ᐅ Efflorescence on Concrete Pavers When Using Recycled Concrete Aggregate

Hello everyone.

We are currently wondering whether using crushed stone with a rating of RC is sufficient, or if it really has to be the mineral mix that costs more than twice as much.

We will be installing anthracite concrete pavers.
The surfaces will be fully exposed to the weather, meaning they will get wet from rain.

What are your experiences with this?

RC gravel is completely sufficient. If you are unsure, add an extra layer of geotextile in between. Why would anything effloresce?

Because I have heard from several sources that crushed construction debris can release substances that may cause efflorescence.

I cannot confirm that. Depending on the load, 25-30cm (10-12 inches) of reinforced crushed stone, 4cm (1.5 inches) of crushed sand-gravel mixture (I prefer using only gravel), and then the paving on top.

I can’t imagine that. I have especially heard that anthracite-colored paving stones tend to effloresce, but why would that have anything to do with the subbase? I’m more inclined to think it’s due to the paving stones themselves. Probably the only way to minimize the risk is to avoid using the cheapest materials.

One could say that sounds like an excuse... how is anything supposed to move upwards against gravity, against the flow of water, through the gravel?