NEED HELP UNDERSTANDING IBC CLAUSE (EXPANSIVE SOIL)

[Tstruct]

Hello everyone,
Please have a look at the attached image of IBC 2021 clause.
I have the following doubts:
It says all four criteria need to be fulfilled for a soil to be expansive whereas it also says if test mentioned in point 4 is conducted then points 1,2 & 3 not required to be fulfilled. What does it mean? Isn't there a contradiction in the statement? It is saying to meet all four points, but also saying if point 4 is conducted point 1,2 & 3 are not required. How should I proceed?

Thanks.

 

[HTURKAK]

Point 4 literally means Expansion Index test is compulsory and if > 20 sufficient condition by itself. My interpretation of the clause 1803.5.3 is , conduct expansion index test. If Expansion Index > 20 , no need to look the other tests. The soil is expansive. If less Expansion Index is less then 20, then conduct also the other test to decide if soil is expansive ( 1,2,3) .

The following para. copy and paste from IBC Handbook Illustrated .

1803.5.3 Expansive soil. Expansive soils are those that shrink and swell appreciably because of changes in soil moisture content. Reference should be made to Section 1808.6 for mitigation methods and design for expansive soils. Frost heave is not considered in this section. Expansive soils are present or prevalent in all 50 states of the United States and in many other countries around the globe. Soils must meet all four of the criteria to be classified as expansive, not just a high Plasticity or Expansion Index. The section allows two different ways to identify expansive soils. The first option involves meeting four criteria: (1) Plasticity Index (PI) of 15 or greater determined by ASTM D 4318; (2) more than 10 percent of the soil particles pass a No. 200 sieve determined by ASTM D 422; (3) more than 10 percent of the soil particles are less than 5 micrometers in size as determined by ASTM D 422; and (4) an Expansion Index greater than 20 according to ASTM D 4892. The second option is to determine if the Expansion Index (according to ASTM D 4892) is greater than 20. If the Expansion Index is
determined, the first three tests need not be conducted. In other words, Expansion Index > 20 is both a necessary and sufficient condition by itself.

 

[MintJulep]

It's badly written.

As written, of the soil meets the conditions of items 1, 2 and 3, but item 4 returns less than 20 it's not expansive.

So, why did you need to do 1, 2 and 3?

=OR(AND(A, B, C, D), D)