Geotechnical Engineering Laboratory Manual PDF

GEOTECHNICAL ENGINEERING LABORATORY MANUAL Unfortunately, soils are made by nature and not by man, and the products of nature are always complex… karl von TERZAGHI  CONTENTS No Name of Experiment...

GEOTECHNICAL ENGINEERING LABORATORY MANUAL Unfortunately, soils are made by nature and not by man, and the products of nature are always complex… karl von TERZAGHI  CONTENTS No Name of Experiment IS Code Reference Page 1 Moisture Content IS:2720(Part-2)-1973 3 ( Reaffirmed 2006) 2 Specific Gravity 5 Fine Grained Soil IS:2720(Part-3/Sec1,2)-1980 Coarse Grained Soil ( Reaffirmed 2002) Atterberg Limits 7 3 Liquid Limit IS:2720(Part-5)-1985 8 4 Plastic Limit ( Reaffirmed 2006) 14 5 Shrinkage Limit IS:2720(Part-6)-1972 16 ( Reaffirmed 2001) Field Density 6 Core Cutter Method IS:2720(Part-29)-1975 18 ( Reaffirmed 2006) 7 Sand Replacement Method IS:2720(Part-28)-1975 19 ( Reaffirmed 2006) 8 OMC & MDD By Light Compaction IS:2720(Part-7)-1980 22 ( Reaffirmed 2002) 9 Proctor’s Plasticity Needle Test 26 Grain Size Analysis 10 Mechanical Sieve Analysis IS:2720(Part-4)-1985 28 11 Hydrometer Analysis ( Reaffirmed 2006) 30 12 California Bearing Ratio ( CBR) Test IS:2720(Part-16)-1987 41 Un Soaked CBR Test ( Reaffirmed 2002) Soaked CBR Test 13 North Dakota Cone Test IS:2720(Part-32)-1970 44 14 Direct Shear Test IS:2720(Part-13)-1986 45 ( Reaffirmed 2002) 15 pH Value Of Soil IS:2720(Part-26)-1987 51 ( Reaffirmed 2002) Permeability Test 16 Constant Head Method IS:2720(Part-17)-1986 53 17 Variable Head Method ( Reaffirmed 2002) 56 18 Consolidation Test IS:2720(Part-15)-1986 59 (Reaffirmed 2002) 19 Unconfined Compressive Strength IS:2720(Part-10)-1973 62 ( Reaffirmed 2006) 20 Laboratory Vane Shear Test IS:2720(Part-30)-1980 66 ( Reaffirmed 2002) 21 Triaxial Shear Test IS:2720(Part-11)-1993 68 ( Reaffirmed 2002) 22 Free Swell Index IS:2720(Part-40)-1977 73 ( Reaffirmed 2002) 23 Standard Penetration Test IS:2131-1981 74 ( Reaffirmed 2002) 24 Relative Density or Density Index IS:2720(Part-14)-1983 76 ( Reaffirmed 2006) 25 Heavy Compaction Test IS:2720(Part-8)-1983 82 ( Reaffirmed 2006) 1  KARL VON TERZAGHI 1883-1963 Karl Terzaghi, (born Oct. 2, 1883, Prague—died Oct. 25, 1963, Winchester, Mass., U.S.), He studied mechanical engineering at the Technical University in Graz, graduating in 1904, then worked as an engineer for several years; he was awarded a doctorate in engineering by the same institution in 1911. After visiting the United States, he served in the Austrian Air Force during World War I, but in 1916 he accepted a position with the Imperial School of Engineers, Istanbul. When the war was over, he took a post (1918–25) with Robert College, a U.S. institution, also in Istanbul. Much research had been done on foundations, earth pressure, and stability of slopes, but Terzaghi set out to organize the results and, through research, to provide unifying concepts. The results were published in his most noted work, Erdbaumechanik (1925;Introduction to Soil Mechanics, 1943–44). In 1925 he went to the United States, where—as a member of the faculty of the Massachusetts Institute of Technology, Cambridge—he worked unceasingly for the acceptance of his ideas, serving also as consulting engineer for many construction projects. In 1929 he accepted the newly created chair of soil mechanics at Vienna Technical University. He returned to the United States in 1938 and served as professor of civil engineering at Harvard University from 1946 until his retirement in 1956. His consulting practice grew to encompass the world, including the chairmanship of the Board of Consultants of Egypt’s Aswān High Dam project until 1959. 2  MOISTURE CONTENT IS: 2720 (Part 2) – 1973 (Reaffirmed 2006) Aim: To determine the moisture content (water content) of a given soil sample. Theory and applications: A soil is an aggregate of soil particles having a porous structure. The pores may have water and/or air. The pores are also known as voids. If voids are fully filled with water, The soil is called saturated soil and if voids have only air, the soil is called dry. Moisture content is defined as the ratio of the mass/weight of water to the mass/weight of soil solids W = Ww / Ws Where, W = water content Ww = Weight/ mass of water Ws = Weight/ mass of soil solids (mass of oven dry soil) The mass of water used in the above expression is the mass of free pore water only. Hence for moisture content determination the soil samples are dried to the temperature at which only pore water is evaporated. This temperature was standardized 105 0 C to 1100 C. Soils having gypsum are dried at 600 C to 800 C. The quantity of soil sample needed for the determination of moisture content depends on the gradation and the maximum size of particles. Following quantities are recommended. Size of particles more than 90% passing Minimum quantity of soil specimen to be taken for test, Mass in g 0.425 mm IS Sieve 25 2 mm IS Sieve 50 4.75 mm IS Sieve 200 9.5 mm IS Sieve 300 19 mm IS Sieve 500 37.5 mm IS Sieve 1000 The methods to determine moisture content in the laboratory are oven-drying, pycnometer, infrared lamp, torsion balance moisture meter. The approximate methods are alcohol burning method and calcium carbide method. Applications: Moisture content plays an important role in understanding the behavior of fine grained soils. It is the moisture content which changes the soils from liquid state to plastic and solid states. Its value controls the shear strength and compressibility of soils. Compaction of soils in the field is also controlled by the quantity of water present. Densities of soils are directly influenced by its value and are used in calculating the Stability of slopes, bearing capacity of soils-foundation system, earth pressure behind the retaining walls and pressure due to overburden. The knowledge of determining the moisture content is helpful in many of the laboratory tests such as Atterberg’s limits, shears strength compaction and consolidation. 3 OVEN DRYING METHOD Apparatus 1. Containers 2. Balance (accuracy 0.04 percent of the weight of the soil taken for test). 3. Oven 4. Desiccators. Procedure 1. Clean, dry and weigh the container. 2. Take the required quantity of the soil specimen in the container and weigh. 3. Maintain the temperature of the oven between 105 0 C to 1100 C for normal soils and 600 C to 800 C for soils having loosely bound hydration water or/and Organic matter. Dry the sample in the oven till its mass becomes constant. In normal conditions the 4. sample is kept in the oven for not more than 24 hours. After drying remove the container from the oven. 5. Weigh the dry soil with the container. Precautions 1. The soil specimen should be loosely placed in the container. 2. Drier the soil, the greater shall be the quantity of soil taken. 3. Overheating should be avoided. 4. Dry soil sample should not be left in open before weighing. 5. Water content specimen should be discarded and not to be reused for any other tests. Observations and Calculations The moisture content is calculated as follows: W= Ww / Ws = [(W2-W3) / (W3-W1)] x 100 % Where W1 = mass of container with lid W2 = mass of container + wet soil W3 = mass of container + dry soil 4  SPECIFIC GRAVITY IS: 2720 (Part 3 / Sec 1) – 1980 (Reaffirmed 2002) Fine Grained Soils AIM: This test is done to determine the specific gravity of fine-grained soil by density bottle. Specific gravity is the ratio of the weight in air of a given volume of a material at a standard temperature to the weight in air of an equal volume of distilled water at the same stated temperature. Apparatus: i) Two density bottles of 250ml capacity along with stoppers ii) Constant temperature water bath (27.0 + 0.2oC) iii) Vacuum desiccator iv) Oven, capable of maintaining a temperature of 105 to 110 oC v) Weighing balance, with an accuracy of 0.001g PREPARATION OF SAMPLE The soil sample (50g for one sample- minimum 3 samples) should if necessary be ground to pass through a 2mm IS Sieve. The sample should be obtained by riffling and oven-dried at a temperature of 105 to 110oC. Procedure to Determine the Specific Gravity of Fine-Grained Soil i) The density bottle along with the stopper, should be dried at a temperature of 105 to 110oC, cooled in the desiccator and weighed to the nearest 0.01g (W1). ii)The sub-sample, which had been oven-dried should be transferred to the density bottle directly from the desiccator in which it was cooled. The bottles and contents together with the stopper should be weighed to the nearest 0.01g (W2). iii) Cover the soil with air-free distilled water from the glass wash bottle and leave for a period of 2 to 3hrs. for soaking. Add water to fill the bottle to about half. iv)Entrapped air can be removed by heating the density bottle on a water bath or a sand bath. v) Keep the bottle without the stopper in a vacuum desiccator for about 1 to 2hrs. until there is no further loss of air. vi) Gently stir the soil in the density bottle with a clean glass rod, carefully wash off the adhering particles from the rod with some drops of distilled water and see that no more soil particles are lost. vii) Repeat the process till no more air bubbles are observed in the soil-water mixture. viii) Observe the constant temperature in the bottle and record. ix) Insert the stopper in the density bottle, wipe and weigh(W 3). 