Polystyrene Aggregate as Drain Rock Substitute

[AKSherpa]

I am researching polystyrene aggregate for use as substitute for drain rock behind a retaining wall.

Have you used this material? Where did you purchase? Cost? Any tips or thoughts on using polystyrene aggregate as drain rock substitute would be appreciated.

Thanks

 

[swazimatt]

when you say polystyrene aggregate are you referring to concrete mixed with polystyrene, like what is used in some lightweight precast wall panels? So in this instance chunks of concrete/polly or just polystyrene chips?
Concrete as a drainage aggregate is not ideal as it is made up of small particles cemented together and when you place them as drainage aggregate the process of placing them and compacting soil around them will result in them breaking up possibly to the extent that you loose all voids or block the water path. Poly chips are just too compressible and will loose all voids during compaction

 

[AKSherpa]

I was wondering about just using the polystyrene chips, not concrete.
Thanks

 

[bimr]

Never have seen something like this used for the application that you describing. Polystyrene seems to be so light that one would never be able to keep it in place. Is there a particular material that you are looking into?

 

[TigerGuy]

How would you counteract the buoyant forces? I think we need more information.

 

[AKSherpa]

This is a detail of the particular fill situation we are currently working with. This situation appears it might have potential for a lightweight material to work as far as buoyancy.

I have also been wondering if there are other materials that might be heavier and not buoyant that could be used for drain rock substitute. I started looking into the polystyrene when I saw it on the NDS drain tile product. We encounter similar situation in other areas of our work that require drain rock such as in gthe bottom of airport light cans. We are in an area that is very remote and the cost for procesing drain rock is very high.

Thanks

 

[BridgeSmith]

You should consider a sheet drain behind the lagging, bring the reinforced fill up near it, and eliminate the drainage rock.

With the depth to fixity shown, that guardrail won't have much resistance.

 

[swazimatt]

There are other alternatives that could work, polystyrene chips blow away during construction, but more importantly will compress when you compact above them and there will be no voids for water to run through
there are other alternatives like Link

 

[swazimatt]

PS that may not be the exact product, but there are numerous suppliers of that "egg-crate" drainage roll

 

[LittleInch]

Tried "Leca"?

E.g.

https://www.cpa-horticulture.co.uk/...lTWG_QI4XQbYRjO36ZsWNXezEjT_ZQSwaAv28EALw_wcB

Can you provide more information on what you mean by polystyrene aggregate as it's not clear if you mean the really lightweight crushable fill you get in packaging or t something else.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[AKSherpa]

LittleInch,
I am loking for something similar to the packaging "peanuts" but more durable and heavier. I thoiught maybe something existed out there these days that could be used as a drain rock or filter media for backfilling walls or used in onsite wastewater trenches. It does not have to be polystyrene based, I started there since I saw some products on the internet that used "polystyrene aggregates" wrapped around drain tile.
Thanks

 

[AKSherpa]

The below from Infiltrator Water Technologies is what I am referencing. I was also wondering if there might be something similar that is heavier than water.

EZflow Pipe Drainage System | Infiltrator Water Technologies

EZflow drainage products consist of a gravelless sewer pipe with geosynthetic aggregate. The EZflow leach line pipe maximizes system life and performance.

www.infiltratorwater.com

Or, maybe an expanded foam that is permeable and manufactured onsite could be used behind a retaining wall in substitute for standard "Drain Rock"??

 

[JJM63]

I'm assuming it is solid polystyrene pieces, not styrofoam or packing peanuts. Those would settle under the weight of the Type C material above them. If you need a lightweight aggregate, expanded shale might be more durable.

I agree with Bridgesmith about the deflection distance of the rail.

Formerly known as ACTrafficEngr

 

[geotechguy1]

Chuck some in a bathtub full of water and tell me what happens. You're going to put this material where the water is being directed?

You need to have a re-think of this deeply flawed idea.

 

[LittleInch]

Well. it might work, but clearly you need to encase it in a geotextile set of bags or tubes.

 

[eyeforgeotech]

Like others have suggestion, a sheet drain would be lightweight, well tested in the field and easy to use. Depending on where you are located, contact a geosynthetic company in your area. There are lots on the market. One I quickly found: https://www.awd-usa.com/drainage-applications/retaining-wall