Measuring Moisture % in Wet Concrete

Hi All,

I was with a friend at his factory, manufacturing several CONCRETE PRODUCTS.

He wants me to automate the plant's feeding/mixing area.

I have no problem with the conveyors, etc,
but when it comes to the mixer which first mixes the product (without water) and add water as per requirement, I'm confused as to the sensor used for measuring moisture level in concrete.

The existing mixer used to have a sensor which was mounted on the walls of the mixer cone, similar to microwave planar types.

Hi...I worked in the concrete industry for a long time... the most common way to measure water content in the mix is by installing probes thru insulated bushing in the bottom of the mixer tub...there are a few co's that make this equipment...check out Besser...PM me for more thoughts..

David

I too have done lots of work in the concrete industry.

Here's what I have found.
The probes and moisture monitoring were done by specialists. (it was not my decision, just how it happened)
While it is a clever way of getting the correct mix of cement, aggregates and water, in reality (especially in a high production line) the automated water measuring is too finicky.
What I mean by that is, it takes too long to decide exactly the right percentage of water.

This often leads to a bottle neck at the mixer with the rest of the plant being starved of concrete mix.

If it is just making 'one off' batches then that is fine but if it's a production line it will slow it down.

What happens at the plants I did is - they mix the first batch using the moisture sensor then switch to plc controls for the rest (taking a note of how many litres went in the first batch) and they adjust it by feeling the wet concrete.

We use a controller from Michenfelder at work for moisture control in sand. It uses conductivity