5 x) Now empty the bottle, clean thoroughly and fill the density bottle with distilled water at the same temperature. Insert the stopper in the bottle, wipe dry from the outside and weigh (W 4 ). xi) Take at least two such observations for the same soil. REPORTING OF RESULTS The specific gravity G of the soil = (W 2 – W 1) / [(W 4-1)-(W 3-W 2)] The specific gravity should be calculated at a temperature of 27oC and reported to the nearest 0.01. If the room temperature is different from 27 oC, the following correction should be done:-G’ = kG where,G’ = Corrected specific gravity at 27oC k = [Relative density of water at room temperature]/ Relative density of water at 27 oC. A sample proforma for the record of the test results is given below. Relative density of water at various temperatures is taken from table here. Relative Density Water EXAMPLE S Description I II III No 1 Weight of bottle (W 1) in g 150 152 160 2 Bottle + Dry Soil (W 2) in g 200 202 210 3 Bottle + Soil + Water (W 3) in g 431.2 432.1 441 4 Bottle + Water (W 4) in g 400 401 410 5 Test Temperature in 0C 31 31 31 Calculation A Specific Gravity 2.66 2.65 2.63 G = (W 2 – W 1) / [(W 4-W1)-(W 3-W 2)] B Average G at 310C 2.65 C G at 270C G = 2.647 or say 2.65 Specific Gravity of distilled water Temp 0C Specific Gravity Temp 0C Specific Gravity 25 0.997074 34 0.994399 26 0.996813 35 0.994059 27 0.996542 36 0.993712 28 0.996262 37 0.993357 29 0.995974 38 0.992994 30 0.995676 39 0.992623 31 0.995369 40 0.992246 32 0.995034 33 0.994731 6  ATTERBERG LIMITS A M ATTERBERG Albert Mauritz Atterberg (March 19, 1846 – April 4, 1916) was aSwedish chemist and agricultural scientist who created the Atterberg limits that are commonly referred to by geotechnical engineers and engineering geologists today. A fine-grained soil can exist in any of several states; which state depends on the amount of water in the soil system. When water is added to a dry soil, each particle is covered with a film of adsorbed water. If the addition of water is continued, the thickness of the water film on a particle increases. Increasing the thickness of the water films permits the particles to slide past one another more easily. The behavior of the soil, therefore, is related to the amount of water in the system. Approximately sixty years ago, A. Atterberg defined the boundaries of four states in terms of "limits" as follows:  Liquid limit: The boundary between the liquid and plastic states;  Plastic limit: The boundary between the plastic and semi-solid states;  Shrinkage limit: The boundary between the semi-solid and solid states. 7  LIQUID LIMIT TEST IS: 2720 (PART 5) – 1985 (Reaffirmed 2006) MECHANICAL METHOD ARTHUR CASAGRANDE Arthur Casagrande was born in August 28, 1902 and educated in Austria. He immigrated to US in 1926. There he accepted a research assistantship with the Bureau of Public Roads. AIM: To determine the liquid limit of given soil sample by mechanical method THEORY AND TERMINOLOGY: Liquid limit is the water content corresponding to the boundary between liquid and plastic limit states of soil mass. At liquid limit the soil has such low shear strength (about 1.76 kN/m2 or 17.6 g/cm2) that it flows to close a groove of standard dimensions for a length of 12 mm when jarred 25 times using the standard liquid limit device. The liquid limit and plastic limit of soils are both dependent on the amount and type of clay in soil and form the basis for the soil classification system for cohesive soils based on plasticity test.it also gives the cohesion property of soil and the amount of capillary water which it can hold. Consistency Index(IC): Ratio of the liquid limit minus the natural water content to the plasticity index of the soil. Flow Index(If): The slope of the flow curve obtained from a liquid limit test ,expressed as a difference in water content at 10 blows and 100 blows. Liquidity Index (or water plasticity ratio)(IL): The ratio expressed as a percentage of natural water content of soil minus the plastic limit to its plasticity index. 8 Plasticity Index (IP): The Numerical difference between the liquid limit and plastic limit. Toughness Index (IT): The ratio of plasticity index to the flow index. APPARATUS: 1. Liquid limit device. 2. Grooving tool. 3. Balance of sensitivity of 0.01g. 4. Moisture tin. 5. Iron spatula. 6. Hot Air oven. 7. Porcelain basin. PROCEDURE: 1. Weight about 200 g of air dried soil passing through 425 micron IS Sieve. 2. Take the soil in a porcelain basin and add clear water till it becomes paste. Mix the soil thoroughly (certain soil require mixing up to 40 minutes). 3. Check and adjust the fall of the liquid limit device cup to exactly 1 cm, using the gauge on the handle of the grooving device. 4. Place the soil paste in the cup of liquid limit device and level it horizontal with lowest edge of the cup with spatula so that the maximum depth of soil in the cup is 1 cm. 5. Using standard grooving tool ,make a groove in the middle of the soil along the diameter , dividing the soil into two parts (use casagrande grooving tool for soils containing more clay and ASTM device for soils containing more silts). 6. Turn the handle of the liquid limit device at the rate of 2 revolutions per second, till the two parts of the soil in the cup join together i.e. the groove closes by 12 mm length. Ensure that the grooving closes by flow and not by slipping of soil on the surface of the cup. 7. Note the number of blows imparted to the cup. Taken about 20 g of moist soil from the centre of the groove in a moisture tin and determine its moisture content. 8. By altering (increasing) the water content of the soil and repeating the above operation obtain five or six sets of observation, for blows in the range of 15 to 35. 9. The test should always proceed from drier (more blows) to wetter(less blows) condition of the soil. Each time the soil is thoroughly mixed to ensure that the water content is uniform throughout the soil mix. 9 Liquid limit (wL): Tabulation Container Weight Weight of Weight of Number Moisture serial of container+ container+ of Blows Content No container wet soil dry soil (g) N w% g (g) A B C D E F=(C-D)/(D-B) 1 11.73 48.17 38.34 33 36.94 2 12.57 52.16 41.34 28 37.61 3 12.07 50.29 39.64 21 38.63 4 12.51 51.17 40.27 18 39.27 5 14.06 50.83 40.33 15 39.97 LIQUID LIMIT OF SOIL WL= 38 % 40 39 Moisture Content (%) 38 37 36 35 10 100 No of blows(N) Graph: Plot the results of the experiment on a semi log sheet. The percentage of moisture content are marked as ordinates on the arithmetic scale and corresponding number of blows are marked as abscissae on logarithmic scale. A straight line in drawn connecting these points (maximum point should in the straight line) and the line shall be extended to either end, so as to intersect the abscissae corresponding to 10 and 100 blows. This line is called flow curve. The slope of this line expressed as the difference in water content at 10 blows and 100 blows shall be reported as flow index. The flow index may be calculated from the following equations. 10 If = (w1-w2) / log10 (N2/N1) Where If- flow index w1- Moisture content in % at N1 blows. w2- Moisture content in % at N2 blows. REPORT OF RESULTS: The liquid limit & flow index should be reported to the nearest whole number. The history of soil sample, that is , natural state , air dried , oven dried or unknown, the method used for the test reported and the period of soaking allowed after mixing of water to the soil shall be reported. 11  LIQUID LIMIT TEST IS: 2720 (PART 5) – 1985 (Reaffirmed 2006) CONE PENETRATION METHOD AIM: Determination of liquid limit of given soil sample by cone penetration method. AAPPARATUS: 1. Cone penetrometer- it shall consist of a metallic cone with angle of 310 and 30.5 mm coned length. The rod should pass through two guides (to ensure vertical movement), fixed to the stand. Suitable provision shall be made for clamping the vertical rod at any desired height above the surface of the soil paste in the cup. 2. Cup- 50 mm diameter and 50 mm height. 3. Balance 4. Moisture tin 5. Oven PROCEDURE: 1. Take about 150 g of air dried soil passing through 425 micron IS Sieve. 2. Soak the soil sample with distilled water for 30 to 40 minutes in case of silt soil and in case of clay soil soaking may take up to 24 hours. 3. The wet soil paste shall then be transferred to the cylindrical cup of the cone penetrometer apparatus and leveled up to the top of the cup. 4. Adjust the cone point just to touch the surface of the soil paste in the cup and clamp zero indicators (holding the in position by the hand). 5. Release the cone and record the penetration in mm on scale after a lapse of 30 seconds time. 6. If the penetration is less than 20 mm, the wet soil in the cup shall be taken out and more water added and thoroughly mixed. 7. The test shall then be repeated again till a penetration between 20 mm to 30 mm is obtained. 8. The moisture content of wet soil in the penetration cone shall be determined taking at least three samples. CALCULATION: The liquid limit of the sample is determined by using the following relationship wL= w / 0.77 log10 x or, wL= w / 0.65 + 0.0175 x Where 12 wL= Liquid limit of the soil w = Moisture content of the soil corresponding to the penetration of x mm. x = Depth of penetration of cone in mm. REPORT OF RESULT: The liquid limit so obtained should be reported to the nearest whole number. The history of the soil sample, that is natural state, air drained oven dried, and the period of soaking allowed after mixing of water to the soil shall also be reported. 13  PLASTIC LIMIT IS: 2720(Part 5)-1985 (Reaffirmed 2006) OBJECTIVE Determination of the plastic limit of soil. EQUIPMENT & APPARATUS 1. Oven 2. Balance (0.01 g accuracy) 3. Sieve [425 micron] 4. Flat glass surface for rolling 5. PREPARATION SAMPLE After receiving the soil sample it is dried in air or in oven (maintained at a temperature of 600C). If clods are there in soil sample then it is broken with the help of wooden mallet. The soil passing 425 micron sieve is used in this test. PROCEDURE 1. A soil sample of 40 gm. passing 425 micron IS sieve is to be taken. 2. It is to be mixed with distilled water thoroughly in the evaporating dish till the soil mass becomes plastic enough to be easily moulded with fingers. 