How Automatic Moisture Probes Impact the Bottom Line of a Concrete Producer's Operation

January 2, 2024

Every producer knows that achieving consistency keeps the operation predictable, and reduces time, waste, and cost per load of concrete delivered. Thankfully, the critical factors that affect the quality and consistency of each load are controllable at the concrete batch plant. Moisture control is one of these critical factors, impacting areas like yielding, strength, set times, and finish.

It is very important to maintain regular sampling of material stockpiles for long-term data; however, this method can fall short as a primary moisture control method through your COMMANDbatch system. The purpose of stockpile sampling is for gathering many data points over time to then be aggregated for a general picture of the properties of large quantities of material, be it from an on-site rock plant, or delivery. There are multiple factors such as ambient moisture and weather, stockpile wetting via sprinklers, and changing material source (impacts absorption) that will always be changing.

The challenge for producers is mitigating these changing factors in real time, for each load of concrete. Operators have many important roles, and keeping track of material moisture can reduce time needed for more critical duties. This is where automatic moisture control probes provide their benefit. Located directly in the most readily available material source for the batch plant (the aggregate storage bins), these probes monitor the moisture of the material in real time, and can adjust the load water as the material flows over the probe in the bin. This allows for consistency in slump predictability, improved yielding, and overall greater efficiency.

Inaccurate moistures lead to inaccurate compensations in the concrete that alter the properties of the mix. Consider the following example:
A mix design calls for 1800lbs of sand. A moisture input of 5% means there is 95lbs of water (over 10 gallons) in the sand. This water is accounted for by a combination of adding more sand, and holding back water from the load.

The moisture compensation will also change the quantity of the material added to the mix. Too much sand added to compensate for a high moisture reading creates a more dense mix leading to potential hydration issues in the concrete slab, and will also hold back extra water from the mix.

1800lbs / (1-.95) = 1895lbs | 1895lbs - 1800lbs = 95 lbs. of water in the sand.
Typically the system will then add 95 lbs. of sand, and hold back water until slump is checked at 90 revolutions to achieve prescribed mix design quantities.

But the additional 95 lbs. of sand is also at 5% moisture...
95lbs / (1-.95) = 100lbs | 100lbs - 95lbs = 5 lbs. of water in the added sand.
Though a minor amount, the compounding effect of this compensation becomes complicated and time consuming.

It is clear to see how automating this input in real time can improve consistency and quality over time. In addition, reducing driver's time spent adjusting slump, operator's time spent monitoring moistures, and quality control's time chasing mix design targets could greatly improve the overall operation's profitability.