What is the procedure for expansive soil testing?

[EagleEye]

I am inquiring about how one tests a residential property for expansive soil conditions or other conditions. Had an associate refer to it as "soil penetration testing". I would like to find some basic testing methods.

Thank you in advance.

 

[Ashayeri]

expansion test can be done by consolidometer apparatus, the standard for the test is ASTM D4546.

 

[sgeotek]

Expansion Index tests may also be performed on bulk samples obtained from the near surface soils and are evaluated using ASTM D4829 & Uniform Building Code UBC 29-2 test methods.

 

[Focht3]

Other methods of evaluation are available. Penetration testing is useless - you might as well be witching for water. The EI test gives you a "worst case" analysis; may not be appropriate for your problem (but can be very useful in design.)

Is this a forensic evaluation, or new construction?

 

[sc]

Lots of rules of thumb help out here;

1. Expansive soils are generally higher in plasticity.
2. Clays are generally the problem.
3. Climate is a major influence (Temperate, semi-arid or arid)
4. Water content at the time of testing may often be irrelevant.
5. Rainfall is another major influence.

For 1 and 2 determine the plasticity of the soil by rolling a "moist" sample (near plastic limit) between thumb and fore finger. If it ribbons down to a size less than 2mm without breaking, then it is more than likely highly plastic. As a result this soil may expand when wetted and contract considerably when dried (ie a house build on it).

For 3, 4 and 5 a general rule is that the more arid the area the greater the depth related effect of the soil movement and related water tables. For the area that I live in we need to determine the soil type down to 3.00m because of the need to confirm the plasticity of the soil in our semi arid zone and the potential effect of extreme soil moisture conditions. In other areas further south the depth of "testing" is only 1.50m as the effect of extremes in soil moisture is greatly reduced due to more consistent and higher rainfalls.

You will need quite a bit of experience in the field to become proficient at determining soil conditions and reactivities.

As an additional note we rarely lab test soils as the cost is prohibitive and time consuming due a lack of labs in our area. There are some Australian Standards (

http://www.standards.com.au)

that assist in providing guides with respect to determining soil type and reactivities.

Regards

sc