3. It is to be allowed to season for sufficient time, to allow water to permeate throughout the soil mass. 4. 8 g of the above plastic mass is to be taken and a ball is formed. Then, it is to be rolled between fingers and glass plate with just sufficient pressure to roll the mass into a thread of uniform diameter throughout its length. The rate of rolling shall be between 60 and 90 stokes per minute. 5. The rolling is to be continued till the thread becomes 3 mm. in diameter. 6. The soil is then kneaded together to a uniform mass and rolled again. 7. The process is to be continued until the thread crumbled with the diameter of 3 mm. 14  8. The pieces of the crumbled thread are to be collected in an air tight container for moisture content determination. REPORT The Plastic limit is to be determined for at least three portions of soil passing 425 micron IS sieve. The average of the results calculated to the nearest whole number is to be reported as the plastic limit of the soil. PRECAUTIONS  Soil used for plastic limit determination should not be oven dried prior to testing.  After mixing the water to the soil sample , sufficient time should be given to permeate the water throughout the soil mass  Wet soil taken in the container for moisture content determination should not be left open in the air; the container with soil sample should either be placed in desiccators or immediately be weighed. Tabulation: Plastic limit (wP) container container container+ container+ w(%) No (g) wet soil dry soil (g) (g) 1 12.1 21.83 19.7 28.03 2 12.44 21.32 19.41 27.40 3 12.29 22.46 20.29 27.13 Average 27.52 wp 28 % 15  SHRINKAGE LIMIT TEST IS: 2720 (PART 6) – 1972 (Reaffirmed 2001) NEED AND SCOPE As the soil loses moisture, either in its natural environment, or by artificial means in laboratory it changes from liquid state to plastic state to semi-solid state and then to solid state. The volume is also reduced by the decrease in water content. But, at a particular limit the moisture reduction causes no further volume change. A shrinkage limit test gives a quantitative indication of how much moisture can change before any significant volume change and to also indication of change in volume. The shrinkage limit is useful in areas where soils undergo large volume changes when going through wet and dry cycles (e.g. earth dams) APPARATUS 1. Evaporating Dish of Porcelain 2. Spatula and Straight Edge 3. Balance-Sensitive to 0.01 g minimum. 4. Shrinkage Dish. Circular, porcelain or non-corroding metal dish 5. Glass cup. 50-55 mm in diameter and 25 mm in height 6. Glass plates. Two, 75x75 mm one plate of plain glass and the other prongs 7. Oven 8. Wash bottle containing distilled water 9. Mercury. PROCEDURE Preparation of soil paste 1. Take about 100 g of soil sample from a thoroughly mixed portion of the material passing through 425-µm I.S. sieve. Place about 30 g the above soil sample in the evaporating dish and thoroughly mixed with distilled water and make a creamy paste. (Use water content slightly higher than the liquid limit.) Filling the shrinkage dish 2. Coat the inside of the shrinkage dish with a thin layer of Vaseline to prevent the soil sticking to the dish. 3. Fill the dish in three layers by placing approximately 1/3 rd of the amount of wet soil with the help of spatula. Tap the dish gently on a firm base until the soil flows over the edges and no apparent air bubbles exist. Repeat this process for 2nd and 3rd layers also till the dish is completely filled with the wet soil. Strike off the excess soil and make the top of the dish smooth. Wipe off all the soil adhering to the outside of the dish. 4. Weigh immediately, the dish with wet soil and record the weight. 5. Air- dry the wet soil cake for 6 to 8 hrs, until the colour of the pat turns from dark to light. Then oven-dry the cake at 1050C to 1100C say about 12 to 16 hrs. 6. Remove the dried disk of the soil from oven. Cool it in a desiccator. Then obtain the weight of the dish with dry sample. 7. Determine the weight of the empty dish and record. 8. Determine the volume of shrinkage dish which is evidently equal to volume of the wet soil as follows. Place the shrinkage dish in an evaporating dish and fill the dish with mercury till it overflows slightly. Press it with plain glass plate firmly on its top to remove excess mercury. Pour the mercury from the shrinkage dish into a measuring 16  jar and find the shrinkage dish volume directly. Record this volume as the volume of wet soil pat. Volume of the Dry Soil Pat 9. Determine the volume of dry soil pat by removing the pat from the shrinkage dish and immersing it in the glass cup full of mercury in the following manner. Place the glass cup in a larger one and fill the glass cup to overflowing with mercury. Remove the excess mercury by covering the cup with glass plate with prongs and pressing it. See that no air bubbles are entrapped. Wipe out the outside of the glass cup to remove the adhering mercury. Then, place it in another larger dish, which is, clean and empty carefully. Place the dry soil pat on the mercury. It floats submerge it with the pronged glass plate which is again made flush with top of the cup. The mercury spills over into the larger plate. Pour the mercury that is displayed by the soil pat into the measuring jar and find the volume of the soil pat directly. TABULATION AND RESULTS S.No Determination No. 1 2 3 1 Wt. of container in g,W1 2 Wt. of container + wet soil pat in g,W 2 3 Wt. of container + dry soil pat in g,W 3 4 Wt. of oven dry soil pat, W 0 in g 5 Wt. of water in g 6 Moisture content (%), W 7 Volume of wet soil pat (V), in cm 8 Volume of dry soil pat (V0) in cm3 By mercury displacement method a. Weight of displaced mercury b. Specific gravity of the mercury Shrinkage limit (W S) = 9 [W - (V-V0) x ‫ץ‬w / W 0)] x 100 10 Shrinkage ratio (R) CAUTION : DO NOT TOUCH THE MERCURY WITH GOLD RINGS. 17  FIELD DENSITY (IN SITU DENSITY) OF SOIL CORE CUTTER METHOD IS: 2720 (Part 29) – 1975 (Reaffirmed 2006) APPARATUS 1. Cylindrical core cutter 2. Hammer. 3. Excavating tools, crow bar, Trowel. 4. Balance 5. Moisture can. 6. Straight edge. PROCEDURE 1. Clean the core cutter and dolly. Weight the core cutter (W 1) and determine its volume (V). Apply grease inside the core cutter. 2. Clear an area of about (45x45) cm2 size and trim off 10cm of top soil and make it level. 3. Drive the core cutter (with dolly fitted on top) with hammer to its full depth. Avoid overdriving by seeing the top level of the soil in the cutter through the air vent provided in the volley. 4. Dig out the core cutter with the help of crow bar and lift it carefully from the ground with the help of a trowel placed at the bottom of the cutter. Trim the top and bottom surface of the sample with a straight edge. 5. Determine the weight of the core cutter with soil (W 2). CALCULATION 1. Mass of Core Cutter W1(g) 2. Mass of Core + Soil, W 2(g) 3. Mass of wet soil (W 2-W1) 4. Mass of moisture tin(g) 5. Mass of moisture tin + wet soil (g) 6. Mass of moisture tin + dry soil (g) 7. Mass of Water = (5-6) 8. Mass of Dry soil = (6-4) 9. Moisture Content, W= (7/8) x 100 Result 10. Wet Density (γt) = (W 2-W 1) / V (g/cc) 11. Dry Density (γd)= γt / (1+w) g/cc 12. Void Ratio, e = (Gs γw )/ γt 13. Degree of Saturation ,S = (w.Gs /e) x 100 % 18  IN SITU DENSITY OF SOIL SAND REPLACEMENT METHOD IS: 2720 (Part 28) – 1975 (Reaffirmed 2006) Apparatus Special 1. Sand pouring cylinder 2. Trowel or bent spoon 3. Cylindrical calibrating container 4. Metal tray with hole (30 cm square with 10 cm hole in the centre) 5. Sand (clean oven dried, passing 1mm and retaining on 600 micron sieve) General 1. Balance (accuracy 1gm) 2. Balance (accuracy 0.01gm) 3. Oven 4. Glass plate (about 45 cm square) Background As we know density means weight per unit volume or in other words how much mass is being enclosed in a specific quantum of volume. We can easily determine the mass of soil by using the physical balance or digital balance, but the problem lies in finding the volume of the hole dug. This problem is solved with the help of a calibrated sand whose unit weight or density is already being determined and thus if we could determine how much weight of calibrated sand is going to rest in the dug hole we can find the volume of the hole by using following formula; Volume of dug hole = weight of soil in hole dug / unit weight of calibrated soil Procedure The standard procedure of this test is being divided in two parts in first part we will find the unit weight of the standard sand by calibration process described as follows; Calibration 1. Determine the internal volume (V) of the calibrating container by using dimensions. 2. Now fill the sand pouring cylinder with the sand (passing through 1 mm and retained on 600 micron sieve) to be calibrated within about 20 mm of its top left vacant and then determine the mass of the sand pouring cylinder along with sand and note it as w1. 19 3. Now place the sand pouring cylinder on top of calibrating cylinder of known volume and open the shutter to allow the sand to fall in to the cylinder after no more sand is falling close the shutter and determine the mass of the calibrating cylinder filled with sand and note it as W2 4. Now as we also have the weight of the sand in the conical portion of the sand pouring cylinder, we must subtract the weight of sand that can accumulate within that conical portion. For that take a flat glass plate and place the sand pouring cylinder. Open the shutter till no more sand falls and determine the mass of sand in the conical portion and note it as W3. 5. Now the weight of the sand in the calibrating cylinder is determined as Wa = W1 – W2 – W3 6. The bulk density of the sand is determined by dividing the mass of sand in the calibrating cylinder with the volume of the calibrating cylinder. Density of Sand γs = Wa / V Alternate method of calibration of sand Take the sand pouring cylinder with dry sand (passing through 1 mm and retained on 600 micron IS sieve), place it on the calibrating cylinder and open the shutter. Sand will be collected in the calibrating cylinder with a heap. Level the sand and Mass of calibrating cylinder + sand (M1) Mass of calibrating cylinder (M2) Volume of Calibrating Container, V (cm3) Density of Sand γs = (M1-M2) / V Determine the In situ Density of the soil Before going to field, once again fill the sand pouring cylinder with the calibrated sand and determine its mass as W4. 1. Prepare the area subject to test, level the top of the soil using the scrapper tool. 2. Place the metal tray on the flat surface, if required insert the nails into the small holes of the metal tray. 3. Trace the circular hole of the tray on the ground and excavate the soil carefully without losing any of the soil. Dig a hole of approximately 12-15 cm in the ground. 4. Collect all the excavated material in a metal container and clear the hole using a brush. 5. Determine the mass of this soil as weight of wet soil from hole Ww. 6. Place the cylinder directly over the excavated hole. Allow the sand to run out the cylinder by opening the shutter. Close the shutter when the hole is completely filled and no further movement of sand is observed. 7. Now weigh the remaining sand in the sand pouring cylinder and note it as W5. 8. Take a sample of the excavated soil in an air tight sampler for the determination of the moisture content. 9. Volume of the hole is determined by using the unit weight of the calibrated sand 20 already known; Observations and Calculations (Example) Volume of calibrating container = V cm3 = 1000 cm3 Weight of cylinder + sand (before pouring) , W1 g = 7400 g Mean weight of cylinder + sand (after pouring), W2 g = 5600 g Mean weight of sand in cone (of pouring cylinder), W3 g = 400 g Weight of sand to fill calibrating container Wa = w1 – w2 – w3 g = 1400 g Density of sand, γs = Wa / v = 1.40 g/cm3 Density of Soil The weight of sand ( Wb ) in g, required to fill the excavated hole shall be calculated from the following formula: Wb = W4 – W5 – W3 where W4 = weight of cylinder and sand before pouring into hole in g, W5 = weight of cylinder and sand after pouring into hole and cone in g, and W3 = mean weight of sand in cone in g. The bulk density of soil γb, shall be calculated from the following formula: γb = (Ww / Wb) x γs where Ww = weight of soil excavated from the hole in g, Wb = weight of sand required to fill the hole in g, and γ s = bulk density of sand in g/cm3. After determination of moisture content calculate the dry density of soil. Precaution 1. Care should be taken in excavating the hole to that it is not enlarged by levering the dibber against the side of the hole, as this will result in lower density being recorded. 2. No lose material should be left in the hole. 3. Initial height of sand in the pouring cylinder should be kept same during calibration and density determinations. 4. There should be no vibrations during this test. 5. Since dry density of soils varies from point to point, it is necessary to repeat the test at several point, it is necessary to repeat the test at several points and to average the result. 21  LIGHT COMPACTION TEST IS: 2720 (Part 7) – 1980, (Reaffirmed 2002) AIM: To determine the maximum dry density (M.D.D.) and optimum moisture content (O.M.C.) of a given soil sample using the standard proctor method. THEORY: This test determines the optimum amount of water be mixed with a soil in order to obtain maximum compaction for a given compaction effect. This will enable the field engineer to plan field compaction of the soil to a degree comparable to that obtained in the laboratory by suitably altering the effective lift or number of passes with the available roller. Maximum compaction leads to maximum dry density and hence the deformation and strength characteristics of the soil turn out to be best possible value. This test is based on the method given by R.R. Proctor (1933) and referred as to standard proctor test. This test is satisfactory for cohesive soil but does not lead itself well to the study of compaction characteristics of clean sands and gravel which are easily displaced when compacted with rammer. When high densities are warranted as in case of formation for airport runways higher compaction effort becomes necessary. For this modified proctor test is adopted. APPARATUS: 1. Standard proctor test apparatus. a. Cylindrical mould. b. Collar. c. Base plate. d. Rammer. 2. 4.75 mm IS sieve. 3. Glass measuring cylinder. 4. Iron spatula. 5. Balance & weight box. 6. Sample extractor. 7. Moisture tin. 8. Oven. 9. Desiccator. 10. Tray. 22  PROCEDURE: 1. Weight the empty mould (W m). Fix the mould to the base plate and attach the collar to the mould. Apply a thin layer of grease to the inside surface of mould & collar. 2. Take 2.4 Kg. of soil passing through 4.75 mm size sieve and add water to bring its moisture content to about 8% in case of silt soil and 14% in case of clayey soil. For uniformity this quantity of water is sprinkled on the soil and the soil is mixed thoroughly. 3. Keep the soil covered under an oil paper for 15 to 20 minutes to allow the soil for full maturation. 4. Divide the weight soil into three equal parts. Fill the mould with one part of the soil and compact it with 25 evenly distributed blows with the standard rammer. 5. Repeat this process for second & third parts of the soil taking precaution to scratch the top of the previously compacted layer with a spatula in order to avoid stratification and achieve homogeneity. 6. Remove the collar by rotating it and trim the top of the soil to flush with the top of the mould. 7. Detach the mould (with compacted soil in it) from the base plate. Take the weight of compacted soil along with the mould(W 1). 8. Extract the soil from the mould and take some wet soil from the core of compacted soil and determine the moisture content. 9. Repeat this procedure (5 to 6 times) by taking fresh soil sample and adding water to make the water content 2 to 4% more than the previous water content. TABULATION (STANDARD PROCTOR TEST) Tested by: - Date: Soil type: - 1 Test No. 1 2 3 4 5 6 2 Weight of empty mould (W m) gms. 3 Internal dia of mould (d) cm. 4 Height of mould (h) cm. 5 Volume of mould (V) = (π/4) d2h. C.C. 6 Weight of mould + compacted soil (W 1) gms. 7 Weight of compacted soil (W 1 – Wm) gms. 8 Wet density γt = (W 1-Wm) / V gm./C.C. 9 Container No. 10 Wt. of Container (X1) gms. 11 Wt. of Container + wet soil (X2) gms. 12 Wt. of Container + dry soil (X3) gms. 13 Wt. of dry soil (X3 – X1) gms. 14 Wt. of water (X2 – X3) gms. 23 15 Water content W% = (X2 – X3) / (X3 – X1) 16 Dry density γd = (γt) / (1 + ) gm./C.C. CALCULATION: Wet density = Moisture content % = x 100 Dry density (gms. /C.C) = Calculation of Zero Air Void Line: Zero air void line gives the relationship between dry density and moisture content when the degree of saturation is assumed to be 100%. It can be calculated by using the following formula: - γd = γw γd – Dry density corresponding to 100% saturation ( gm. / C.C.). G – Specific gravity of soil solids. W – Water content of soil (%). γw – unit weight of water (gm. / C.C.) GRAPHS: Draw the following graphs: - 1. A graph between moisture content and the corresponding dry density obtained from the compaction test. 2. A graph between the assumed water content and the corresponding dry densities calculated from the above formula. The curve is known as Zero Air Void Line. REPORT OF RESULT: The maximum dry density (MDD) in g/C.C should be reported to nearest 0.01. The optimum moisture (OMC %) is reported to nearest 0.2 for values below 5%, to the nearest 0.5 for values from 5 to 10 %, and to the nearest whole number for value exceeding 10 percent. 24 25  PROCTOR’S PLASTICITY NEEDLE TEST ASTMD- 1558 AIM: To determine the penetration resistance of a compacted soil with its moisture content and dry density. APPARATUS: The proctor’s static penetrometer with plasticity needle points, proctor’s compaction test apparatus etc. THEORY: In standard proctor compaction test it is observed that maximum dry density of a given soil is obtained only at a particular moisture content called the optimum moisture content and it is best to compact the soil in an embankment at this state for the most desirable structure effects. But in actual practice it is difficult to subject the soil in the embankment to moisture content determination at every stage. By simple penetration test the moisture content and density relationship of a soil could be studied in the field. The results obtained by the test in the laboratory could thus be used for effective compaction control in the field. PROCEDURE: 1. Select a suitable penetration needle and note down its cross sectional area and attach it to the penetrometer. 2. Push the penetrometer with penetration into the compacted soil mould at a speed of 12mm per second to a depth of 75mm. Record the maximum penetration resistance in (kg.) obtained during the above penetration. 3. Compute the penetration resistance per unit area (kg/cm2) corresponding to the moisture content of the soil. 4. Repeat the test for each trial of the light compaction / standard proctor test. Plot the penetration resistance (kg/cm2) versus corresponding moisture content (%) obtained from the compaction test on the already plotted moisture content versus dry density graph. 26 TABULATION (PROCTER’S PLASTICITY NEEDLE TEST) 1 Test No. 1 2 3 4 5 2 Area of plasticity needle (cm2) 3 Penetration resistance (Kg) 4 Penetration resistance per unit area (cm2) 5 Moisture content (%) GRAPH: Plot the graph between moisture content versus penetration resistance. 