SOIL COMPACTION TEST
Compaction is the procedure of soil densification by lessening the voids inside the dirt example by pressing soil particles all the more firmly together by mechanical means in this way expanding the dry thickness. The level of compaction of a given soil is estimated as far as the dry thickness, which is most extreme at the ideal water content.
A curve is drawn between the water content and the dry thickness to get the greatest dry thickness and the ideal water content.
Be that as it may, this procedure must not be mistaken for union, where water is pressed out under the activity of a nonstop static load.
Densification is the conspicuous impact of this soil compaction, i.e. a unit weight increment prompting the gathering of a dirt mass with controlled building properties.
We will go up against the "Customary" compaction test, which varies from the "Altered" compaction test by the span of shape, Load by rammer and number of blows and compacting layers. The previous has a shape size of 1000cm3, rammer heap of 2.5kg and 27 blows in three (3) layers each. While, the adjusted has a greater form estimate, rammer heap of around 4.7kg and 62 blows in five (5) layers each.
AIM S/OBJECTIVES
The compaction test is aimed at determining the Maximum Dry Density and Optimum Moisture Content of soils at specific conditions of use.
Soil knowledge is important in civil engineering as Cuts and Fills are inevitable in the construction processes, which includes but not limited to: construction of transportation routes, erection of structures, e.t.c
1. Construction of transportation routes (sub-base for road, railway or airfield runway)
2. Made-up ground for erection of structures
3. Refilling of excavation, or void adjacent to structures (such as behind a retaining wall)
APPARATUS/DIAGRAMS
The following apparatus were used as specified to carry out the compaction test on the soil sample:
APPARATUS/EQUIPMENT SPECIFICATION
1 Cylindrical Metal Mould and removable extension collar Dia(in) = 10.5cm; Height = 11.55cm
Total volume = 1000cm3
2 Metal Rammer Dia(face) = 5cm; Weight(face) = 2.5kg
Height(dropping) = 30cm
3 Measuring cylinder Volume = 1000mL
4 Large Metal tray About 60cm x 50cm x 8cm
5 Weigh Balance 10kg capacity, reading to 1g
6 Jacking Apparatus Easy to use, for extracting compacted materials from mould
7 Small cutting tools: palette knife; scoop or garden trowel Length: 30cm
8 Drying Oven Temperature: 105-110°C
PROCEDURES
1. I weighed the mould body plus (+) base to the nearest 1g, recorded as M1 in Table 1 below
2. I measured the internal diameter (Din) and height of mould (H) using a vernier caliper and determined the volume of the mould, which is recorded in Table 1
3. I weighed a bulk sample of soil (W1), about 3kg
4. I riffled the bulk sample of about 3kg to obtain a representative sample and place in a mixing pan (head pan)
5. I calculated 3% of the soil sample which is 90grams (90mL) and evenly sprinkled on the soil sample
6. The moist soil sample was thoroughly mixed using the palette knife and then the use of hand
7. I assembled the based and placed it on a solid structure (a concrete floor)
8. I filled the mould and compacted the soil in three successive layers of 27 blows per layer as follows:
i- I added loose soil into the mould so that it is about half-filled
ii- I placed a second approximately equal layer of soil in the mould, and compacted with evenly
distributed 27 blows as of before
iii- The extension collar is placed and the third layer of the loose soil is added even unto the
collar and compacted with evenly 27 blows as of before
9. The extension collar was carefully removed while the excess soil was trimmed off and leveled of to the top of the mould
10. I weighed the compacted soil plus (+) mould and base after removing the spill or excess soil from the mould body, recorded as (M2) in Table 1 below
11. Two representative sample (Top layer and bottom layer) of the soil was taken from the mould into the moisture content cans for the measuring moisture content
12. The soil was removed from the mould back into the mixing pan
13. I broke up the material in the pan and mixed with the remainder of the prepared sample. I added an increment of water, approximately 3%, 90mL of water to 3kg of the soil.
