Resilient Modulus of soils

[nagatalluri]

For Calculating the resilient modulus of soils AASHTO recommends using Mr=1500*CBR for soils with CBR<10

Is there any correlation for soils that have higher CBR values for estimating the resilient modulus (Mr).

Thanks
NT

 

[fattdad]

We limit the correlation to a maximum value of 15,000, whihc I think is typical for DOTs using AASHTO '93 pavemetn design.

f-d

ípapß gordo ainÆt no madre flaca!

 

[nagatalluri]

Fattdad

Thanks for your quick response.

NT

 

[Ron]

The AASHTO 2001 Design Manual suggests 2555 x cbr^0.64. If you plot a curve of this relationship, you will see a slope change at about CBR 25. The curve gets steeper.

 

[nagatalluri]

Ron, does that mean we can use the correlation (2555*CBR^0.64) up to CBR of 25?

Thanks
NT

 

[Ron]

No. Actually the correlation is supposed to be valid for any CBR range, it is just that the curve becomes steeper with higher CBR values. Intuitivel that makes sense. The older 1500 x CBR had a limited range.

 

[nagatalluri]

We generally use this equation for evaluating the resilient modulus of Base material for AASHTO low volume road design.

Can the same equation be used for subgrade materials?

Thanks
NT