27  GRAIN SIZE ANALYSIS IS: 2720 (Part 4) – 1985 (Reaffirmed 2006) MECHANICAL SIEVE ANALYSIS OBJECTIVE For determination of particle size distribution of fine, coarse and all-in-aggregates by sieving. EQUIPMENT & APPARATUS:  Balance  Sieves ( 20, 10, 6.25, 4.75, 2, 1 mm, 600, 425, 300, 212, 150, 75 micron)  Sieve shaker PREPARATION SAMPLE After receiving the soil sample it is dried in air or in oven (maintained at a temperature of 600C). If clods are there in soil sample then it is broken with the help of wooden mallet. PROCEDURE 1. The sample is dried to constant mass in the oven at a temperature of 1100±50C. 2. Take 1000 g of dry soil (Quantity may vary according to the maximum size of the particle present in the soil mass). 3. Using a 75 micron IS sieve wash the soil to remove the fine particles present in soil. 4. After washing collect the wet soil mass retained on the sieve. 5. Put the wet soil in oven for 24 hours. 6. After the soil is dried, arrange all the sieves which are to be used in the analysis. 7. The oven dry sample is weighed and sieved successively on the appropriate sieves starting with largest. Each sieve is shaken for a period of not less than 2 minutes. 8. On completion of sieving the material retained on each sieve is weighed. CALCULATION The percent retained (%), Cumulative retained (%) & percent finer (%) is calculated. Percent retained on each sieve = Weight of retained sample in each sieve / Total weight of sample before washing. The cumulative percent retained is calculated by adding percent retained on each sieve as a cumulative procedure.The percent finer is calculated by subtracting the cumulative percent retained from 100 percent. REPORT The result of the sieve analysis is reported graphically on a semi log graph, taking sieve sizes on log scale and % finer in arithmetic scale. The observation is maintained in observation sheet. 28  Tabulation: SIEVE ANALYSIS, Mass of dry soil = 1000 g SIEVE MASS % CUM % % SIZE (mm) RETAINED(g) RETAINED RETAINED FINER 10 10 1 1 99 6.25 20 2 3 97 4.75 30 3 6 94 2 50 5 11 89 1 40 4 15 85 0.6 70 7 22 78 0.425 80 8 30 70 0.3 50 5 35 65 0.212 40 4 39 61 0.15 20 2 41 59 0.075 40 4 45 55 100 90 PERCENTAGE FINER 80 70 60 50 40 30 20 10 0 0.001 0.010 0.100 1.000 10.000 GRAINSIZE in mm 29  HYDROMETER ANALYSIS IS: 2720 (Part 4) – 1985 (Reaffirmed 2006) AIM: To determine the grain size distribution of a given fine grained soil sample by hydrometer analysis. THEORY: Hydrometer analysis is an indirect method of assessing the size of soil particles based on stokes law which relates the velocity with which a spherical particle settles in a still liquid to the diameter of the particle. Hence the size of particle determined in this method is known as equivalent diameter. Hydrometer at any instant measures the relative density of soil suspension. APPARATUS: Hydrometer dispersing cup & stirrer, 1000 cc. jar, balance, dispersing agents, distilled water, thermometer, stop watch etc. CALIBRATION OF HYDROMETER 1. Take about 1000ml of water in one measuring cylinder. Place the cylinder on a table and observe the initial reading. 2. Immerse the hydrometer in the cylinder. Take the reading after the immersion. 3. Determine the volume of the hydrometer ( ) which is equal to the difference between the final and initial readings. Alternatively weigh the hydrometer to the nearest 0.1g. The volume of the hydrometer in ml is approximately equal to its mass in grams. 30 4. Determine the area of cross section (A) of the cylinder. It is equal to the volume indicated between any two graduations divided by the distance between them. The distance is measured with an accurate scale. 5. Measure the distance (H) between the neck and the bottom of the bulb. Record it as the height of the bulb (h). 6. Measure the distance (H) between the neck to each marks on the hydrometer ( ). 7. Determine the effective depth ( ), corresponding to each of the mark ( ) as [Note: the factor should not be considered when the hydrometer is not taken out when taking readings after the start of the sedimentation at ½, 1, 2, and 4 minutes.] 8. Draw a calibration curve between and. Alternatively, prepare a table between and. The curve may be used for finding the effective depth corresponding to reading. 31  CALIBRATION CURVE 20 18 EFFECTIVE DEPTH He 16 14 12 CALIBRATION CURVE 10 8 -5 0 5 10 15 20 25 30 OBSERVED HYDROMETER READING Rh Fig: Hydrometer Calibration Chart PROCEDURE: 1) Take about 50 g of oven dried soil passing through 2 mm sieve. Weight the soil correctly and put it in beaker. 2) Add 100 cc of fresh (2%) solution of dispersing agent (i.e. sodium hexameta phosphate or a mixture of sodium hydroxide and sodium carbonate) into the soil. Add distilled water if necessary and soak the soil for few hours (overnight soaking is desirable for clays). 3) Transfer the soaked soil with water into the dispersion cup (two third full) and stir the mixture for 15 minutes. Put the soil mixture into standard measuring jar and make the total volume of soil suspension 1000 cc by adding distilled water. 4) Calibrate the hydrometer and determine the various hydrometer corrections with the help of tables and charts supplied. (See Appendix). 5) Shake the soil suspension thoroughly without any loss by holding the bottom of the jar with one palm and closing its top with the other and turning it’s upside down. Put the jar back on a level platform. Start the stopwatch. Insert the cleaned hydrometer slowly without allowing any oscillation in the suspension. 6) Take the hydrometer reading R1h (Corresponding to the top of the meniscus) at elapsed time (t) of ½, 1, 2 and 4 minutes. While it floats in the suspension. Enter the observations in the tabular form. 7) Remove the hydrometer from the suspension and place it in a separate jar containing clean water. 8) Repeat steps (5), (6) & (7). Use the average value of readings R 1h obtained from steps (6) & (8) for computation. 32 9) Note the temperature of the soil suspension occasionally throughout the testing period by slowly inserting the thermometer without disturbing the setting of soil particles. 10) Insert the hydrometer in soil suspension just before a reading is desired and remove it (after taking the reading). Hydrometer should not be allowed to touch the side walls of the jar or rest on the settled sediments at the bottom of the jar. 11) Take hydrometer readings at total elapsed time of 8, 15, 30 minutes, 1 hr, 2hr, 4 hr, 8 hr, 12 hrs and 24 hrs. In plastic clay it is desirable to continue the reading until the hydrometer reads 1.000 or 48 hrs of time is elapsed whichever occurs earlier. Or the hydrometer readings may also be taken for elapsed time 1,2,3,4,5,10,15,20,25,30, 45, 60, 90, 120, 240, 720, 1440, 2880 minutes. The recording of observations depends on the type of soil. 12) Compute the equivalent diameter of the soil particle corresponding to any reading of the hydrometer Rh from Stoke’s law as follows : Dmm = √ Where F = f (specific gravity of soil particles and temperature) - Please see table I for this relationship). He = f (Rh) = Rh + Cm from table II 13) Compute the (cumulative) percentage finer (p%) corresponding to R 1h (or Dmm) as follows : p% = ( ) ( ) (Rh + Cm + Ct – Cd – 1.000) x 100 Where G = specific gravity of soil particles V = Volume of soil suspension (generally 1000 cc) Ws = Dry weight of soil used in suspension in g Cm, Ct, Cd = Hydrometer corrections The above formula is valid provided representative test sample with all particle size originally existing in the in-situ soil is used for hydrometer analysis. However generally only the finer fraction passing through either 2.00 mm sieve or 75 micron sieve is used. In which case the actual percentage finer is given by : P=p%x 14) Plot the grain size curve ( p% vs Dmm) incorporating results of the hydrometer analysis. 33 APPENDIX: 1) DETERMINATION OF HYDROMETER CORRECTIONS: During actual use of hydrometer to measure the (relative) density of soil suspension, certain errors creep in. Hence suitable corrections have to be made. The following are the corrections. a. Meniscus correction: (Cm) Normally hydrometer reading flush with the top of the (liquid) suspension level must be read. But generally the suspension adheres to the stem of hydrometer in the form of a meniscus. As the soil suspension is opaque it is not possible to take the hydrometer reading corresponding to the bottom of the meniscus (R 1h)/* is read. As Rh is less than Rh, a negative error results which is compensated by applying the Positive meniscus correction, Cm = R1h – Rh. the value of Cm is determined from R1h and Rh values read from the hydrometer immersed in a transparent liquid (water). b. Temperature correction (Ct): When the temperature of soil suspension is different from the temperature at which hydrometer is calibrated, there will be an error committed in the hydrometer readings. Temperature correction Ct can be determined by reading the hydrometer in liquid (water) at different temperatures. Table-III gives the Ct values for different temperatures. Ct is positive if the observed temperature is more than the temperature at which the hydrometer is calibrated and vice-versa. c. Dispersing agent correction (Cd): 34 Due to the addition of dispersing agent the specific gravity of the suspension increases slightly. Hence a negative correction (Cd) is applied. Its value can be determined by reading hydrometer in plain water and in water with identical amount and type of dispersing agent is used in the soil suspension. d. Displacement (immersion or volume) correction (Ch): Hydrometer measures the specific gravity of the suspension at the centre of gravity of its bulb. In practice the Hydrometer is inserted in the suspension and its readings are noted at different times. As soil particles settle they have the tendency to settle on the neck of the bulb of hydrometer thus affecting its apparent weight. This tendency is not felt at short intervals and hence