The use of IoT sensors in construction job sites was tested by one of the leading construction inspection authorities, Vahanen Group Oy, to confirm that using IoT sensors for concrete slab RH/T monitoring meets the industry requirements.

Using IoT concrete sensors for concrete slab humidity measurement has emerged as the latest new technology tool in the construction industry. In the past, the concrete RH measurements have required job site visits, one measurement at a time, over several weeks and months during the concrete drying time. Unlike this traditional spot-check method, wireless IoT sensors can be left behind to monitor concrete slab and environment continuously, enabling real-time analytics of the measurement data. For example, predictive algorithms can be then used in estimating the time it takes for the concrete slab to dry to the target humidity level. The real-time data also provides actionable feedback and alerts to job site managers for controlling the environment for optimal drying conditions and securing on-time project scheduling.

Vahanen Group’s ( team of construction experts performed validation testing by using eGate as an example of IoT sensor technology. The purpose of the test was to provide the industry with much-needed information about the actual performance of commercially available IoT concrete sensors when used for continuous monitoring over extended periods.

eGate NSENS concrete IoT sensor was selected for the test setup, with its wireless data-streaming connection to the cloud analytics platform. Four eGate sensors were installed at two separate job sites for 1- and 2-month data collection periods. Installation was done in accordance with the Finnish RT 103333 construction guide, equivalent to the ASTM F2170 standard. eGate NSENS sensor is specified with +/-0.8%RH accuracy within 0…50C temperature range.

At the end of the eGate sensors measurement period, reference sensors were installed in concrete next to the eGate sensors, for accuracy and stability comparison. Vaisala HMP40S, with a recent calibration certificate, was selected as the reference standard. Vaisala HMP40S is a traditional (wired / non-IoT) RT-103333/ASTM2170 compliant sensor probe, with a specified accuracy of +/-1.5%RH over the RH range, when calibrated also at 95%RH high humidity point.

Vahanen Group’s Unit Manager, Mr. Sami Niemi, explains the test report findings: “According to this performance test, using eGate NSENS IoT concrete sensors, we have demonstrated that there are now commercially available IoT RH/T sensors on the market that meet the RT-103333(ASTM 2170) requirements (+/-2%RH). Also, the results show that eGate NSENS sensors did not get stuck at the 100%RH reading after being exposed to high humidity water saturation at the beginning of the measurement, which has been the problem with many other similar sensors in the past.”