Geotechnical Engineering Questions and Answers – Activity of Clays

Geotechnical Engineering Objective Questions

This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Activity of clays”.

1. The plasticity of clay depends on which of the following?

A) The nature of clay minerals present
B) Volume of clay present
C) All of the mentioned
D) None of the mentioned

Answer is A)
Explanation: The plasticity depends on i) The nature of clay minerals present ii) amounts of clay minerals present.

2. 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

Answer is B)
Explanation: Typical active values are kaolinite: 0.4-0.5 Illite: 0.5-1.0 Montmorillonite: 1.0-7.0.

3. Based on activity number, clays can be classified in to_______ categories.

A) Five
B) Two
C) Three
D) More than five

Answer is C)
Explanation: Clays are classified into 3 types as kaolinite, illite, and montmorillonite.

4. A clay is said to be inactive, if the activity is_________

A) <0 .75="" label="">
B) 0.75-1.40
C) >1.40
D) None of the mentioned

Answer is A)
Explanation: Clay is classified as inactive if the activity is less than 0.75.

5. Clay containing kaolinite, will relatively have a_________ activity.

A) High
B) Intermediate
C) Low
D) Moderate

Answer is C)
Explanation: Clay containing will have relatively low activity, while montorillonite have high activity.

6. Activity of a clay can be determined by laboratory test like __________

A) Wet analysis
B) Liquid limit
C) Plastic limit
D) All of the mentioned

Answer is D)
Explanation: Activity can be determined by from the result of usual laboratory tests such as wet analysis, liquid limit, and plastic limit.

7. Based on the observation made by Skempton, for a given soil __________

A) Plastic index is proportional to percent of clay-size fraction
B) Plastic index is inversely proportional to percent of clay-size fraction
C) Plastic index is equal to percent of clay-size fraction
D) None of the mentioned

Answer is A)
Explanation: In 1953 skempton, observed that for a given soil the plasticity index is proportional to the percent of clay-size fraction.

8. For a clay to be active, the activity of it should be __________

A) 0.75-1.40
B) >1.40
C) <0 .75="" label="">
D) >0.75

Answer is B)
Explanation: Based on activity number, the activity should be greater than 1.4 for clay to be active.

9. The sensitivity of most clays usually falls in a range of _________

A) 2 to 8
B) 1 to 6
C) 1 to 8
D) 1 to 5

Answer is C)
Explanation: From referring sensitivity classification table, it can be seen that clays have a common sensitivity between 1 to 8.

10. Highly over consolidating clays tends to be _________

A) sensitive
B) normal sensitive
C) less sensitive
D) extra sensitive

... Answer is C)
Explanation: This type of clay tends to have sensitive of 1(unity). Hence it is classified as in sensitive.