Puzzled 1

[nbucska]

Next to me the parking lot of an old apartment building
is being remodeled/repaved. They replaced the top 2 feet
of dirt with crushed rocks on a thick plastic.

I wonder, why ? Any guess ?

<nbucska@pcperipherals.com>

 

[Rjeffery]

The subgrade of the parking lot may have been unstable. the thick plastic is probably a geotextile that acts to spread the load over a greater area.

Hope this helps.

 

[ACtrafficengr]

Sheet plastic or polyester fabric?

Geotextiles are used for many different things in construction. What is the underlying soil like? If it is silty or clayey, they could be using filter fabric to keep the fines (particles under about 1/200&quot from migrating up into the crushed stone. This plogs up the voids between the particles and messes up the drainage. Bad drainage contributes to weak base conditions, freeze-thaw damage, rutting and the like.

If it was plastic sheet, I haven't the foggiest.

 

[KRSServices]

It sounds to me as though they placed a geotextile. Did they then place gravel on top of it, compact and then pave? Where is the water table? What was the asphalt condition prior to the work? A guess is that the work is being done to reduce the effects of flexure by providing a sufficient base structure under the asphalt. I have had similar designs under roads for the purpose of providing sufficient structure. KRS Services

http://www.krs-services.com

 

[RWF7437]

Probably the underlying soils are weak and/or unstable. The thick &quot;plastic&quot; is most likely a geotextile fabric which helps to bridge soft spots and prevent uneven settlement. The thick base rock layer is also a way to strengthen the pavement structure and will be topped with a wearing course of either asphaltic concrete or Portland cement concrete.

You can learn more about geotextiles and their many uses in road work and other engineering applications. Try searching the web using &quot;geotextile&quot; or visit web pages for companys that make them such as Monsanto, Amoco and 3M.

Russ Faust