SOIL MECHANICS EXAM – COMPACTION questions with correct answers

What happens during fill operations? CORRECT ANSWER When fill operations are taking place the new soils are usually compacted in place to improve the strength characteristics. What is compaction CORRECT ANSWER Compaction in general terms is the densification of soil by the reduction in voids (mainly air) by mechanical means. How do you define degree of compaction? CORRECT ANSWER the dry unit weight Describe the dry unit weight CORRECT ANSWER - It increases with compaction - It will also increase with an increase in moisture content. This is because water acts as a softening agent. However, after a certain water content (optimum water content), additional water will reduce the dry unit weight. How to measure compaction? CORRECT ANSWER - Standard Proctor Test (Lab) - Modified Proctor Test (Lab) What is the history of the Standard Proctor Test? CORRECT ANSWER Developed in the 1930's to simulate field compaction effort, in the laboratory What is the equipment used in the Standard Proctor Test? CORRECT ANSWER - 1/30 ft^3 mold - 6.5 lb hammer with a drop of 12 in. What is the simplified procedure when completing the standard proctor test? CORRECT ANSWER - The soil is mixed with a specific amount of water - Soil is compacted in 3 layers by delivering 25 blows per lay