Moisture Measurement in Aggregates and Sand

Hydronix sensors were originally designed for the ready-mix and pre-cast concrete industries to increase the accuracy of batching and slump control. However, microwave moisture measurement has also proved to be invaluable in other industries that use sand or aggregates during processing.

Benefits

• Reduction in number of spoilt batches
• Ability to batch the correct weight of sand regardless of water content
• Ability to set high or low moisture levels alarms

Modern plants can weigh aggregates with an accuracy of up to ± 0.5%. If the amount of moisture in a batch of sand or aggregates varies from between 2% to 10% then this will affect the accuracy and proportions of the weighed materials since water is effectively being weighed and not dry materials.

Moisture sensors can measure moisture levels in materials being discharged from bins, on conveyor belts or within vibratory feeders. The sensors are placed directly in the flow of the material, and take 25 measurements per second as the sand or aggregate flows over the ceramic measurement surface. These measurements are then transmitted to the plant control system in real time. This allows the manufacturer to accurately control water addition during processing and ensures that batches are of a consistent quality, while reducing the level of wasted material.

Hydronix sensors have a variety of mounting options and can be installed in different locations depending on the individual requirement of the plant. The best results can be achieved by mounting the sensor either in the neck of a bin or underneath the gate. The most popular sensor for this type of mounting is the Hydro-Probe which takes readings as the sand or aggregate is released from the bin and flows over the sensor faceplate. If it is difficult to locate the sensor in this position, good results have also been achieved by mounting the sensor inside the bin.

To measure moisture in sand and aggregates flowing on conveyors and belt feeds, a Hydro-Probe or a Hydro-Probe Orbiter can be mounted above the belt. Readings can then be taken as the material passes along the belt, flowing around the sensor. Typical installation examples can be found on our Hydro-Probe Installation page.

Moisture Sensor located under Aggregate Bin

Hydro-Probe installed above sand conveyor belt