Geotech AASHTO Soil Classification

[gudia]

# 10 Passing 100%

# 40 Passing 10%

#200 Passing 4%

PL = 28 and LL = 28

This is a question from the Chelapati Book 2.5.1-

Why is the AASHTO Soil CLassification A-2-4? Why couldn't it have been A-1-b?

 

[boo]

# 10 Passing 100% # 40 Passing 10%

#200 Passing 4%

PL = 28 and LL = 28

This is a question from the Chelapati Book 2.5.1-

Why is the AASHTO Soil CLassification A-2-4? Why couldn't it have been A-1-b?

use LL , PL , PI AND # 200

 

[boo]

# 10 Passing 100% # 40 Passing 10%

#200 Passing 4%

PL = 28 and LL = 28

This is a question from the Chelapati Book 2.5.1-

Why is the AASHTO Soil CLassification A-2-4? Why couldn't it have been A-1-b?

use LL , PL , PI AND # 200

GRANULAR MATERIAL-------------PASS#200 < MAX 35----------LL <41 MAX-------------PI<10 MAX THEN A-2-4

 

[FLBuff PE]

Max LL and PI for A-1-B is 6.

A-2-4 has a max LL of 40 and a max PI of 10, with 35 max passing the #200.

 

[passpepasspe]

Max LL and PI for A-1-B is 6.A-2-4 has a max LL of 40 and a max PI of 10, with 35 max passing the #200.

I am glad someone asked this question- I am struggling to understand this also...

Isn't just the PI for A-1b just 6, not LL. LL has a dash next to it. what does that mean?

Provided all the given infromation, which things do you look at first? It seems like sometimes, we don't use the # 40 sieve or # 10 data.

 

[djgint]

Plasticity index of A-1 (A-1-a an A-1-B) is 6 max and that there is no LL that means this is a non-plastic material. LL is impossible to attain on this kind of material which is coarse to fine sand that's why it's dash. The same thing on A-3.

The process of classifying AASHTO is by elimination. First start at the left side A-1 going right A-8. Once you determine the percent passing for no. 10, no. 40, and no. 200 is out of range including LL and PI you go to the next group until you reach to the right group.

On this particular problem, This is a coarse material becuse 90 percent is retained on #10 sieve. There is no way you can get a LL and PL of 28 on both because only 10 percent of the coarse fraction passed #40 seive. The material that passes #40 seive is the material that's being used for Atterberg Limits test per ASTM D4318. This is a non-plastic material, therefore this can be a A-1-b. What do you think guys?