Laboratory Test and Preparation of Report Use of Equipment
Laboratory Test and Preparation of Report Use of Equipment
Laboratory Test and Preparation of Report Use of Equipment
Laboratory equipment is never cheap. For accurate experimental results, the equipment should be properly maintained. The calibration of certain equipment, such as balances and proven rings, should be checked from time to time. It is always necessary to see that all equipment is clean before and after use. Better results will be obtained when the equipment being used is clean, so always maintain the equipment as if it were your own.
Report Preparation
In the classroom laboratory, most experiments described herein will probably be conducted in small groups. However, the laboratory report should be written by each student individually. This is one way for students to improve their technical writing skills. Each report should contain: 1. Cover page This page should include the title of the experiment, name and date on which the experiment was performed. (see example) 2. Following the cover page, the items listed below should be included in the body of the report; Objective(s) of the experiment Theory Equipment used A schematic diagram of the main equipment used A brief description of the test procedure 3. Results This should include the data sheet(s), sample calculation(s), and the required graph(s). 4. Graphs and Tables Graphs should be made as large as possible, and they should be properly labeled. Always give the units. 5. Conclusion(s) A discussion of the accuracy of the test procedure should be included in the conclusion, along with any possible sources of the error. 6. Bibliography and/or Reference.
Report Writing
A soil report should follow good technical report writing form, including the citing of any references used. Do not use the first person (I, me, we, our, etc.) in writing a technical report. Do not write such statements as, I found that or My group found, in stead use It was found that Use correct spelling, when in doubt, consult the dictionary.
CIVL 351 Soil Mechanics I Laboratory Test Laboratory #1: Field Identification of Soil and Sieve Analysis Objectives Part 1: Field Identification of Soil (a) To identify the classification of the soil by its size, colour and hardness. (b) To classify silt and clay by dilatancy test. Part 2: Sieve Analysis To obtain the grain size distribution and grading characteristics of the soil particles in a given soil sample. Part 1: Visual Classification of Granular Soils Several soil types found in the area will be available for your visual classification. 1.For each of the sample approximate the percentages of sand and gravels adding to about 100%. 2. Describe the sample be including: a. Color b. Gradation c. Soil subdivisions d. Presence of fines e. Grain shape Visual Classification of silt and clay Base on dilatancy: Moisten the soil sufficiently to make it soft, but not sticky. Place this pat of soil in the open palm of one hand and tap the side of this hand sharply with the other hand; repeat this several times. Dilatancy is exhibited if, as a result of this tapping, a glossy film of water appears on the surface of the pat. If the pat is now pressed gently the water will disappear from the surface and the pat becomes stiff again. Very fine sands and inorganic silts exhibit marked dilatancy, whereas clays and medium-to-coarse sands do not. Part 2: Sieve Analysis Equipment: Standard brass sieves. Balance sensitive to 0.1g. Containers Sieve. Oven.
Procedure: 1. Collect a representative dry sample of approximately 500g. 2. Determine the mass of your sample accurately to 0.1g. Record as W. 3. Prepare a stack of sieves. A sieve with a larger opening is placed above a sieve with smaller openings. The sieve at the bottom should be No.200. A bottom pan should be placed under sieve No.200. Generally the sieves used in a stack are No.4, 10, 20, 40, 60, 100, 200 ; however, more sieves can be placed in between. 4. Pour the soil prepared in step 2 into the stack of sieves from the top. 5. Place the cover on the top of the sieves. 6. Run the stack of sieves through the sieve shaker for about 5 minutes. 7. Stop the sieve shaker and remove the stack of sieves. 8. Weigh the amount of soil retained on each sieve and the bottom pan. Record as W1. 9. Calculate the total weight of soil retained on all sieves. The percentage loss during sieve analysis=(W-W1)/W*100 and must be less than 2% in order to validate the test. Results: 1.Describe the soil using the USCS system. USCS for coarse grained soils Coarse grained means that greater than 50% is retained on the No.200 sieve. For coarse grained soils: Determine if it is sand or gravel. If greater than 50% is retained on No.4 sieve then it is gravel (G), if greater than 50% passes No.4 sieve then it is sand (S). Then, a) Determine if it has appreciable fines. If greater than 12% passes No.200 sieve then classify as GM, GC, SM, SC depending on if it is sand or gravel and if the fines are silt (M) or clay (C). b) If there are not many fines, then look at the gradation. If it is well graded then classify as GW or SW and if it is poorly graded then classify as GP or SP. 2. Plot a Grain size distribution curve for the sieving test. 3. From the graph, find the coefficients of uniformity Cu and curvature Cc from D10 , D30 , D60 , the grain size corresponding to 10, 30, and 60% weight finer. Discussion Questions: 1. What is the purpose of particle size distribution? 2. Under what conditions should you use wet sieving analysis instead of dry sieving? 3. On what range of particle size does the sieve analysis apply 4. Is it possible to carry out a sieve analysis on a sample of clay?
