Lightweight Aggregate, LWA, Typical CBR Values?
Lightweight Aggregate, LWA, Typical CBR Values?
(OP)
Where can I find typical CBR values for Lightweight aggregate? We would like to use a LWA for a road subbase but can not find documentation of the CBR values for any of the products that we have evaluated.






RE: Lightweight Aggregate, LWA, Typical CBR Values?
If you are trying to cut down the overburden weight on some soft underlying soils, it would be better to do that in the subgrade, not the base. That can be done in a variety of ways, including using cellular concrete and polystyrene in extreme cases.
Cellular concrete alone is a good choice for a relatively high modulus material that will significantly reduce the weight of overburden (typical soil unit weight - about 100 pcf...typical cellular concrete unit weight - about 40 psf); keeping in mind that it isn't cheap. But then, if you have adverse subsurface soil conditions, a successful solution of any sort won't be particularly cheap.
RE: Lightweight Aggregate, LWA, Typical CBR Values?
http://www.escsi.org/
Try the "Geotechnical" and the "Literature & Technical Documents" areas of the website.
www.SlideRuleEra.net
RE: Lightweight Aggregate, LWA, Typical CBR Values?
Ron, I didn't give you the full story. The road that we are providing a section for his on top of a parking structure. We are using the LWA for the subbase of variable thickness and then using base and surface asphalt on top of that. We are attempting to reduce the load on the garage slab that has already been built without taking into account the deadload of the pavement section above it.
SMP
RE: Lightweight Aggregate, LWA, Typical CBR Values?
You might want to consider a hybrid of the cellular concrete for this application. You could add some lightweight aggregate to the cellular concrete and still achieve a low unit weight and relatively high strength. You could then cover that with a relatively thin layer of polymer concrete, effectively cutting out your subbase layer.
RE: Lightweight Aggregate, LWA, Typical CBR Values?
RE: Lightweight Aggregate, LWA, Typical CBR Values?
I'm sorry but I don't have a very good understanding of lateral stresses at the bottom of the asphalt layer. It is our plan to use the Stalite product under the asphalt layers to serve as our subbase with a CBR of 30 or higher. The Stalite will be a variable depth to a maximum of about 18". I'm hoping that this section will be sufficient. I have a phone call into Stalite to confirm this. I'll mention the lateral stresses to their engineer to make sure that it will not be an issue for us.
I reviewed the Elastizell product and I can see what the advantages would be. What is the typical thickness for the concrete carrying slab? I think that since we don't need much fill (18") that we may be okay with the Stalite alone.
Thank-you both for your responses. They have been very helpful!
SMP
RE: Lightweight Aggregate, LWA, Typical CBR Values?
RE: Lightweight Aggregate, LWA, Typical CBR Values?
The County may allow us to reduce the asphalt layers of 2" surface and 5" base course, but it would require a lengthy review process that we are hoping to avoid.
One idea that we are tossing around is laying some type of geomat on the LWA to contain it so that we may pave on it. This would eliminate the additional 4" of stone that is only being put in place to contain the LWA. Does this sound like a solution that would address the issue of elevated lateral stresses? Does anyone have a product in mind so that I can pursue this solution through one of their technical representatives?