Question

Compute the compactive effort or compaction energy for a soil sample compacted in a mold with a volume of 1/30 cubic foot which uses 4 layers to place soil in the mold and compacts each layer using a hammer with a weight of 10 lbs that is dropped 12 inches and uses 20 blows per layer. (2 pts) 2. Using the result from question 1 compare the compaction energy to the Modified Proctor compaction test and the Standard Proctor compaction test? (2 pts) 3. What does the zero-air-voids line represent? (2 pts) 4. Estimate the Maximum dry density for a soil having an optimum water content of 14 percent and a specific gravity of 2.65. (3 pts) 5. Describe the steps used to perform a sand cone density test. (4 pts) 6. Describe two things you can do to increase the dry density of a sample that was 3 percent dry of the optimum water content for a sample compacted at a standard compaction energy if you wanted to increase the dry density of the soil. (2 pts

Answer 1

5 question answer

SAND CONE DENSITY TEST PROCEDURE:

1. Fill the jar with a standard sand-a sand with known density and determine the weight of

the sand cone apparatus with the jar filled with send (W1). The American Society for Testing

and Materials

(ASTM) recommands Ottawa send as the standard

2. Determine the weight of sand to fill the cone (W21)

3. Excavate a small hole in the soil and determine the weight of the excavated soil (W3)

4 Determine the water content of the excavated soil(w )

5. Fill the hole with the standard and by inverting the sand cone apparatus over the hole and opening the valve

6. determine the weight of the sand cone apparatus with the remaining sand in the jar (W4)

7 Calculate the unit weight of the sol as follows

Weight of sand to fill hole=Ws= W1-(W2-W4)

Weight of hole= Ws/¥d