Sieve number
Mass Retained(g)
% Retained
% Cumulative
% Passing
Liquid limit-Cone-penetration Method 1. Take a sample of about 300 g from the soil paste and place it on the glass plate. 2. Mix the paste and push a portion of the mixed soil into the cup with a palette knife. 3. Place the cup under the center of the cone. 4. Gradually lower the stem until the tip of the cone is exactly in contact with the surface of the sample. 5. Take the reading of the point on the gauge to 0.1 mm. This is the first reading. (R1) 6. Adjust the automatic release and locking device. 7. Press the start button. 8. After the 5 sec. countdown finished, take a second reading to 0.1 mm (R2) 9. Record the difference between the two readings (R2-R1). This is the first cone penetration. 1. 10 Lift out the cone and clean it carefully to avoid scratching. 10. Take a moisture content sample of about 10 g from the area penetrated by the cone and determine the moisture content. 11. Repeat at least three more times using the same sample of soil to which further increments of distilled water (about 4- 5cc) have been added. Proceed from the drier to the wetter condition of the soil. The amount of water added shall be such that a range of penetration values of approximately 15 mm to 25 mm is covered by the four or more test runs and is evenly distributed. Part2: Determination of PL Equipment 1. A flat glass plate, smooth and free from scratches, on which threads are rolled. 2. Two palette knives or spatulas. 3. Apparatus for the moisture content determination. 4. A length of rods, 6 mm and 3 mm in diameter and about 100 mm long. Plastic limit 1. Put approximately 20g of a representative, dry sample passing the No.40 sieve, into a dish. 2. Add water from the plastic squeeze bottle to the soil and mix thoroughly. 3. Determine the mass of a moisture can and record it ( W1 ). 4. From the moist sample, prepare several ellipsoidal-shaped soil masses by squeezing the soil with your fingers. 5. Take one of the ellipsoidal-shaped soil masses and roll it on a ground glass plate using the palm of your hand. 6. When the thread that is being rolled reached1/8 in (3mm) in diameter (compare with the glass rod at your station), break it up into several small pieces and squeeze it with your fingers to form an ellipsoidal mass again. 7. Repeat steps 5 and 6 until the thread crumbles into several pieces when it reaches a diameter of 1/8 in. It is possible that a thread may crumble at a larger diameter
during the rolling process, whereas it did not crumble at the same diameter during the immediately previous rolling. 8. Collect the small crumbled pieces in the moisture can and cover the can. 9. Take the other ellipsoidal soil masses formed in step 4 and repeat steps 5 to 8 until you have approximately 20g of wet soil. 10. Determine the mass of the moisture can plus wet soil ( W2 ). 11. Dry the soil in the can and determine the mass of the can plus dry soil ( W3 ). 12. Repeat steps 4 to 11 two more times. Calculations: 1. Determine the plastic limit from: W W3 PL = 2 W3 W1 2. Determine the plasticity index from: PI = LL PL Discussion Questions 1. What are the definitions of liquid and plastic limits? Are these definitions based on theoretical or empirical concepts? 2. Is it possible for a soil to have a liquid limit and a plasticity index (PI) both equal to 30%? Why? 3. What is the activity of clays? What is it used for?
