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Title: GK2 Standard Letter



I am trying to figure out what role carbonation may have played in a structure that has experienced debonding of a 2 inch thick concrete topping that was placed on 4 inch thick precast planks (roof structure).

I had a lab do analyses on a number of samples including ones in which the debonding had occurred and one sample where the topping and plank were still bonded.

The staining with the phenolphthalein indicator solution showed significant carbonation depths for the debonded topping and plank interface surfaces (debonded a while ago and carbonation occurred), but for the still bonded sample it showed carbonation on the top plank surface and NONE on the bottom topping surface.  In other words, the plank top surface appeared to carbonated prior to placement of the topping.

I am wondering if anyone has dealt with the effects that carbonation may have on the ability of fresh concrete to bond to a carbonated surface.  Would it reduce the potential bond, or have no discernable effect?


I’d welcome comments if you have any.





Terangue *Tiger* Gillham, PE
GK2, Inc.

tiger(--nospam--at) <