Question

Which of the following is incorrect about the identification of CNS material?

(a) The CNS material can be identified by using A-line chart

(b) The permissible deformation of the CNS layer is 20 mm

(c) The swelling pressure should  not exceed 10 KN/m^2

(d) The soil with liquid limit less than 30% and plastic index less than 15% is considered suitable

This question was posed to me in homework.

The origin of the question is Lining of Canals in Expansive Soils topic in portion Lining of Irrigation Canals and its Economics of Irrigation Engineering

Answer 1

Right option is (d) The soil with liquid limit less than 30% and plastic index less than 15% is considered suitable

Explanation: The A-Line chart is used for general identification of CNS material and the only data required is liquid limit and plastic limit. The soil falling in the zone between liquid limit 30 to 50% and plastic limit 15 to 30% is considered suitable to be used as CNS material.