Why use expensive moisture meters when you can monitor concrete moisture levels using loggers installed in the concrete that measure conditions in real time and transmit the data to a cloud service?
Concrete Moisture Measurements Various types of remotely readable sensors and sensors installed directly in the concrete are generating a lot of interest on construction sites. And why wouldn’t they? From the construction site’s perspective, it would be fantastic if site personnel could read the moisture readings themselves on a laptop and anticipate and schedule material orders and coating work based on the results. Unfortunately, however, the reality is that remotely readable sensors installed within the concrete can provide a wealth of information, such as... concrete drying progress, but due to uncertainties regarding the results, coating cannot be initiated based solely on them. To support the final decision on coating, measurements must also be taken using the drill-hole or core sample method, which, when performed correctly, are currently the only accurate methods for measuring concrete moisture content.
The moisture content of the concrete must ultimately be measured using the core sample or drill hole method
Currently continuous monitoring of concrete moisture This can be done either using sensors installed in the concrete during the casting phase or using sensors installed in a drilled hole afterward. Sensors installed in drilled holes face the same challenges as traditional moisture measurement using the drilled-hole method.
Rapid temperature fluctuations can cause condensation inside the sensor tube if, for example, a balcony door is left open for a long time in freezing weather. The temperature difference between the concrete and the air above it causes a measurement error, as heat is conducted along the sensor wire in the borehole to the measuring head, distorting the temperature measurement and thus the relative humidity reading. In addition, sensors and transmitters installed in drill holes are easily crushed or otherwise damaged on the job site.
With sensors installed within the concrete, there is no risk of the sensor breaking. Furthermore, the impact of temperature fluctuations is reduced—though not entirely eliminated—since no part of the sensor protrudes above the concrete, preventing heat from being conducted to the measuring tip. A key advantage of sensors installed within the concrete is the ability to read measurement results even after the building is completed. If the sensors are strategically placed, the results can be read, for example, during an investigation into suspected water damage during operation.
Some of the challenges associated with sensors cast into concrete include calibration and ensuring the sensors are installed at the correct depth. Sensors embedded in concrete cannot be recalibrated after the fact, which means the accuracy of the measurement results deteriorates over time. For example, one manufacturer of widely used sensors installed in concrete castings offers a one-year calibration warranty for its products.
To ensure the accuracy of the measurement results, it is essential to install the sensors at the correct depth. For relative humidity measurements, In the RT guidelines Specified "evaluation depths" are used to compare measured moisture readings with the coating product’s threshold values when determining whether the surface is sufficiently dry for coating. The installation depths should be precisely known when ordering the sensors, and if anything changes along the way, even a deviation of a single centimeter in either direction can result in readings that are either significantly too wet or too dry. Therefore, the installation of the sensors should be left to a qualified moisture meter technician or another person familiar with the matter.
In addition to the above, it has not yet been possible to develop a sensor that can be installed inside the concrete mix and measure moisture with sufficient reliability to allow decisions regarding concrete finishing to be made solely on the basis of its results. Although loggers have advanced significantly in recent times, we still encounter situations where loggers installed in the concrete yield results that differ significantly from those obtained using the sample block method. Currently, the core sampling method is the most accurate method in use for measuring the relative moisture content of concrete, and manufacturers of sensors installed in the concrete pour recommend verifying the measurement results with core samples.
The expertise of a moisture meter is invaluable in determining the correct moisture content
Even if a moisture sensor that could be fully embedded in concrete were developed, I still don’t believe that construction sites would ever be able to do away with moisture meters entirely. Since the sensors are installed inside the concrete, they measure moisture only at that specific location. If you want to be sure that no damp areas are overlooked, you must at least scan all surfaces with a surface moisture meter and take core samples from areas where higher readings were detected.
In addition, the measurer is specifically an expert specializing in moisture measurement, which can assist the construction site in many ways that a sensor cannot: interpreting measurement results, assessing whether drying is proceeding effectively, identifying potential moisture risk areas, providing recommendations for measures to improve drying efficiency, assisting the moisture control coordinator in their work, etc. A remotely readable sensor is only capable of producing measurement results, the accuracy of which depends on sensor technology, installation, and measurement conditions.
Monitoring environmental conditions to aid concrete curing
Remote-readable loggers However, they are by no means completely useless when it comes to drying concrete. They are particularly effective and reliable for monitoring air humidity and temperature. This ensures that the air surrounding the concrete is sufficiently warm and dry, allowing the concrete to dry according to schedule. In most cases, delays in concrete drying are actually caused by inadequate indoor air conditions.
Without through environmental monitoring It measures the cause of concrete drying, not the result. This allows the concrete to dry even under tight deadlines and enables corrective action to be taken in a timely manner if conditions are not optimal for one reason or another. Our Environmental Monitoring Service This allows you to focus on what really matters when it comes to concrete curing.
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