Concrete Expansion Joint Question


I have a sidewalk that runs at at 90 degree angle to my driveway. There was a felt expansion piece where they meet, but it has deteriorated. I dug out the rotted stuff.
The gap between the sidewalk and driveway is about 3/4" wide. Too narrow to use two 1/2" expansion strips, but too wide for one 1/2" strip to fill the gap. I've been unable to find 1/4" strips.
A friend suggested using one strip and filling the reamining gap with sand. Will this work? If so, does it matter what type of sand I use: playground, leveling, paver locking sand?
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snipped-for-privacy@verizon.net wrote:

At his point, nothing is required to be in the joint. If you are concerned about looks, you can fill it with most anything that pleases you. They make a gray colored flexible caulk especially for sealing expansion joints if you so desire.
Bob
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wrote:

I agree with Bob. Also, there are fibrous joint filling materials that one can use and then finish off with caulk. (In those cases where caulk alone would require too much material)
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Bob, I was under the impression (apparently wrong) that if water gets into the gap and under the sidewalk, winter freezing and thawing could cause the gap to widen or cause the sidewalk to heave and end up higher than the driveway instead of level with it. I thiought the expansion joint was meant to prevent that. Is this incorrect?
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The expansion joint was originally placed to allow space for the concrete to expand and contract without breaking or pressuring each other. You are correct that joints in pavement should be sealed to prevent water/ice/subsoil saturation/etc. This can be accomplished with backer rod and polyurethane caulk or tar sealant (probably what you see the city crews use). It is amazing to me how much concrete does just fine without much of anything. Yours seems to have done fine as a fiber expansion joint does little to seal the joint. True tar joints would not rot out.
______________________________ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net

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Thanks for the tip about backer rod and polyeurethane chaulk. I didn't know what "backer rod" is so I Googled it and found good instructions on using it along with the caulk to fill the gap. It looks easy to do, so I will try it.

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I'm not Bob, but the water issue is a possibility. You'll never get a perfect seal but ice can do strange things from the expansion. I'd fill the gap at least as well as I could with something flexible and top it with the caulk.
That felt material is actually made from sugar cane. It was stamped right on the last batch that I bought.
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