Parking Lot above clay 2

[dachenglee]

In my project, the parking lot will be located above a layer of clay (4’-9’). This is an industrial development; therefore, there will be many heavy trucks park in this parking lot. I expect the parking lot’s pavement may cracked and failed, if no treatment/reclamation the underground soil. Anyone has recommendations how to treat the clay layer? Thanks.

 

[inaz]

Yea, terrible soils and heavy traffic are not a good combination.

However, lime stabilization would likely work very well. If the test slugs achieve decent unconfined compressive strengths, then the stabilized clay will be an additional layer of pavement structure. Typically a SN of .17 is used for stabilized clay. If the soil is a high plasticity CH or CL, then look at targeting +/- 5.5% quicklime of dry weight of clay.

It's not that costly if you have significant pavement area, when compared to using geogrid/geofabric.

 

[gandersen]

dachenglee:

You should consider all factors that can affect the performance of the subgrade. Lime stabilization can work under certain circumstances. Cement stabilization can also work under different circumstances. You may want to consider undercutting and replacing a portion of the clay or using some type of geogrid and stone layer. Be careful if you are in a cold climate that the subgrade has a low water table and is not susceptible to frost heaving.

I would recommend that you retain a geotechnical engineer who is familar with local practice to make the specific recommendations.

Glen

 

[BigH]

Stabilization are valid options but first I would like to know a bit more detail - say, for instance:
- what type of clay (fat, lean, etc)
- Atterberg limits and consistency index (where is the moisture content relative to the plastic limit)
- Are the clays expansive?
- Does the clay have a crust? (i.e., where is the groundwater level both now and in the past)
- What added grade will be used to achieve the parking lot level? - if the clay surface is 3 ft under the final parking lot level, the clay might not have that much influence given some select capping layer, subgrade and pavement sections.
- Are the trucks likely to be overloaded - or within the legal limits?

Get some information of this type and a better understanding of what might be required can be added to the valued comments given by inaz and gandersen.

 

[Focht3]

[blue]BigH[/blue] is right - we need more information.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[ashjun]

Hi,
The solution to your problem depend a lot on the presence of ground water table amongst other factors cited by BigH.
Regards

 

[dirtguy4]

For soft clay subgrades you may want to consider using a woven geotextiles to provide support, but [blue]Focht3 and BigH [/blue]are right, we need some more information regarding the subgrade soil properties.

 

[lallatin]

I've been involved with using geotextiles with great success for about 30 years, and they do a great job, but optimizing their use is an art. Modern methods of lime-treatment have made that procedure nearly idiot-proof as a do-it-and-forget-it procedure in new construction, and enough competition in the field has made it very cost effective if a site warrents special measures. As the other respondents note: you need more information about the "clay" before you can make an appropriate decision.

 

[eric1037]

Where is the project located? Clay and silt soils are very susceptible to frost action. Groundwater elevation is also key.