Question

The typical activity value of illite, present in clay is________

(a) 0.4-0.5

(b) 0.5-1.0

(c) 1.0-7.0

(d) 2.7-5.3

This question was posed to me in an international level competition.

The above asked question is from Activity of Clays topic in chapter Index Properties Determination of Geotechnical Engineering I

Answer 1

The correct choice is (b) 0.5-1.0

To explain: Typical active values are kaolinite: 0.4-0.5

Illite: 0.5-1.0

Montmorillonite: 1.0-7.0.