up to first 4 minutes hydrometer can be allowed to float continuously in the suspension, where after it is removed from suspension immediately after taking a reading and reinserted to enable reading pertaining to a given time. Insertion of hydrometer of volume Vh will raise the liquid surface owing to the displacement of equal volume of liquid. This in turn will affect the calibration He = f (Rh) given in Table-II. For reading beyond 4 minutes, He =He – = He - Ch, Where Aj is the cross sectional area of the jar in which suspension is contained. Table-II also provides the calibration for He = f (Rh) for a standard measuring jar whose internal diameter is 6 cm. INFERENCE: From a discrete analysis of the shape of the grain size distribution curve, the physical and engineering properties can be inferred in a qualitative manner, especially in the case of coarse soils. A well graded curve indicates i) Low void ratio and low porosity. ii) High density. iii) Low permeability and low compressibility and iv) High shear strength. A poorly graded curve has the opposite characteristics. Also from the uniformity co- efficient and effective size, the suitability of a soil in filters etc. can be judged. REPORT OF RESULTS: Draw grain size distribution curve (both sieve & Hydrometer analysis). Find out the percentage of various soil fractions as per I.S: 1498-1970 and co-efficient of uniformity and coefficient of curvature and discuss on the type of soil. 35  Grain size curve of only hydrometer analysis 100 90 80 PERCENTAGE FINER 70 60 50 40 30 20 10 0 0.001 0.010 0.100 1.000 GRAINSIZE in mm Grain size analysis curve of both sieve and hydrometer analysis 100 90 80 PERCENTAGE FINER 70 60 50 40 30 20 10 0 0.001 0.010 0.100 1.000 10.000 GRAINSIZE in mm 36  TABLE – I VALUES OF F FOR USE IN FOR USE IN FORMULA FOR COMPUTING DIAMETER OF PARTICLE (Dmm) IN HYDROMETER ANALYSIS Temp. Specific Gravity in OC 2.50 2.55 2.60 2.65 2.70 2.75 2.80 15 0.01528 0.01503 0.01479 0.01458 0.01435 0.01414 0.01395 16 0.01508 0.01483 0.01460 0.01438 0.01417 0.01396 0.01377 17 0.01490 0.01465 0.01442 0.01420 0.01399 0.01379 0.01360 18 0.01470 0.01446 0.01406 0.01402 0.01381 0.01361 0.01342 19 0.01452 0.01428 0.01389 0.01384 0.01364 0.01344 0.01325 20 0.01434 0.01411 0.01372 0.01367 0.01347 0.01328 0.01309 21 0.01417 0.01393 0.01355 0.01351 0.01331 0.01311 0.01294 22 0.01400 0.01377 0.01339 0.01335 0.01315 0.01296 0.01278 23 0.01383 0.01360 0.01323 0.01318 0.01299 0.01280 0.01262 24 0.01367 0.01344 0.01308 0.01305 0.01284 0.01265 0.01248 25 0.01351 0.01329 0.01293 0.01288 0.01269 0.01251 0.01233 26 0.01335 0.01313 0.01279 0.01273 0.01254 0.01236 0.01219 27 0.01321 0.01299 0.01264 0.01244 0.01241 0.01224 0.01191 28 0.01305 0.01284 0.01250 0.01231 0.01226 0.01069 0.01178 29 0.01291 0.01270 0.01236 0.01217 0.01213 0.01208 0.01165 30 0.01277 0.01256 0.01224 0.01205 0.01199 0.01195 0.01154 31 0.01264 0.01243 0.01211 0.01193 0.01187 0.01182 0.01142 32 0.01251 0.01230 0.01195 0.01180 0.01175 0.01170 0.01130 33 0.01238 0.01218 0.01186 0.01168 0.01163 0.01158 0.01118 34 0.01225 0.01205 0.01174 0.01156 0.01151 0.01146 0.01107 35 0.01212 0.01191 0.01161 0.01144 0.01139 0.01134 0.01095 36 0.01199 0.01180 0.01150 0.01139 0.01127 0.01120 0.01084 37 0.01188 0.01169 0.01139 0.01122 0.01116 0.01110 0.01064 38 0.01176 0.01157 0.01128 0.01110 0.01105 0.01100 0.01064 37 39 0.01165 0.01146 0.01118 0.01101 0.01094 0.01089 0.01055 40 0.01155 0.01136 0.01108 0.01092 0.01084 0.01079 0.01045 TABLE – II CALIBRATION OF HYDROMETER Relationship between Zr and Rh values for Hydrometer analysis. Reading of the Zr value without volume Zrc =Zr + Ch for use Hydrometer correction Ch for use up beyond 4 minutes RH = R’H + CN to 4 minutes 1 2 3 0.995 21.655 20.500 0.996 21.355 20.200 0.997 21.055 19.900 0.998 20.755 19.600 0.999 20.455 19.300 1.000 20.155 19.000 1.001 19.855 18.700 1.002 19.555 18.400 1.003 19.255 18.100 1.004 18.955 17.800 1.005 18.655 17.500 1.006 18.355 17.200 1.007 18.055 16.900 1.008 17.755 16.600 1.009 17.455 16.300 1.010 17.155 16.000 1.011 16.855 15.700 1.012 16.555 15.400 1.013 16.255 15.100 1.014 15.955 14.800 1.015 15.655 14.500 1.016 15.355 14.200 1.017 15.055 13.900 1.018 14.755 13.600 1.019 14.455 13.300 1.020 14.155 13.000 1.021 13.855 12.700 1.022 13.555 12.400 1.023 13.255 12.100 1.024 12.955 11.800 38  1.025 12.655 11.500 1.026 12.355 11.200 1.027 12.055 10.900 1.028 11.755 10.600 1.029 11.455 10.300 1.030 11.155 10.000 HYDROMETER ANALYSIS RECORDING OF OBSERVATION Soil Type: Hydrometer (Type): Specific gravity (Gs): Volume of the suspension (Vcc): Weight of the dry soil (Ws g) : Gradation of soil used: Date Time Elapsed time t (min) 0.5 1 2 4 5 8 10 15 20 30 45 60 90 120 240 480 1440 39  TABLE – III TEMPERATURE CORRECTION (Ct) FOR HYDROMETER ANALYSIS Temperature in OC Temperature Correction (Ct) 20.0 0.00000 20.5 0.00009 21.0 0.00017 21.5 0.00027 22.0 0.00037 22.5 0.00049 23.0 0.00058 23.5 0.00068 24.0 0.00081 24.5 0.00091 25.0 0.00102 25.5 0.00116 26.0 0.00127 26.5 0.00139 27.0 0.00150 27.5 0.00163 28.0 0.00178 28.5 0.00191 29.0 0.00206 29.5 0.00219 30.0 0.00232 30.5 0.00247 31.0 0.00262 31.5 0.00278 32.0 0.00291 32.5 0.00320 33.0 0.00350 33.5 0.00380 34.0 0.00400 34.5 0.00420 35.5 0.00440 36.0 0.00470 40  CALIFORNIA BEARING RATIO CBR TEST IS: 2720(Part 16)-1973 (Reaffirmed 2002) OBJECTIVE Determination of CBR of soil either in undisturbed or Remoulded condition EQUIPMENTS / APPARATUS  Load Frame / Compression machine  Proving ring, Dial gauge, Timer  Sampling tube  Split mould  Vernier caliper, Balance PREPARATION OF SAMPLE The test may be performed (a) On undisturbed soil specimen (b) On remoulded soil specimen (a) On undisturbed specimen Undisturbed specimen is obtained by fitting to the mould, the steel cutting edge of 150 mm internal diameter and pushing the mould as gently as possible into the ground. When the mould is sufficiently full of soil, it shall be removed by under digging. The top and bottom surfaces are then trimmed flat so as to give the required length of specimen. (b) remouldedSpecimens The dry density for remoulding should be either the field density or if the subgrade is to be compacted, at the maximum dry density value obtained from the Proctor Compaction / light compaction test. If it is proposed to carry out the CBR test on an unsoaked specimen, the moisture content for remoulding should be the same as the equilibrium moisture content which the soil is likely to reach subsequent to the construction of the road. If it is proposed to carry out the CBR test on a soaked specimen, the moisture content for remoulding should be at the optimum and soaked under water for 96 hours. Soil Sample – The material used in the remoulded specimen should all pass through a 19 mm IS sieve. Allowance for larger material may be made by replacing it by an equal amount of material which passes a 19 mm sieve but is retained on a 4.75 mm IS sieve. This procedure is not satisfactory if the size of the soil particles is predominantly greater than 19 mm. The specimen may be compacted statically or dynamically. 41 I. Compaction by Static Method The mass of the wet soil at the required moisture content to give the desired density when occupying the standard specimen volume in the mould is calculated. A batch of soil is thoroughly mixed with water to give the required water content. The correct mass of the moist soil is placed in the mould and compaction obtained by pressing in displacer disc, a filter paper being placed between the disc & soil. II. Compaction by Dynamic Method For dynamic compaction, a representative sample of soil weighing approximately 4.5 kg or more for fine grained soils and 5.5 kg or more for granular soil shall be taken and mixed thoroughly with water. If the soil is to be compacted to the maximum dry density at the optimum water content determined in accordance with light compaction or heavy compaction, the exact mass of soil required is to be taken and the necessary quantity of water added so that the water content of soil sample is equal to the determined optimum water content. The mould with extension collar attached is clamped to the base plate. The spacer disc is inserted over the base plate and a disc of coarse filter paper placed on the top of the spacer disc. The soil water mixture is compacted into the mould in accordance with the methods specified in light compaction test or heavy compaction test. For OMC & MDD of light compaction test apply 56 blows in 3 layers-2.6 kg hammer. For OMC & MDD of heavy compaction test apply 56 blows in 5 layers- 4.89 kg hammer. PROCEDURE 1. The mould containing the specimen with the base plate in position but the top face exposed is placed on the lower plate of the testing machine. 2. Surcharge weights, sufficient to produce an intensity of loading equal to the weight of the base material and pavement is placed on the specimen. 3. To prevent upheaval of soil into the hole of the surcharge weights, 2.5 kg annular weight is placed on the soil surface prior to seating the penetration plunger after which the remainder of the surcharge weight is placed. 4. The plunger is to be seated under a load of 4 kg so that full contact is established between the surface of the specimen and the plunger. 5. The stress and strain gauges are then set to zero. Load is applied to the penetration plunger so that the penetration is approximately 1.25 mm per minute. 