1. What is the best possible method to stabilize desert sand?
a) Proportioning
b) Lime
c) Cement
d) Bitumen
Explanation: There is a problem of water scarcity and soil-cement stabilization method cannot be used. Desert sand consists of fine sand particles and proportioning is difficult. Lime is also not employed. So, hot sand-bitumen is the most possible and preferred method.
2. The mechanical stabilization of soil does not depend on which of the below?
a) Compaction
b) Consolidation
c) Presence of salts
d) Gradation
Explanation: The mechanical stabilization of soil does not depend on consolidation. The major factors affecting the process of mechanical stabilization of soil are mechanical strength of aggregates, gradation, properties of soil, presence of salts and compaction.
3. Which of the below gives the theoretical gradation for maximum density?
a) \(P=100(\frac{D}{d})^n\)
b) \(P=100 (\frac{d}{D})^{1/n}\)
c) \(P=100 (\frac{d}{D})^n\)
d) \(P=100 (\frac{D}{d})^{1/n}\)
Explanation: The right equation for obtaining the gradation for maximum density is given by \(P=100 (\frac{d}{D})^n\). In the equation, P represents the % finer than diameter d, D is the diameter of the largest particle and n is the gradation index.
4. What is represented in the Y-axis of the distribution curve plotted for Rothfutch’s method?
a) Desired gradation
b) Sieve size
c) Percentage retained
d) Percentage passing
Explanation: Rothfutch method is used for proportioning of the soil. Various grades of soils are mixed together to obtain the most stable mix. A graph is plotted with percentage passing on the Y-axis and sieve size on the X-axis.
5. What proportion of soft aggregates to soil gives the best result?
a) 1:2
b) 2:1
c) 1:1.5
d) 1.5:1
Explanation: The soft aggregates are weak in taking strength, impact and crushing imposed by the heavy loads. So, using mechanical stabilization, it is mixed with soil to make it perform better. The best proportion for the same has been found out as 1-part soft aggregate to 2-parts soil.
6. ______ method can be used when mixing three different materials
a) Triangular method
b) Rothfutch method
c) Mehra method
d) Tertiary method
Explanation: Triangular method is used to perform proportioning when there are three materials being used. Each material can be designated or classified as coarse aggregate, sand or fine. Then their percentages are marked on the triangular chart and the proportioning can be carried out.
7. What is the gradation index for a spherical shaped particle
a) 0.5
b) 1
c) 0.3
d) 0.1
Explanation: The gradation index value ranges from 0.3 to 0.5 and it depends on the shape of the particle. The sediment analysis is done on the basis of Stoke’s law, which assumes spherical particles. The gradation index for spherical particles if found to be 0.5.
8. Which of the below is not a typical stage of a mix?
a) No fines
b) Little fines
c) Equal fines
d) Excess fines
Explanation: There are three typical stages of mixes. They are compacted aggregates containing no fines, compacted aggregates with fines filling voids and compacted aggregates with excess fines. There is no stage of an equal amount of aggregate and fines.
9. The method of soil stabilization using soft aggregates was suggested by Fuller.
a) true
b) false
Explanation: The method of stabilization using soft aggregates was formulated by S.R Mehra and it has been standardised by BIS. Mehra used brick aggregates as soft aggregates for the soil stabilization.
10. Which option represents the steps involved in mix design procedure of mechanical stabilization?
a) Gradation, proportioning and index property
b) Gradation, proportioning and stability
c) Gradation, proportioning, stability and index property
d) Gradation and proportioning
Explanation: For the mix design procedure, there are four steps involved. The first one being gradation, then proportioning, carrying out tests for stability and index properties of the soil mix.