Deck Repairs in an Existing Latex Modified Concrete Overlay

[cnstengineer]

When an existing concrete t-beam bridge was widened about 25 years ago, a variable depth un-reinforced latex modified concrete overlay was placed over the existing t-beam bridge. The depth of the overlay ranges and is about 5" thick at it's greatest depth. Today there is visible spider cracking on the latex modified deck surface over the old bridge. When the deck was recently sounded, there were areas around the cracking that did not sound hollow (like a normal delaminated area), but still had a dull, dead kind of sound. Other areas outside of the craking had a nice solid "ping" sound. Any theories on what the "dead" sound is resulting from?

 

[bridgebuster]

It could be delaminated or it could be debonded from the deck. In the late 70's LMC was highly touted. 15 years later some DOT's stopped using it because of bonding problems.