Engineering Report Example

Determination of Field Unit Weight of Compaction by Sand Cone Method.

Objective of this experiment is to determine Field Unit Weight of Compaction by Sand Cone Method.

Description of Soil Samples:

The soil use in the lab experiment was Ottawa sand.
Description of Test Methodology:
At first dry unit weight of 20-30 Ottawa sand was determined by using Proctor compaction mold and a spoon filling it with the sand. Sand was then poured into mold without any vibration or other means of compaction. When the mold is full, the top of mold was struck off with steel straight edge. The weight of sand (W1) was determined. In the next step, the cone was calibrated to determine weight of Ottawa sand. One-gallon bottle was filled with Ottawa sand and the weight of bottle +cone + sand was determined. Then the valve of cone attached to the bottle was closed. After that the base plate was placed on a flat surface and the bottle with the cone was turned upside down. After this, the cone valve was opened. Sand flowed out of bottle and gradually filled the cone. After closing the cone valve the bottle and cone combination was removed from the base plate, its weight (W3) was determined. The weight of gallon can without the cap was also determined. Before proceeding to the field, one-gallon bottle was filled with sand and weight of bottle + cone + sand (W5) was determined after closing the valve of the cone. In the first activity of the field, base plate was placed on a level ground in the field and under the center hole of the base plate, a hole was dug in the ground using the digging tools. After removing all loose soil from the hole gallon can was put in it. Then cap was closed tightly so that moisture might not enter. In the next step, the gallon bottle filled with sand was turned upside down and placed it on center of base plate. Opening the valve of cone sand was allowed to flow from the bottle to fill the hole in the ground and cone. When the flow of sand from the bottle stopped, the valve of cone was closed and removed. The weight (W6) of gallon can + moist soil from the field (without cap) was determined. The weight (W7) of bottle + can + sand after use was also determined. Finally the gallon can with moist soil was put in the oven to dry to a constant weight and weight (W8) of can + oven-dry soil was determined.

Test Results:

Calibration of Unit Weight of Ottawa Sand
Weight of sand in the mold, W1 = 12.3215 lb
Weight of mold = 8.84444 lb
Volume of mold, V1 = 1/30 ft^3
γ d (sand) = W1/V1 = 102.648 lb/ft^3

Calibration Cone:

Weight of bottle + cone + sand (before use), W2 = 14.671 lb
Weight of bottle + cone + sand (after use), W3 = 10.944 lb
Weight of sand to fill the cone, Wc =W2-W3 = 3.677 lb

Results from Field Tests:

Weight of bottle + cone + sand (before use), W5 = 16.133 lb
Weight of bottle + cone + sand (after use), W7 = 4.744 lb
Volume of hole, (W5-W7-Wc)/ γ d (sand) = 0.0254 ft^3
Weight of gallon can, W4 = 0.7314 lb
Weight of can + moist soil, W6 = 2.454 lb
Weight of can + dry soil, W8 =2.6174 lb
Weight of moist soil, W6-W4 = 2.2276 lb
Moist unit weight of soil in field, γ = (W6-W4) γ d (sand) / (W5- W7 – Wc) = 85.8473 lb/ft^3
Moisture content in the field, w (%) = [W6 -W8/ W8 –W4] x 100 = 18.08 %
Dry unit weight in the field, γ d = γ /( 1 + w%/100) = 119.78

Discussion:

Conclusion:
The experiment was carried out safely and successfully. By carrying out this experiment the procedure to find out Field Unit Weight of Compaction by Sand Cone Method was gained. An idea about dry unit of soil as well as the relation between dry unit weight and compaction were also achieved. All the purposes of the experiment were met without any significant errors and here lies the success of the experiment.

Appendix:

Raw data sheet: