Aim 2
Introduction 2
Apparatus 2
Method 2
Results 4
Discussion 5
Other methods used to determine specific gravity 6
Conclusion 7
Work Cited 8
Appendix 9
Aim
Introduction
Specific gravity is the comparison ratio of the mass of a model to the one of an equal volume of the standard substance. Specific gravity is an intensive characteristic of material. The same property can be used for analysis of velocity and other aspects of engineering design. In this experiment, the specific gravity is the ratio of the mass of a unit volume of a given soil sample at a certain temperature to the mass of the same sample volume the distilled water free of gas at that temperature (Prakash et al. 54)
Apparatus
Distilled water
Funnel
500 ml volumetric flask
Three medium sized evaporating dishes
Plastic squeeze bottle
Balance
Drying oven
At least three types of sand
Method
The volumetric flask and evaporated dishes are weighed to obtain Wf and Wd respectively
The volumetric flask is then filled with water and weighed to obtain W1 and also ensuring that the bottom of the meniscus flashes with the volume mark on the neck of the flash.
A weight of between 50 to 100 grams of each of the three soil types is obtained.
An approximate of one-third of the water is poured into the volumetric flask and is followed by pouring of the first soil sample and refilling of the volumetric flask with water to the 500ml mark.
A vacuum is applied to the volumetric flask and the sample and periodically swirled to agitate the air content.
The water is refilled to 500ml mark.
When there are no more bubbles, and while making sure that the outside and the neck of the volumetric flask is dry, the sample in the volumetric flask is weighed to obtain W2.
The flask is then emptied by swirling the sample and putting the thumb on the opening, then inverted, and the sample is allowed to settle into the neck of the flask.
The settled sample is then slowly emptied into an evaporating dish and dried in the oven.
Steps 1-9 above are repeated for the other two samples of soils.
With the help of the instructor, the three dried soil samples are then weighed to obtain Ws
Results
Ww = (W1 + Ws) – W2 (1)
The weight of the water volume is equivalent to the volume of the sample.
Specific gravity is given by
Gs = WsWw= ρsρw= γsγw .. (2)
Where ρ=density of the material
γ=Unit weight of the material
For example, the specific gravity for the sand experiment trial 1 is:
254.36/212.2 = 1.19
Discussion
According to Joe Flow filter design, the denser material will not settle first. The idea will not work as intended. The appropriate design should ensure heavier material settling on top first. This means the gravel with a higher specific gravity should be on top, followed by anthracite and lastly sand at the bottom. This will ensure proper filtration from the denser material to the least sense material at the bottom.
Other methods used to determine specific gravity
Use of ratio of weights in the air and when fully submerged in water.
The solid material is weighed in the air and then weighed when fully submerged in water. The weight of solid in air divided by the weight of solid when immersed water is the specific gravity of the solid
Use of Pycnometer method. Uses solid particles of coarse and fine-grained sand, pycnometer and water.
Falling drop method
The method involves timing the timing of a falling of a body fluid having a predetermined size through an immiscible fluid for a definite distance.
Use of a hydrometer. The instrument gives the specific gravity of the liquid directly.
Bottle method.
The method uses specific gravity bottle. In this case, a flask with a pre-determined volume and temperature is first weighed and then filled with fluid whose specific gravity is to be determined and then weighed again. The difference in weight divided by the weight of equal volume of water is the specific gravity of the liquid.
Conclusion
The specific gravity of three soils samples involved processes of taking of measurements of the soils in wet and dry conditions. The relation of the weight of the dried sample to the weight of water volume equivalent to the volume of sample gave the specific gravity of the sample. The experiment was done three times for soil sample to improve on precision. The sand and anthracite have the least specific gravity and the gravel having the largest. In each trial, a close range of values was found depicting the high level of accuracy of experimental performance. In summary, the aim of the experiment was achieved.
Work Cited
"Methods Of Determining Specific Gravity Of Liquids". Journal of the Institute of Brewing 25.4 (2009): 209-210. Web.
Prakash, K. et al. "A Simplified Approach of Determining The Specific Gravity Of Soil Solids". Geotechnical and Geological Engineering 30.4 (2012): 1063-1067. Web.
Appendix
Readings
USACE EM_1110-2-1906, Appendix IV [3]
ASTM D854-14 [6]
