Considerable cost savings can be achieved in the manufacture of concrete, sand-lime and clay blocks when using a novel moisture measurement method that works. According to the supplier, product quality can be improved significantly if the water content of recipes for block production can be kept stable in the long term, with a variation of only ± 2 l/m³, by using radar-based aggregate moisture probes.
When producing blocks, however, the only parameter that is routinely measured is the moisture content of sand. It should be noted, though, that a basic water content deviation of up to ± 2 l/m³ from the specified value can be adhered to if the moisture content of other aggregates is also accurately measured. In reality, ensuring long-term compliance with the required water content poses a big challenge. Manufacturers often need to adjust the settings of their equipment and machinery manually to be able to adhere to the specified basic deviation.
Xella Baustoffwerke Rhein-Ruhr GmbH in Bocholt, Germany, is one of the producers where the functioning of this principle can be viewed in detail. This plant uses a Sono Vario sand moisture probe operated in automatic mode.
Sono probe as a moisture “tomograph”
The new Sono technology uses aggregate moisture probes to make concrete recipes comply with a water content deviation of ± 2 l/m³ whilst ensuring long-term stability. The Sono TDR method relies on a “guided wave radar” that travels along a radar conductor almost at the speed of light whereas the measuring field propagates into the material above the probe in “slices”. Within certain limits, the measuring field created by Sono probes also copes with smaller amounts of material above the probe head if the fill height is low. On the other hand, the measuring field also propagates into greater material volumes if larger quantities are subjected to measurement. This method evens out influences on the measuring field due to excessively large gravels or fine particles whilst minimizing external impact by equipment parts.
The Sono-Vario Xtrem version features a hardened, exchangeable probe head made from a special ceramic material that resists the impact of 32 mm gravels even from greater heights. The material to be measured is captured in a “slice-by-slice” process similar to a CT scan.
Innovative technologies should provide improvements whilst also lowering capital expenditure and life-cycle costs. The state-of-the-art, revolutionary Sono method opens up a new era of moisture measurement.