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My first, broad question is this: Do we have any recommended method for tying down temporary barrier to a concrete pavement/bridge deck that has been overlaid with asphalt? I've read some reports where tying down through an asphalt overlay is not recommended. But I haven't come across any reports that say such practice is allowed.
As a follow-up, do you believe that the asphalt pin tie-down could be used on a concrete pavement that has been overlaid with asphalt, if the pavement was first drilled (say with a 1.625" bit) down to the subbase to allow for pin penetration?
Finally, is it possible to constrain the barrier through the vertical bolt holes with drop-in anchors or screw-in anchors?
|Date||June 25, 2007|
I have some short answers for your questions.
|Date||July 2, 2007|
Do you have any recommendations on what size of drill bit should be used to pre-drill the concrete for the asphalt pin?
As a follow-up to my previous question " would it be feasible to use the asphalt pin tie-down directly on top of full-depth PCC pavement (no asphalt overlay)?
|Date||July 11, 2007|
With regards to you first question about the size of the dill bit used for the asphalt pin, I would recommend that it be only 1/16" to 1/8" larger than the pin diameter. This would be a maximum bit size of 1.625". The hole in the pavement needs to be kept as small as possible to make the pin engage as soon as possible during the impact. For installation, it may be easier to set the barriers down and then drill through the existing holes in the barrier as guides to make sure the pins will fit.
Your second question asked if it would be feasible to use the asphalt pin tie-down directly on top of full-depth PCC pavement. We think that this might be acceptable if it was just being used on a roadside installation, but we would rather see you use the bolted tie-down option we developed for concrete. This option has been tested and we know how it will perform. We think that the asphalt pins may work as well, but they will not provide as effective restraint as the bolted tie-down. We would definitely recommend using on the bolted tie-down on a bridge installation.
|Date||July 24, 2007|
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