour basis, giving a full picture of the hydration process and strength development rates. In parallel, environmental sensors monitor important changes in ambient and weather parameters during curing and drying.
Real-time, actionable sensor data brings enormous opportunities to optimize concrete production and construction work such as:
- Accurate calculations of concrete maturity and real-time strength values to improve scheduling.
- Effective monitoring of both concrete core and surface temperature to avoid thermal cracking
- Timely reaction to adverse ambient conditions.
- Efficient use of mitigation instruments like HVAC systems or insulation materials.
- Better planning in installation of flooring products.
The Ideal Connectivity for Concrete Sensors
Battery-powered wireless sensors embedded directly into the concrete mass are the optimal choice for gathering concrete data. Attached to steel reinforcements right before the concrete is poured, these sensors are easy to install and require no cumbersome cabling or extra hardware. On the other hand, they impose critical connectivity requirements not to be overlooked: deep penetration capability for reliable data transmission through concrete and ultra-low power consumption to avoid battery replacement.
Bluetooth Low Energy is currently the most common solution, but it’s less than ideal. Due to the short range of BLE, field technicians have to walk around the placed concrete with an electronic device for data logging. On the other hand, Low Power Wide Area Networks (LPWAN) offer a viable option for automatic data collection, freeing up workers’ time for more important tasks. With a robust and scalable LPWAN solution, data from hundreds of concrete and environmental sensors across vast construction sites can be automatically captured at an on-site base station (i.e. data hub). It is then relayed to the preferred backend system and can be conveniently viewed from remote user interfaces.
As IoT applications and benefits start to manifest in the construction industry, scalable LPWAN connectivity enables easy and seamless integration of new sensors and devices into one unified communication infrastructure.