Introduction
Field density testing is significant for assessing the soil properties of a site identified for a project. The assessment of soil property done through field density testing is aimed a verifying that the soil contained the required properties for the type of project to be constructed at the identified site (Thiers and Donovan 45). This lab uses the Sand Cone Method to verify the compaction of fill material and determine if the soil meet the required compaction with a design unit weight of 2,000 kg/m3. The aim of the experiment was to determine the dry unit weight, to determine the moisture content using the speedy moisture tester, to determine the unconfined compressive strength and to determine the shear stress of the surface soil using a pocket Torvane.
Method
The following materials were used in the lab; sand cone device, metal funnel, sand cone base plate, small excavation tool, Aluminum dish, Sand (Gs= 2.65), Pocket Torvane Device, balance beam and weights and pocket penetrometer.
The proper working of the device was confirmed and was securely fitted to the base plate. The sand cone was filled with the required sand and the initial weight (Wsci) was obtained and recorded. The evaporating dish was weighted and recorded (Wevp). The sampling location was determined and the base plate placed over the sampling site. A sampling hole was dug of approximately 1-1.5 inches in depth and 2-3 inches in diameter on the sampling site. The soil removed from the hole was gathered using the evaporating dish including the loosened fragments. The sand cone device was carefully place into the base plate. The valve was open to allow the sand fill the hole, cone and the base plate. The valve was closed and the final weight of the sand cone device (Wscr) was obtained after the sand stopped flowing into the cone. The weight of the soil removed from the test hole (Ws) was determined. The volume of the test hole (Vh) was then determined using equation.
Result
The volume of the test hole was determined using the equation and was obtained to be 67478.7392. On the other hand, the shear stress was determined to be 0.3 tons/ft^2 whole the unconfined compressive strength was determined to be 3 tons/ft^2. The dry unit weight was obtained to be 0.01438295. Using the dry unit weight and the volume, the unit weight can be determined to be 1.3x10-8 g/cm3.
Discussion
The soil field density test was conducted so as to determine whether the soil meets the required compaction of design unit weight of 2000 kg/m3. The test conducted obtained the dry unit weight to be 0.01438295. The unit weight was determined to be 1.3x10-8 g/cm3. This is below the required unit weight of 2000 kg/m3. As a consequence, the soil does not meet the required level of the compaction. It is recommended to avoid construction on the identified site since it does not meet the requirement of the design. Apart from sand cone method, there are other different methods for testing field density, both destructive and non-destructive. The test is significant since it help in avoiding unwanted disasters during or after construction. Destructive methods for testing field density involve the testing, evaluating and inspecting materials but are destructive to the test equipment (Thiers and Donovan 35). On the other hand, nondestructive methods do not include the destruction of the test material. Sand replacement method is an example of nondestructive method for testing field density.
Conclusion
Field density testing is significant for determining the properties of soil so as to meet the required standards for the design. The field density test done using sand cone method is simple as compared to other methods. The results obtained helped in the determination of the level of compaction of the soil. The required level of compaction was not attained by the test.
Appendix
Sand hole calculation
Vh= {(Wsci-Wscf)/ Ysand}- Vc
Y= Ws/Vh
Works Cited
Thiers, G. R., and Donovan, T. D.. "Field density, gradation, and triaxial testing of large-size
rockfill for little blue run dam." Laboratory shear strength of soil. ASTM International,
1981.
