Classic Example of Pebble Delam

Classic Example of Pebble Delam

Pebble Delam on Step

Pebble Delam on Step   Drained Pool with Delam   After Delam Repair
Step Delam

This is a classic example of a pebble surface delaminated from the shotcrete sub-surface. Enlarge the picture by clicking on it. Notice the white or chalky looking material? Now look at the smoothness of the shotcrete finish under the chalky residue. I have often wondered why the shotcrete companies don’t or won’t scratch the finish of the shotcrete when it is applied, it seems to me that it would help the pebble, or plaster, bond better or achieve a tighter grip. The cause of the white chalky residue is water penetration into the pebble and its reaction with the shotcrete, this is called effloresce. This residue forms under the pebble and expands along its perimeter causing the finish material, in this case pebble, to separate or lose its bond. I find that this is most common on the rolled bond beam, rounded edge of a step or swim-out step.