New sidewalk over existing

Old 10-02-09, 07:23 AM
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Join Date: Dec 2005
Location: USA
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New sidewalk over existing

I am planning a new poured concrete walkway and I have a couple of questions.

My existing walk consists of 3'X5'X4" concrete slabs with exposed aggregate. The slabs are separated by PT 2X lumber. Steps are 6X PT ties. I want to remove all the PT and pour a continuous walkway on top of the existing concrete. my plan is to add 3" of concrete and use control joints every 4'. Do I have to be concerned with a bond between the existing and the new pour? Can I get away with 2" over the slabs instead of 3"?

My other question has to do with slope. I will be adding an additional 15' to the existing walk. This new walk is sloped nearly 2'. Can I make this pour continuous or will the concrete flow down the slope?
Old 10-22-09, 04:49 AM
Join Date: Oct 2009
Location: California
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I noticed you had no replies to your query and I thought I would chip in what I did know while you wait for someone to give a more complete answer.

The new cement will NOT bond with the existing cement. To connect them, drill holes in the existing cement (hammer drill and masonry bit -- get the best quality bits you can find -- hard cement and aggregate will chew up a cheap bit real fast. Bosh masonry bits are the best brand I have found at home improvement stores) and cement anchors (Simpson makes anchors and epoxy). I don't know if it's recommended but you might be able to save a few bucks by using rebar with the epoxy.

It is possible to pour a 15' by 2' rise sidealk in one pour. However, if you don't pour cement for a living, you might not want to try this yourself. I once tried to pour a more gentle slope myself and it was a disaster. When I hired the pros to fix my mess, they made it look easy.


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