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

* Ability to batch the correct weight of sand regardless of water content
* Reduction in number of spoilt batches
* Ability to set alarm for high moisture levels

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. Water is effectively being weighed and not dry materials.

Moisture sensors can measure moisture levels in materials from bins or silos, conveyor belts and vibratory feeders. The sensors are placed directly in the flow of material, and take 25 readings per second as the sand or aggregate flows over or around the ceramic faceplate. These measurements ( readings) are then fed back 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 underneath a bin. The most popular sensor for this type of mounting is the Hydro-Probe II which takes readings as the sand or aggregate is released from the bin and flows over the sensor head. For plants where it is difficult to locate the sensor in this position, good results have also been achieved by mounting the sensor inside the bin.

For measurements of moisture in sand and aggregate on conveyors and belt feeds, a Hydro-Probe II or a Hydro-Probe Orbiter can be mounted above the belt. Readings can then be taken as the material passes along the belt, flowing either side of the sensor.