Effect of Concrete Overlay on Deck Rating
Effect of Concrete Overlay on Deck Rating
(OP)
I have been reviewing deck rating calculations for a bridge in New England (USA), when I ran across the rating engineer using all but 3/4" of a 1 1/2" polymer modified concrete bridge deck overlay in the compression zone calculations. I'm looking for someone that might have information regarding the reliability of PMC overlay bond with the reinforced concrete deck, which would logically be the controlling criteria for including a concrete overlay in the compression zone of the deck rating.
Use of an epoxy bonding compound betwen a bridge deck and concrete overlay has traditionally produced reasonably good results, but I have no idea how well the bond would be with a PMC overlay.
Does anyone here have experience with this subject or point me in the right direction to research it?
Thanks much,
Steve
Use of an epoxy bonding compound betwen a bridge deck and concrete overlay has traditionally produced reasonably good results, but I have no idea how well the bond would be with a PMC overlay.
Does anyone here have experience with this subject or point me in the right direction to research it?
Thanks much,
Steve





RE: Effect of Concrete Overlay on Deck Rating
RE: Effect of Concrete Overlay on Deck Rating
This NE State, for which the rating is being produced, apparently has allowed A PMC overlay to be used on prior ratings. This practice is questionable in mind mind however, due to numerous delaminations and intermittent spalls of PMC overlays over the years leading to this state no loner using PMC overlays at all. I therefore am of the opinion that it would be unwise to count on the bond between the overlay and substrate to the extent that would justify use in strength calculations.
RE: Effect of Concrete Overlay on Deck Rating
RE: Effect of Concrete Overlay on Deck Rating
bridgebuster - side note, how far down below the top mat of steel would you suggest going to be able to include a SDC (superplasticized dense concrete) overlay as part of the original deck?
DOT wants to remove 1" of the orignal 7.75" deck and then slap on a 2.5" SDC overlay. There is only 1" of clear cover to the top mat. Therefore the top mat would be exposed. I keep fighting them that this isn't a good idea. But if we removed say another 5/8" to get below the top mat (transverse bars anyhow), I might be a little happier to let that slide as I could see including the overlay as part of the original deck then.
Oh ya and the original deck was cast in 1948!
RE: Effect of Concrete Overlay on Deck Rating
Coarse aggregate for a typical mix would have 90-100% passing a 1/2" sieve and 15% passing a 1/4" sieve.
Hope this helps.
RE: Effect of Concrete Overlay on Deck Rating
RE: Effect of Concrete Overlay on Deck Rating
RE: Effect of Concrete Overlay on Deck Rating
RE: Effect of Concrete Overlay on Deck Rating
RE: Effect of Concrete Overlay on Deck Rating