foundation system of burj al arab

Properties of Black Cotton Soil

Rich proportion of  montmorillonite is found in Black cotton soil from mineralogical analysis. High percentage of montomonillonite renders high degree of expansiveness. These property results cracks in soil without any warning. These cracks may sometimes extent to severe limit like ½” wide and 12” deep. So building to be founded on this soil may suffer severe damage with the change of  atmospheric conditions. 

As plasticity index and linear shrinkage decreased with the increase of lime content, a mixture of both lime and cement is necessary for adequate stabilization of road bases for heavy wheel loads on the black cotton soils. Previously derived results from African and Indian black cotton soils are also matched with these results.
SI No.
Description of properties
Value
1
Shear strength
soaked CBR of only 1.5%,
2.
residual strength parameter Φr
12°
3.
permeability
10−10 cm/sec
4.
Liquid limit (Indian subcontinent)
40% ~ 100%.
5.
Free Swell index
Sometimes > 50%
An increase in lime content of 0 to 9% results in plasticity index to decreases from 47% to 5% and linear shrinkage to decreases from 11 to 3.6%  respectively.

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