6. Readings of the load are taken at penetrations of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 4.0, 5.0, 7.5, 10.0 and 12.5 mm. 7. The plunger is then raised and the mould detached from the loading equipment. CALCULATION: Load-Penetration curve: The load penetration curve is plotted taking penetration value on x-axis and Load values on Y-axis. Corresponding to the penetration value at which the CBR is desired, corrected load value is taken from the load-penetration curve and the CBR calculated as follows 42 California bearing ratio = (PT/PS)x100 Where PT = Corrected unit (or total) test load corresponding to the chosen penetration curve, and PS = Unit(or total) standard load for the same depth of penetration as for PStaken from standard code. CBR: STANDARD LOAD Penetration Depth (mm) Unit Standard Load (kg/cm2) Total Standard Load (kg) 2.5 70 1370 5 105 2055 7.5 134 2630 10 162 3180 12.5 183 3600 TABULATION: Corrected Proving Test Test Standard CBR 120 Penetration Ring Load Load Load Value Reading mm (div) kg (kg) (kg) (%) 100 0.00 0 0 0.50 8 16 80 LOAD IN kg 1.00 14 28 1.50 20 40 60 2.00 25 50 2.50 30 60 60.00 1370 4.38 40 3.00 33 66 3.50 35 70 20 4.00 37 74 4.50 39 78 0 5.00 40 80 80.00 2055 3.89 0 2.5 5 7.5 10 12.5 7.50 46 92 PENETRATION IN mm 10.00 50 100 12.50 53 106 REPORT The CBR values are usually calculated for penetration of 2.5 mm and 5 mm. Generally, the CBR value at 2.5 mm penetration will be greater than that at 5 mm penetration. If the CBR value corresponding to a penetration of 5 mm exceeds that for 2.5 mm, the test shall be repeated. If identical results follow, the bearing ratio corresponding to 5 mm penetration shall be taken for design. The CBR value is reported correct to the first decimal place. 43  NORTH DAKOTA CONE TEST IS: 2720 (Part-32)-1970 AIM-To determine the cone bearing value of given soils. SCPOE AND LIMITATION-test may be made on subgrade either in its natural state or sample prepared by compaction or stabilization. This test may be conducted at site or on soil compacted in a C.B. R mould. This test gives good results only on fine grained cohesive soils. A little piece of stone may give rise to erratic result. Many tests have to be carried out to find the average value. DESCRIPTION OF APPARATUS: It consist of a shaft with a sharp cone attached. It is supported by a frame which facilitates the vertical free movement. Frame rests uniformly on a leveled surface. A rod graduated in 1/20th of an inch moves through the frame along with the shaft. The weights are increased on the plate fixed to the shaft. PROCEDURE 1. Place the compacted soil in the C.B.R mould under the cone of cone penetrometer , just touching the top of compacted soil. 2. Note down the reading on the graduated scale. 3. Allow the cone to penetrate the soil mass by unlocking the shaft screw and note the penetration after one minute. 4. Find the difference of final and intial reading,which gives the amount of penetration. 5. Increase the load to 10 kg and note down the penetration. 6. Find out the penetration corresponding to 15, 20, 25, 30, 35, 40 kg, loads after one minute each as before. TABULATION: Bearing area= π(Corrected penetration x tan ½ cone angle)2 Load(kg) Penetration Corrected Bearing value = reading penetration Load / Bearing area 5 (Self wt) 10 15 20 25 30 35 40 CALCULATION Correction ‘c’ to be applied to all penetration readings is given by, C=P40 – 2P10 P40 – penetration at 40 kg load and P10 – penetration at 10 kg load The semi vertical angle of cone is 15o30’ from which the reading and area of cross section at surface level of the cone can be calculated. Graph: plot the graph between corrected penetration versus bearing value. 44  DIRECT SHEAR TEST IS: 2720 (Part 13) – 1986 (Reaffirmed 2002) AIM: To determine the shear parameters of a given soil sample (undisturbed/remoulded) using a direct shear test apparatus. THEORY: The shear strength of a soil is given by Mohr-Coulomb expression. S = C+ σ tan Φ Where, S – Shear strength, kg/cm2 σ -Normal stress on failure plane, kg/cm2 C-Unit Cohesion, kg/cm2 Φ-Angle of internal friction (degree) In a strength test of soil, there are two basic stages. First a normal load is applied to the specimen (consolidation stage) and then failure is induced by applying a shear stress (shearing stage). If no water is allowed to escape from or enter into specimen either during consolidation or during shearing then it is called undrained test or unconsolidated undrained test (quick test). If the specimen is allowed to consolidate under the normal load, but no drainage of water is allowed during shear, it is consolidated undrained or (consolidated quick) test. If the specimen is consolidated under the normal load & sheared under fully drained conditions, it is called (consolidated drained or slow) test. APPARATUS: Shear box with its accessories, loading frame, proving ring, dial gauges. Sample trimmer, balance, weights, spatula, vernier porous stone, grid plate, blotting paper etc. 45 PREPARATION OF SAMPLE: a) REMOULDED SPECIMEN: i) Cohesive soils may be compacted to the required density and moisture content, the sample extracted and then trimmed to the required size. Alternatively the soil may be compacted to the required density and moisture content directly into the shear box after fixing the two halves of the shear box together by means of the fixing screws. ii) Non-cohesive soils may be tamped in the shear box itself with the base plate and grid plate or porous stone as required in place at the bottom of the box. b) UNDISTURBED SPECIMEN: Specimens of required size shall be trimmed from undisturbed samples. PROCEDURE:- a) UNDRAINED TEST: 1. Prepare the soil sample as described above. The soil should not contain particles more than 4.75mm. size. 2. Note that the grooves of both top and bottom grid plates should be at right angles to the direction of shear. Place the loading pad on the top of the grid plate. 46  3. Transfer the box into the water jacket placed (on-rollers) on the platform of the apparatus provided with an adjustable loading frame. See that the shear box is in its centre. 4. Determine the leverage ratio and apply the desired normal load intensity in the range of 0.5 to 2 kg/cm2 through the loading frame. Adjust the proving ring so that its attached spindle touches the water jacket auto surface. Remove the locking screws. 5. Attach a dial gauge to the fitting fixed to the vertical end plate. This gauge measures the shear (horizontal) displacement. 6. Induce shear displacement at a rate of about 1% strain per minute 0.6mm/ minute. 7. Take the readings of proving ring dial gauge at every 0.6mm of shear displacement till failure of till a displacement of 12mm (20% strain) which occurs earlier. 8. Repeat the test on at least two more (total 3 samples) identical specimens under increased normal loads. May be 0.5, 1, 1.5 kg/cm2. b) CONSOLIDATED UNDRAINED TEST: Procedure is similar to that in undrained test, except that instead of solid grid plates use perforated grid plates at top and bottom of the specimen conduct the shear test only after complete consolidation has occurred under the applied normal stress. The rate of strain may be kept as above. c) CONSOLIDATED DRAINED TEST: Procedure is similar to that in consolidated undrained test except that the shearing is done at a slow rate so that complete drainage can occur, during the shear stage. For sandy soils a rate of strain of 0.2mm/minute may be suitable. For clayey soils a rate of strain of 0.01mm/minute or slower may be used. CALCULATION: Calculate the corrected cross sectional area Ac(kg/cm2) from the following equation. Ac= A0 * [1-(Δ/B)] Where, A-Initial cross-sectional area of the specimen, cm2 Δ - Displacement (cm) B-Initial length of specimen 47 Find out the shear load corresponding the proving ring reading. Find out the shear stresses at a given shear strain by dividing the shear load by correct area of specimen. GRAPHS: i) Plot the shear strain versus shear stress curves to obtain the maximum shear stress.Determine the failure strain. ii) Plot failure (or maximum) shear stress versus normal stress to obtain the shear parameters c and ɸ. GENERAL REMARKS 1. In the shear box test, the specimen is not failing along its weakest plane but along a predetermined or induced failure plane i.e. horizontal plane separating the two halves of the shear box. This is the main draw back of this test. Moreover, during loading, the state of stress cannot be evaluated. It can be evaluated only at failure condition i.e Mohr’s circle can be drawn at the failure condition only. Also failure is progressive. 2. Direct shear test is simple and faster to operate. As thinner specimens are used in shear box, they facilitate drainage of pore water from a saturated sample in less time. This test is also useful to study friction between two materials - one material in lower half of box and another material in the upper half of box. 3. The angle of shearing resistance of sands depends on state of compaction, coarseness of grains, particle shape and roughness of grain surface and grading. It varies between 28o (uniformly graded sands with round grains in very loose state) to 46o(well graded sand with angular grains in dense state). 4. The volume change in sandy soil is a complex phenomenon depending on gradation, particle shape, state and type of packing, orientation of principal planes, principal stress ratio, stress history, magnitude of minor principal stress, type of apparatus, test procedure, method of preparing specimen etc. In general loose sands expand and dense sands contract in volume on shearing. There is a void ratio at which either expansion contraction in volume takes place. This void ratio is called critical void ratio. Expansion or contraction can be inferred from the movement of vertical dial gauge during shearing. 