The rugged, hard-wearing microwave Mixer Moisture Sensor

With AquaMix microwave mixer moisture sensor and suitable controller, you can control the water dosing to give consistent moisture or slump in the final product.
The control system for sensing water in the mixer and adding the right amount.
Aquamix specification
AquaSense 2280D uses a Windows Graphic User Interface (GUI) for setup and moisture calibration. Here’s how it works:
Hardware for use with AquaSense and AquaMix.
Can I take a sensor calibrated for sand and use it on other materials? Can I use AquaSense 2280D’s sampling feature for on-the-fly batch correction? Which is the best output choice, 0-10 volts or 4-20 mA? This page answers your Moisture, Frequently Asked Questions and others.
AquaMix microwave mixer moisture sensor with its mounting flange

The AquaMix 2270D digital microwave on-line concrete mixer moisture sensor is highly sensitive to moisture changes in the mixer.  Installed in the concrete mixer floor or wall, it measures the material as it is mixed.  The ever-changing moisture value connects to the control system for measurement and concrete moisture control.  The high-tech Silicon Nitride ceramic used for the AquaMix sensor’s faceplate is almost diamond hard; thicker and tougher  than anything else in the industry.  As a result, it endures the harsh abrasion of the aggregates as they mix.  See all moisture sensor models.

Product features

AquaMix mixer moisture sensor with its adjustable jackscrew assembly
AquaSense 2280D corrects the dry weights of material in the batch.  AquaMix 2270D corrects the water in the mixer to give constant yield, colour/texture and workability, as well as strength and durability . . . . Read more
  • Faceplate lasts for the life of the mixer moisture sensor.  This is many years, even with the most abrasive aggregates, making it the toughest in the industry as a result.
  • Stainless steel body gives long wear free life.
  • Mount allows adjustment as the mixer floor wears.
  • Internal software uses Dynamic Calibration to allows older readings to be re-used or discarded.
  • Internal storage of all calibration results makes each sensor independent of external software.
  • Windows Graphic User Interface makes setup and calibration fast and easy.
  • Industry standard digital interface, compatible with all control systems.
  • Call us about a trial in your plant.

Faceplates and wear

Silicon Nitride cap, at left, shows no wear while Alumina at right is at end of life
Most manufacturers of microwave mixer moisture sensors use a ceramic known as alumina, which is aluminum oxide, Al2O3.  This material is very hard and tough, lasting months to years in concrete mixer applications.  The actual lifetime depends on the volume of concrete produced and the abrasive qualities of the aggregates.  One major manufacturer has switched to sialon, an aluminum oxide / silicon nitride composite giving wear superior to alumina.  In 2002 we investigated sialon and silicon nitride, settling on silicon nitride, Si3N4 for all future production.  This material is harder than both alumina and sialon . . . . Read more

Hardness of Alumina is 1800 Knoop.  Sialon is  2000 Knoop and Silicon Nitride is 2200 Knoop. Diamond is 6000 – 9000 Knoop.

Although the difference in hardness does not seem a lot, the difference in wear is amazing.  The reason is in the mechanism of wear.  Wet aggregates are just hard enough to scratch and abrade the surface of alumina.  They cannot make an impression on the harder silicon nitride, however.  Consequently, it suffers practically no abrasion from even very aggressive aggregates.

The cap at right in the picture is alumina.  It has been in a high production concrete mixer using very abrasive aggregates for only 4 months.  Note the wear at the left hand edge.  The cap at left has been in a similar mixer in the same plant.  It had a similar wear problem until we replaced the cap with silicon nitride.  Consequently, measured wear is only 0.010″ over one year of operation, 50 hours of continuous operation per week with granite aggregates.  This makes its projected lifetime 10 years – an increase of 20 to 30 times!  Note the high polish on its surface, showing that the aggregates cannot score this material.

For more on different applications see Find the Best Sensor for your Appication. For a discussion of Free or Surface moisture compared with Total Moisture, click here. For an overview of all moisture related products, see Moisture Measurement.