Accurate aggregate moisture measurement has been the bane of producers since batch plant automation was invented. Despite all the benefits derived from modern automation we know without careful observation by the plant operators and/or truck drivers, produced concrete may or may not meet the end user requirements on the first try.
We are all too familiar with those consequences: lost time and material due to dry-up loads, rejected loads that are often a total loss, or customer complaints due to shrinkage cracking. There is, of course, the actions of the contractor that contribute to the final product performance. However, there is still a substantial amount of lost time and money during production when loads are too wet or too dry. Producers have made great strides in recording added water both at the plant and on the job to reduce their exposure. Nevertheless, I doubt a day goes by at most plants where more than a few loads must be touched up before leaving the yard.
It’s not for a lack of effort or expense. There are many quality vendors who provide aggregate moisture sensors in our industry. Together they have spent a king’s ransom on product development. For their part, producers have tried generation after generation of sensor offerings; some producers have success producing predictable slumps while others do not. This is despite the fact that the technology of modern sensors is very mature. Modern aggregate moisture sensors have microprocessors, proven sampling techniques, robust construction, and software algorithms that can be adjusted when needed. Yet as an industry, we are still far below widespread adoption. I maintain there are benefits to using aggregate moisture sensors. I think they are key for improving production, maintaining quality, and protecting companies at plants that are out of sight and out of mind. Yet I wonder — what as an industry are we to do to get better?
After some reflection, I believe the first thing we need to do is to remove the blindfolds. Let’s ask ourselves a few questions. How do we know if an aggregate moisture sensor is working? Is it even turned on? I have been surprised by how many sensors are turned off and the production managers don’t know it.
Your plant operators are a very valuable asset. They are responsible for ensuring the business process, that is the production cycle operates as best as they can make it. They’re not going to turn off an aggregate moisture sensor if it works. And they'd turn it off when it causes more trouble than the benefit.
Me included; we treat aggregate moisture sensors as a magic device. We put them into our plants and go on to the next thing. We may provide the operator(s) with some training on how to maintain it, we require moisture bakeouts to confirm calibration from time to time, but the entire process is still very opaque to the rest of the business, especially QC.
The results of the batch process, including the aggregate moisture data, is printed on the delivery ticket (and/or the electronic ticket) but generally speaking no one is monitoring the aggregate moisture sensors or asking if the measurements are even right beyond the plant operator.
This behavior is an artifact of how our business historically works. I mentioned ‘out of sight, out of mind’ earlier. Rather than treating aggregate moisture sensor performance as a "bolt on," it needs to be thought of as a mission-critical system that protects your bottom line.
Technology allows monitoring aggregate moisture sensor performance, along with operator water add, automatically and in real time. Just as there are dashboards that show the health of your other equipment producers should consider a smart dashboard for aggregate moisture sensors. Having a dashboard will provide moment by moment oversight of each sensor, aiding calibration, providing critical insight on a plant-by-plant basis, and provide automated alerts when performance is below expectations. Shining a light on the moisture measurement process will enable systematic management and data for the producers and vendors of sensors to improve the result.
Up Next: Managing moisture probe deployment in your company. Stay tuned!
As a key architect behind COMMANDbatch and REDI-VIEW, Randy Willaman brings decades of hands-on experience with batching systems. Through his blog posts, Randy shares his unparalleled expertise and insights with concrete producers looking to maximize their system's potential. Learn more about his services at willamansolutions.com.