48  5. The friction between sand particle is due to sliding and rolling friction and interlocking action. The ultimate values of shear parameter for both loose sand and dense sand approximately attain the same value so, if angle of friction value is calculated at ultimate stage, slight disturbance in density during sampling and preparation of test specimens will not have much effect. TABULATION- DIRECT SHEAR TEST: Soil type: Initial dimensions of the specimen: Initial weight of specimen: Bulk density of specimen: Moisture content of specimen: Tested by: Proving ring no: Proving ring constant: Lever arm factor: Specimen No. 1 2 3 1.Horizontal displacement (cm) 2.corrected area, cm2 3.proving ring reading 4.Shear load (Kg) 5.Shear stress, kg/cm2 NORMAL SHEAR STRESS STRESS (kg/cm2) Proving Ring Reading Proving Shear Force (kg) Shear Stress (Division) Ring (kg/cm2) Constant 0.5 78 0.400 31.200 0.9 1 110 0.400 44.000 1.2 1.5 145 0.400 58.000 1.6 49  SHEAR PARAMETERS c = 0.5 kg/cm2, Φ = 36.30 2.00 SHEAR STRESS ( kg/cm2) 1.50 1.00 0.50 0.00 0 0.5 1 1.5 2 NORMAL STRESS (kg/cm2) REPORT OF RESULT: The unconsolidated undrained/consolidated undrained/ consolidated drained shear parameter of the given soil sample with dry density of ___________ and moisture content of___________ , in direct shear test was found to be c= ______________ kg/cm2 and ɸ=________ degrees. 50  SOIL pH IS: 2720 (Part 26) – 1987 (Reaffirmed 2002) pH is a measure of the level of acidity or alkalinity in the soil. The pH scale ranges from 0 to 14 and reflects the hydrogen ion concentration in the soil. A pH value of 7.0 is neutral. Values below 7.0 are acidic; those above 7.0 are alkaline or basic. Soil pH has an impact on the availability of most nutrients. Elements such as nitrogen, calcium and molybdenum are less available at pH levels below 6.0. The availability of other nutrients, such as manganese, zinc, phosphorus and potassium decreases at pH levels greater than 7.0. Vegetables grown on mineral soils have a target pH of 6.1 to 6.5. On muck soils the target pH is 5.1 to 5.5. pH also affects the activity of soil micro-organisms. These organisms build soil structure, cycle organic matter or fix nitrogen in legume nodules. pH = - log10 (H+) = log10 1/H+ wherein H+ is the hydrogen ion-concentration in moles/litre. In pure water, at 25oC, H+ = 1.00 x 10-7 and thus pH = 7.00. This value corresponds to exact neutrality. Definition: The pH value of solution is the negative logarithm of Hydrogen Ion activity. Electrometric method Instrument: A glass electrode, pH meter with calomel reference electrode. Procedure: Standard Buffer Solution-These may be of pH 4.0 and in other ranges of expected soil pH values. In case of buffer tablets (available commercially), a single piece is to be dissolved in double distilled water and made up to 100ml. A 0.05 m solution of Potassium Hydrogen pthalet gives pH 4.0 & can also be used. It is necessary to prepare fresh solutions after a few days as the buffers do not keep for long. 30gm of soil is taken in 100ml beaker to which 75ml of distilled water are added. The suspension is steered at regular intervals for 30 minutes. Then pH is recorded. The suspension must be steered well just before the electrodes are immersed. pH meter is calibrated with 2 buffers , one in the acidic side and the other alkaline or neutral range. The glass & calomel electrodes are inserted in suspension and pH measurement is made. 51 52  PERMEABILITY OF SOIL CONSTANT HEAD METHOD IS: 2720 (Part 17) – 1986 (Reaffirmed 2002) AIM: To determine the coefficient of permeability (k) of a remoulded coarse grained soil sample with a constant head permeameter. THEORY: The coefficient of permeability (k) of a soil is defined as the rate of discharge of water through a unit cross sectional area of a soil under unit hydraulic gradient for a laminar flow condition. This can be determined in the laboratory by constant head permeability test for coarse grained soil with k value greater than 10-3cm/sec. APPARATUS: 1. Permeameter mould with collar 2. Tot cap with water inlet nozzle, air release valve 3. Perforated top and bottom plates 4. Constant head tank 5. Tamping rod 6. Stop watch, scale, measuring cylinder, spanner, grease, thermometer, etc. 53 PROCEDURE: 1. Remove the oversize particles by sieving the soil specimen through IS 20mm sieve and determine its %. 2. Note the dimensions of the permeameter and calculate its volume (1000 cm3 for a standard instrument). 3. For testing remoulded soil sample, first calculate the amount of dry soil and water required to achieve a particular density and moisture content. 4. Mark the height of mould into three equal parts and also divide the soil into three equal parts. 5. Compact the soil into the mould in layers after fixing the mould to its base plate containing porous stone and placing the collar on top. 6. Put the porous stone on the top of the soil and fix the top plate which is provided with an inlet valve and air cock. Secure both the base plate and the top plate to mould with suitable clamps and rubber gasket to make the entire assembly water tight. 7. Place the assembly in a shallow metal tray with an out-let.Fill the tray with water submerge the base plate completely. All the heads of water must be measured with respect to the tail water level corresponding to the centre of the out-let pipe or crest of the outlet in tray. 8. Attach the constant head water tank with the sliding bracket to a vertical stand. This tank has three opening connect one of them to water supply source, the second to the overflow tube and the third to the inlet valve provided on the cap of the permeameter. Remove all the air bubbles with the help of the air cock, provided on the top plate. Allow the soil sample to saturate. Check this by obtaining constant values of discharge collected over a given time under a given head. 9. When steady flow is attained, collect sufficient quantity of water (about 250cc) and note the time interval. Take three observations. 10. Note the total head loss and the length of specimen and note the temperature of water. 11. Repeat the test for three different hydraulic heads. TABULATION (CONSTANT HEAD PERMEABILITY TEST): Dia of mould = Area of mould ( A ) = Length of mould ( L)= Volume of mould (V ) = 1000 cm3 (For a standard mould) Temperature of water ( T ) = 54 Specific gravity of soil (GS ) = Void ratio (e ) = Dry density = Sl. No. Head (h)cm Quantity of Time (T)sec Permeability Remarks water (Q)cc cm/sec 1 2 3 4 5 6 CALCULATION: The permeability at the test temperature can be found at by the following formula QL KT = ----------- Ath Where :- KT : Coefficient of permeability at temperature T Q : Quantity of water discharge L : Length of soil specimen A : Cross sectional area of specimen t : Total time of discharge (minutes) h : Head loss The temperature correction shall be applied by the following formula: GT K27 = KT --------- G27 Where :- K27 : Coefficient of permeability at 270c KT : Coefficient of permeability at test temperature GT : Viscosity of water at T0c G27 : Viscosity of water at 270c REPORT OF RESULTS: The reports of permeability test shall include the following information: (a) Grain size analysis, maximum particle size, and percentage of any over size material not used, (b) Dry unit weight, void ratio, (c) Average value of permeability obtained in cm/sec. 55  PERMEABILITY OF SOIL VARIBALE HEAD METHOD IS: 2720(PART 17)-1986 (Reaffirmed 2002) AIM: To determine the coefficient of permeability of the given fine grained (remoulded/undisturbed) soil sample using variable head permeameter. THEORY: The coefficient of permeability (k) of a soil is defined as the rate of discharge of water through a unit cross sectional area of the soil under unit hydraulic gradient under laminar flow condition. This can be determined in the laboratory by variable head permeability test for fine grained soils with k less than 10-3cm/sec. APPARATUS: 1. Permeameter mould with collar. 2. Top cap with water inlet nozzle, air release valve. 3. Perforated base plate & filter paper. 5. Falling head stand pipe. 6. Stop watch, scale, measuring cylinder, spanner, grease thermometer etc. 56 PROCEDURE: 1. Remove the oversize particles by sieving the soil specimen through IS 20mm. sieve & determine its percentage. 2. Note the dimensions of permeameter mould and calculate its volume. 3. For testing an undisturbed soil sample, obtain the sample into mould. Trim the soil sample if necessary and weigh the mould with soil sample, knowing the weight of empty mould, find the weight of undisturbed sample. Determine the natural water content of sample from soil trimmings. 4. For testing the remoulded sample, first calculate the weight of dry soil and amount of water required to bring the compacted soil in mould to M.D.D. and O.M.C as found out by standard proctor test. 5. Mix the soil with water & keep for some to allow through mixing of water and maturation of soil and divide the soil into three equal parts. 6. Compact the soil into mould in three equal layers, after fixing the mould to its base plate. Put a filter paper on top & bottom of soil. 7. Attach the top cap with sand pipe and scale to the mould and lighten the bolts to make the assembly water tight. 8. Place the assembly in a shallow metal tray with an outlet. Fill the tray with water to submerge the base plate completely. 9. Pour water into the stand pipe and allow it to run through the sample. Operate the air cock to remove any air present. Check the saturation of soil by noting the same full of head of water from the same initial head for equal time intervals. 10. Determine the cross sectional area of stand pipe by pouring known volume of water (5 cc) measured by means of a pipette into the stand pipe. The cross sectional area of stand pipe a= volume of water poured into the stand pipe/water level rise in stand pipe. 11. Open the inlet valve and allow the water to flow through the soil sample. Note the initial height(h1) of the water level in the stand pipe and at the same time start a stop watch. 12. Allow sufficient time so that water level falls by about 30 to 50 cm in the stand pipe. Stop the watch and note the height (h2) of the water level in the stand pipe at that instant. 13. Fill the stand pipe again with water and repeat the same