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Expansion Index

Joined
Jun 24, 2013
Messages
6
Location
New Mexico
While exploring soils reports I ran into this problem.

2009 IRC R403.1.8.1 Expansive soils classification.

Line 4 says, Expansion Index greater than 20, determined in accordance with ASTM D 4829. Which I am reading that over 20 in a (test result) is considered expansive.

When I reference ASTM D 4829 5.3, Significance and use, I find a table that does not quite jive with code reference.

0-20 is classified as very low potential expansion.

21-50 is classified as low potential expansion.

and table continues.

Our structural engineer says that the most important test is the expansion index for foundation design dealing with expansive soils.

When I asked him about this code reference he seem puzzled and confused with this question from me and did not answer. He is 80 years old.

On a similar vein of thought, I am seeing the lack of the expansive index on several soils reports that I am reviewing for repair work on houses build on expansive soils.

Does one have to pay extra to have this test in a soils report?

Can some one straighten me out ?
 
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