Pouring New Sidewalk over Existing Sidewalk

[sreeise]

I have a project where a contractor wants to pour new sidewalk over the existing. The existing is in fairly bad shape. He wants to place a layer of sand between the two. My idea was to make him put an epoxy coating over the existing sidewalk to keep the two layers from bonding to each other. Any ideas?

 

[SlideRuleEra]

For best results, have the Contractor remove the existing sidewalk and place a properly compacted base before pouring the sidewalk. The sand layer might work, but why take the risk?

Concerning the proposed epoxy coating, placing new concrete directly on old concrete that is in poor condition is asking for trouble - whether the layes are bonded or unbonded.

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[cvg]

you need to determine why the existing sidewalk is in bad shape. For instance, if it had poor subgrade compaction, remove and replace with new concrete (after fixing the subgrade). If it is just old and suffering from years of weathering, maybe an overlay would be OK. If you have a chemical reaction with the agregate in the existing concrete which is causing it to deteriorate, you should definitely remove the old.