Geotextiles
Geotextiles
(OP)
I would like a quick opinion, based on the limited information I am giving here, on the best (i.e price and performance) type of geotextile to use on my project.
We have a site which is reclaimed land, silt/clay at depth and sand for the upper 5m. The site needs access roads and car parks with general industrial type loadings - say trucks with 40 tonne loads / 10 tonne per axle loads.
The roads/car parks will be constructed from graded crushed limestone max size 50mm. The proposal is to grade the sand to level and compact, lay a geotextile, fill with 375mm of crushed limestone in 2 layers, then lay 100mm of asphalt.
My question is whether to use a non woven geogrid ("Netlon type") geotextile or to use a woven ("Terram fabric") type. The important factors are perfromance and cost which includes the cost of the geotextile and the expected saving on thickness of subbase.
Any suggestions?
We have a site which is reclaimed land, silt/clay at depth and sand for the upper 5m. The site needs access roads and car parks with general industrial type loadings - say trucks with 40 tonne loads / 10 tonne per axle loads.
The roads/car parks will be constructed from graded crushed limestone max size 50mm. The proposal is to grade the sand to level and compact, lay a geotextile, fill with 375mm of crushed limestone in 2 layers, then lay 100mm of asphalt.
My question is whether to use a non woven geogrid ("Netlon type") geotextile or to use a woven ("Terram fabric") type. The important factors are perfromance and cost which includes the cost of the geotextile and the expected saving on thickness of subbase.
Any suggestions?





RE: Geotextiles
Manpower cost to lay the stuff, stitch sections together or overlay joints add to the area unit costs.
Think about the future. Will any trenches be dug later? This stuff is agony for those folks then.
From your information I'd say you don't need it.
RE: Geotextiles
Therefore, if your goal is to use the geotextile as a reinforcement layer, then you need to go with a woven fabric. However, there are woven fabrics that provide very little tensile reinforcement. It is important to use the correct fabric for the application.
Generally, woven fabrics are more expensive.
All that said, I tend to agree with oldestguy. The real benefit that you would get is that if the reclaimed land (fill) was not placed in a controlled manner. With woven geotextiles you would have more uniform settlement and, therefore, less potential for cracking of the pavement.
Do you have information on the placement techniques of the filling for the reclaimed land? Do you have soil boring information that indicates the relative density from one location to the next?
If you feel the fill was place in a controlled manner and you don't see much variation, then you probably don't need the geotextile.
RE: Geotextiles
thank you for your post. The specified geotextile is a non-woven geotextile and is intended as a separation between the sand and the crushed rock sub-base. I think that this separation should have an effect in reducing the required crushed rock thickness. With a clay subgrade there should be a significant saving but with sand I do not know if any reduction in thickness would be sufficient to make the geotextile cost effective.
RE: Geotextiles
The filtering is done by the fines in the mix.
Non woven fabric will stretch maybe 200 percent of original dimension before breaking and that provides insignificant reinforcement and thus insignificant affect on base course thickness needed.
In Wisconsin a well graded crushed rock base course over a
sand sub-base has been a standard pavement section for years and no need for a separating layer ever came up to my knowledge.
With the new single sized upper base course layer (to prevent rigid pavement faulting) there still is no
separation material used on the well graded base course material below.
RE: Geotextiles