OBJECTIVE : Determining specific gravity of a soil sample for weight-volume relationship .

THEORY :The specific gravity ,Gs of a soil is the ratio between the unit masses of soil particles and water .Gs is useful for determining weight-volume relationships .

EQUIPMENT:The equipment for determination os specific gravity includes :

1.Volumetric flasks(100ml)

2.No.7 Sieve (2.36mm)

3.Rubber mortar and pastel

4.Vacuum pump

5.Distilled deaired water.

6.Thermometer

PROCEDURE: 1)Prepare a dry and clean the Volumetric flask and measure its weight.(W1)

2)Take a sample between 100g-120g of air-dried soil and place it into a mortar.Use the pastel to break the soil grains into pieces small to be tested to go into the flasks.

3)Put the soil sample into 2.36mm sieve and the sample passing through the sieve is to be used for the test .The mass for the sample to be tasted must be between 5-10g.

4)Put some of the soil into the volumetric flask and measure the weight.(W2)

5)pour the distilled deaired water into the flask until all soil is soaked .Place the flask into the desiccator vacuum.

6)Reduce the air pressure to 2cm mercury .Be careful so that the soil-water mixture does not boil.Remove the vacuum after all the air in the mixture is released .

7)Fill up the flask with distilled water and then place into the vacuum . Repeat step no.6

8)Measure the weight of the flask (W3).

9)Empty the flask and fill up with distilled water . Place it into the dessicator vacuum and repeat step no.6 .For measure the weight of the flask with the distilled water .(W4)record the temperature of the water during the test.

10)Repeat the test to calculate additional values of Gs until the values of Gs are within 2% of each other.

COMPUTATION:

Specific Gravity (Gs)Formula .

Gs = W2-W1 / (w4-w1)-(W3-w2)

For the correction of calculation based on the water temperature , the value of Gs obtained must be multiplied with the coefficient of temperature .

TABLE 2 :Coefficient of Temperature

Temperature Coefficient 4 1.0000 15 0.9999 20 0.9982 25 0.9971 30 0.9957 35 0.9941

RESULT :

Test No. 1 2 3Mass of empty flask,W1(g) 30 30 30

Mass of Flask + dry soil,W2 (g) 52 58 60

Mass of Flask + soil + water , W3 (g) 140 140 138

Mass of Flask + water , W4 (g) 128 130 130

Specific Gravity, Gs 2.75 0.667 2.143

Average value of Gs 1.853 0 0

Coefficient of Temperature (a) 0.9925 0.9957 0.9925

Final Specific Gravity of soil, Gs

DISSCUSSION

As can be seen, the change due to the correction factor is minimal, due to the fact that _ isonly one one-thousandth different from 1.000. But the factor is noted, as it did change the valueslightly, and the values of Gs,_ are considered the more accurate value for this experiment. Thisbrings us to the evaluation of the final answers. Since it is already known that one sample issand, values from well-established tables can be used to compare with the calculations conductedhere. Sand typically has a specific gravity of 2.65 to 2.67. The value found here is exactly whereit is expected to be and it can be confirmed with much certainty that the sample produced atthe beginning of the experiment was indeed some kind of sand. The specific gravity of Sample 1ended up being 2.700.

CONCLUSION

Based on the accuracy of the test with sand, it can be assumed that this value is also veryaccurate; it is most likely accurate enough to wager a guess as to what type of soil it is. Unfortunately,a specific gravity of 2.7 is the upper extent of silty sand and also the lower extendof inorganic clay. Having minimal experience in dealing with soils on a scientific level, I cannotconfidently hypothesize as to which it is nor why. The color of the sample will probably make iteasier to decide between the two, but as of now, my experience does not allow me to pick whichtype of soil it could be. Future tests on this sample will be done which will allow me to identifythe soil. Fortunately, this experiment has narrowed the choices, assuming that there was as littleerror in this iteration of the experiment as there was with the sand.

REVIEW QUESTION :

1)Define Specific Gravity of soil .

Answer: Specific gravity of soil is the ratio of weight , in air of a given volume , of dry soil solids to the weight of equal volume of water at 4°c .

2)What are the typical values for the specific gravity for soils ?

Answer:The value of the grain specific gravity ranges from 2.65 for sands, 2.70 for silts , to 2.90 for clays on the average .

3)Can you apply the technique described in this section to measure the specific gravity of material lighter than water ?

Answer: Yes .

4)Why do we use vacuum while determining the specific gravity of soils ?

Answer:to determine the specific gravity of soil by using pycometer . Specific gravity is the ratio of the mass of unit volume of soil at stated temperature to the mass of the same volume of gas free distilled water at stated temperature.

5)What is the effect of water temperature on the determination of the specific gravity of soils ?

Answer: the temperature increase .

DEPARTMENT CIVIL ENGINEERINGPROGRAM DIPLOMA IN CIVIL ENGINEERINGCOURSE CODE & NAME CC304 GEOTECHNICS 1LECTURER’S NAME MDM. RENNY JOSEPHASSIGNMENT TITLE DETERMINATION OF SPECIFIC GRAVITYSECTION DKA 3DNAME (group c) ASRIL.BIN.M.ARIF 07DKA11F2177

MAZRIN .BIN.MANGSURI 07DKA11F2205HAMKA BIN MUSTAMIN 07DKA11F2215