# Concrete Sidewalk over Existing Asphalt



## SiteCivil85 (Feb 4, 2010)

Has anyone ever placed concrete sidewalk directly over existing asphalt? My concern is cracking due to lack of drainage in the sub-base, however was wondering if anyone has ever done this and if so, how they constructed it.


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## CONCRETE MIKE (Jan 11, 2010)

SiteCivil85 said:


> Has anyone ever placed concrete sidewalk directly over existing asphalt? My concern is cracking due to lack of drainage in the sub-base, however was wondering if anyone has ever done this and if so, how they constructed it.


I have poured over asphalt in the past.(White topping) We paved 5" of concrete fiber reinforced over asphalt. We prepared the base by paving approx 1" of asphalt over exsisting road to cover cracks. Then slipformed the concrete.


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## Vinny (Jul 21, 2007)

I have a steel reinforced 8" slab over asphalt (asphalt had no cracks but some softness from exposure to hydraulic oil) and the concrete is as good as the day I installed it


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## JDavis21835 (Feb 27, 2009)

White topping has been experimented with in this area by the state DOT. It works well, but is cost prohibitive. In general, with a good base, drainage, and adequate concrete, you should see good results.


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## jlhaslip (Dec 31, 2009)

how do you compact the asphalt?
I think it best to remove the asphalt and prep the ground.


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## Tinstaafl (Jan 6, 2008)

jlhaslip said:


> how do you compact the asphalt?


A big machine thingy with rollers. You know, when it was laid? :whistling


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## jlhaslip (Dec 31, 2009)

O-o! 

The round and round do-hickey thing-ma-bob with the drunk guy steering it... gotcha...


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## JDavis21835 (Feb 27, 2009)

jlhaslip said:


> how do you compact the asphalt?
> I think it best to remove the asphalt and prep the ground.


All this should have been done before the asphalt was placed, and compacted. So why remove the asphalt if it is in decent shape?


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## wheeler (Feb 8, 2009)

some jurisdictions frown on covering asphalt from an environmental perspective.

technically speaking if the grades can increase and the asphalt was originally placed on suitable bearing material, which you could test, you could then rubblize the asphalt in-place, cover with suitable base, compact with a "big machine thingy with rollers" to grade and proctor, and march on-smartly with a reinforced concrete walkway.


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## CONCRETE MIKE (Jan 11, 2010)

wheeler said:


> some jurisdictions frown on covering asphalt from an environmental perspective.
> 
> technically speaking if the grades can increase and the asphalt was originally placed on suitable bearing material, which you could test, you could then rubblize the asphalt in-place, cover with suitable base, compact with a "big machine thingy with rollers" to grade and proctor, and march on-smartly with a reinforced concrete walkway.


 :clap:


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