14. I repeated steps 5 to 13 for each increment of water added, until six (6) compactions were made.
15. The sample remains were discarded.
DATA AND CALCULATION
Weight of Mould plus(+) Base, (M1)
Mould volume, (V) 3
Mass of sand bulk sample, (W1) 300grams
Compactio n: Mass (can) Mass(can + wet soil) Mass(wet) Mass(can + dry soil) Mass(dry)
1 4A = 23g
4AB = 24g 109g
112g 86g
88g 103g
106g 80g
82g
2 E9 = 18g
D9 = 17g 83g
76g 65g
49g 79g
73g 61g
46g
3 2A = 24g
T2 = 18g 142g
109g 118g
91g 132g
99g 108g
81g
4 H3 = 17g
M3= 12g 117g
103g 100g
91g 105g
94g 88g
82g
5 P2= 25g
P12 = 21g 110g
147g 85g
126g 102g
128g 77g
107g
6 E8 = 22g
H3 = 23g 165g
159g 143g
136g 140g
137g 118g
114g
Compactio n: Moisture Content, w Average moisture content
l values
Table 1.b: Moisture content cans and their values
1 4A: (86 – 80) / 80 = 0.075
4AB: (88 – 82) / 82 = 0.04878 W = 0.06 89
2 E9: (65 – 61) / 61 = 0.06557
D9: (49 – 46) / 46 = 0.065 2
3 2A: (118 – 108) / 108 = 0.09259
T2: (91 – 81) / 81 = 0.1236 W = 0.1080
4 H3: (100 – 88) / 88 = 0.1364
M3: (90 – 82) / 82 = 0.09756
W = 0.1170
5 P2: (85 – 77) / 77 = 0.1039
P12: (126 – 107) / 107 = 0.1776 W = 0.14075
6 E8: (143 – 118) / 118 = 0.2119
H3: (136 – 114) / 114 = 0.193 W = 0.20245
CALCULATION
Moisture Content values
1stCompaction Test:
Mass of mould (+) compacted soil, M2 = 4435grams Moisture content, w = 0.06189 x 100% = 6.189%
Bulk Density, db = Mass of soil = M2 - M1 = 4435 - 2991 = 1444 g
Volume 1000cm3 1000cm3 1000cm3
Db = 1.444g/cm3
Dry Density, dd = Db = 1.444 = 1.444g/cm3 = 1.3598g/cm3
Mass of mould (+) soil, M2 = 4742grams
Moisture content, w = 0.06539 x 00% = 6.539%
Bulk Density, db = g
Dry Density, dd = 3
Dd = 1.644g/cm3
Dd = 1.792g/cm3
4th Compaction Test:
Mass of mould (+) soil, M2 = 4896grams
Moisture content, w = 0.1170 x 100% = 11.700%
Bulk Density, db = 4896 – 2991 = 1905g Db = 1.905g/cm3
1000cm3 1000cm3
Dry Density. Dd = 1.905 = 1.905g/cm3 = 1.7055g/cm3
Dd = 1.706g/cm3
5th Compaction Test:
1000cm
1 + 0.14075
Bulk Density, db = 4992 – 2991 = 2001g Db = 2.001g/cm3
1000cm3 1000cm3
Dry Density, dd = 2.001 = 2.001g/cm3 = 1.6641g/cm3
Compaction: Moisture Content, w Dry Density, Dd(g/cm3)
1 6. 89 1.360
2 6.539 1.644
3 10.800 1.792
4 11.700 1.706
5 14.075 1.670
6 20.245 1.664
From the graph above, The Optimum Moisture Content of 10.8% occurs at a dry density of
1.792g/cm3
Optimum Moisture Content (OMC) = 10.8%
Maximum Dry Density (M.Dd) = 1.792g/cm3
PRECAUTIONS
The following precautions were taken when carrying out the “Ordinary” Compaction Test, so as to obtain values of negligible error or error free values:
1. I used an accurate weigh balance, that can read to the nearest 1gram and it is not susceptible the varying temperatures.
2. I made sure the tested soil sample was a representative fraction of the soil to be tested.
3. I made sure the 27 blows as specified were evenly distributed over the area of the soil in the mould.
4. I made sure the rammer fell freely from an height of 300mm so as to exact the required force.
5. I ensure the soil taken into the moisture content can were true representative of the soil moisture content, taken from the top and bottom
OBSERVATION
While carrying out the “Ordinary” compaction Test, the following observations were made:
1. I observed that as water content of the soil increased, it became easier for the soil to be densely packed, thereby expelling the air in the voids.
2. I observed that as the water (moisture) content approached a level, Optimum Moisture Content, the soil was saturated and could not be further compacted to give a dense mass.
3. It is been observed that any further increment of water after the Optimum Moisture Level, there would be a separation between the soil particle causing a slide against one another and results in a lesser mass for the same volume of soil.
4. The maximum dry density of the soil corresponds to the Optimum Moisture Content, which describes the densest form for a particular soil when a specified load is applied.
ERROR
As experiment cannot be totally free from error, due to varying experimental conditions and factors, the error experienced in this experiment can be attributed to the following source:
1. Deterghjyte (systematic) errors: These are errors that can be determined and estimable.
- Uncertainty inherent in the measurement devices (hard to read scales).
- Weighing an overfilled mould above the level plane.
- Soil spills when compacting, reducing the total mass of soil sample.
- Poor Design of Experiment.
2. Indeterminate (Random) errors: These are errors whose magnitude and algebraic sum cannot be determined
- Natural variation in measurements.
- Resting on the experimenting table, which takes the weigh balance off stability, affecting the readings.
- Biased decision during the experiment.
- Eye inability to read the exact level of liquid(water) in the graduated cylinder.
CONCLUSION
According to the aim of the experiment and the data obtained, the following conclusions were made:
1. The Maximum Dry density of a soil sample is that densest form in which a soil can be packed under a specific load and a specific moisture content, called the “Optimum Moisture Content (OMC)”.
2. The Dry density of a soil sample would continue to increase under a specified load until it reaches its Optimum Moisture Content.
3. The Maximum Dry density of the soil sample is 1.792g/cm3 at 10.8% moisture content.
It is been noted that the maximum dry density of a soil sample needs to be determined for every project which involves filling and made-up grounds, so as to avoid disaster in the transportation routes and structures which are constructed on this platforms. This helps to know the maximum mass of soil that would contain a specific volume under a specified compacting load.
No comments:
Post a Comment