Sunday, September 26, 2010
Followup on condition of Chinatown bridge
by Larry Geller
I did check with experts on concrete spalling and shared my cellphone pics, hoping to learn if my suspicion in Chinatown bridge railing neglected and crumbling (9/22/2010) is valid.
Keeping in mind that this followup is still based on photos and not a visit, the verdict is that there are signs of concrete spalling but that it is difficult to determine if the rails or bridge are structurally compromised. To do that, a structural engineer would have to visit and inspect the bridge.
Also, the expert emphasized the importance of periodic inspection of bridges and other structures.
As you will recall, the city sent someone to inspect following my inquiry. I strongly feel they should already have noticed and repaired what those photos demonstrated—spalling, that is, blocks of concrete falling off, exposing the rusting reinforcing bar (rebar) inside. The rebar swells and expands when rusted, exerting tremendous internal pressure on the concrete, causing it to crack and often to fall off the structure (spalling).