Test No Container No
Mass of wet soil + container (m2) Mass of dry soil + container (m3) Mass of container (m1) Mass of moisture (m2 m3) Mass of dry soil (m3-m1) Moisture content=(m2-m3)/(m3-m1) g g g g g %
Average
Test No Initial dial gauge reading R1 mm Final dial gauge reading R2 mm Penetration (R2 R1) mm Container No
Mass of wet soil + container (m2) Mass of dry soil + container (m3) Mass of container (m1) Mass of moisture (m2 m3) Mass of dry soil (m3-m1) Moisture content=(m2-m3)/(m3-m1)
g g g g g %
Mass of wet soil + container (m2) Mass of dry soil + container (m3) Mass of container (m1) Mass of moisture (m2 m3) Mass of dry soil (m3-m1) Moisture content=(m2-m3)/(m3-m1)
where h is the head difference- use the difference between standpipes 1 and 3 for your calculations. The value of k is usually given for a test temperature of water at 20 o C. So to calculate
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k 20o C = k T oC
C C
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where the ratio of viscosities can be obtained from Table1. Questions: 1. Plot the differences in total heads ( h12 , h2 3 ) versus flow rate. Determine the coefficient of permeability (cm/sec) of the sand specimen. Comment on any nonlinearity observed from the plot. 2. Plot the elevation head, pore pressure head, and total head (x-axis) along the height of the chamber (y-axis) at quick sand conditions. Also, include the hydrostatic head (when no seepage takes place) and comment on the effect of seepage on pore pressure. 3. Calculate the hydraulic gradient required for occurrence of quick sand and compare the value with that observed in the laboratory. Constant Head Permeability Test Length of specimen, L = ________cm Diameter of specimen, D = ________cm Area of specimen, A = ________ cm 2 Volume of specimen, V = ________ cm 3 Specific Gravity, Gs = ________ Void ratio, e = _______ Initial conditions Standpipe 1 2 3 Elevation head, z _________ _________ _________
T C 20 C
O O
15 16 17 18 19 20 21 22 23 24 25 26
1.135 1.106 1.077 1.051 1.025 1.000 0.976 0.953 0.931 0.910 0.889 0.869
Test No
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Mass of water collected, M w (g) Temperature of water, (T O C ) Time of collection, t (s) Average flow, Q( cm 3 ) Pressure head Standpipe 1 Standpipe 2 Standpipe 3 Head difference (cm) Permeability, k (cm/sec) Average k = _______________cm/sec k 20 C = ________________cm/sec
o
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Part2. Compaction Equipment Compaction Mold. Drop hammer. Sample extruder. Metal straightedge. Mixing tools. Procedure: 1. Record the details about the weight of hammer and hammer drop which will be given in the laboratory. 2. Obtain about 3800g of dry soil. Break all lumps in the soil. 3. Determine the volume of the compaction mold by measuring its height and diameter. 4. Determine the mass of the compaction mold plus base plate (do not include the collar extension) ( W1 ). 5. Estimate the amount of water to be added to reach the desired water content which is about 4-5% below the optimum moisture content (OMC). The OMC will be given in the lab. Mix the water and soil thoroughly. 6. Attach the collar extension to the compaction mold. 7. Place the moist soil into the mold in three equal layers. Each layer should be compacted uniformly using the Standard Proctor hammer 25 times before the next layer of loose soil is added. Note: The layers of loose soil that are being placed into the mold should be such that at the end of the three layer compaction, the soil should extend slightly above the top of the rim of the compaction mold. 8. Remove the collar from the mold. Be careful not to break off ant of the compacted soil inside the mold while removing the collar. Note: If the soil breaks off below the rim, or if the last layer of compacted soil is not above the rim, then you must redo the compaction. 9. Using a straight edge, trim the excess soil above the mold. Now the top of the compacted soil will be even with the top of the mold. 10. Determine the weight of the mold + base plate + compacted moist soil ( W2 ). 11. Remove the base plate from the mold and extrude the soil from the mold. 12. From the moist soil extruded, take two samples from the center and determine the moisture content. To determine the moisture content, first weigh a cup ( W3 ), then determine the mass of the cup and wet soil ( W4 ), and the mass of the cup and dry soil ( W5 ), to calculate the moisture content. Take the average of the two moisture contents. 13. Break the rest of the compacted soil by hand down to its original size in the tray. Add more water to increase the water content of the soil by 2% based on the original soil weight. 14. Carefully remix the soil and repeat steps 6 to 13 until the mass of the mold+ base plate+ moist soil ( W2 ) begins to decrease. Continue the test until at least two successive down readings have been obtained.
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Questions: 1. What is the optimum water content and the maximum dry unit weight? 2. Plot the zero air voids (ZAV) line (i.e. S r =100%) on your graph. Show a sample of your calculation. 3. Explain why no portion of your compaction curve should plot to the right (i.e cross) the ZAV line.
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Compact Dry Density Determination Volume of mould (V) _____________________cm3 Test number Mass of mould + compact specimen (m1) g Mass of mould (m2)g Mass of compact specimen (m1 m2) g Bulk Density = (m1 m2)/V Mg/m3 Dry Density = 100 /(100 + w) Mg/m3 Moisture Content Determination Container number Mass of wet soil+ container(m3) g Mass of dry soil + container (m4) g Mass of container (m5) g Mass of moisture (m3 m4) g Mass of dry soil (m4 m5) g Moisture Content w = (m3-m4)/(m4-m5)100 %
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