EXPERIMENT 1 SIEVE AND HYDROMETER ANALYSIS (GRAIN SIZE ANALYSIS) (PREPARED BY : AHMAD FAIZAL MANSOR)

Transcription

1 EXPERIMENT 1 SIEVE AND HYDROMETER ANALYSIS (GRAIN SIZE ANALYSIS) (PREPARED BY : AHMAD FAIZAL MANSOR) 1.0 OBJECTIVE This test is performed to determine the percentage of different grain sizes contained within a soil. 2.0 INTRODUCTION Grain size analysis is a process in which the proportion of material of each grain size present in a given soil (grain size distribution) is determined. The grain size distribution of coarse-grained soils is determined directly by sieve analysis, while that of fine-grained soils is determined indirectly by hydrometer analysis. The grain size distribution of mixed soils is determined by combined sieve and hydrometer analyses. The grain size analysis is presented as a semi log plot of percent finer versus particle size, called a grain size distribution curve. A semi log plot is used for the particle sizes to give both small and large diameters as nearly equal weight as possible. Percent finer is always plotted as the ordinate using an arithmetic scale. From the grain size distribution curve, grain sizes such as D10, D30 and D60 can be obtained. The D refers to the size, or apparent diameter, of the soil particles and the subscript (10, 30, 60) denotes the percent that is smaller. For example, D10 = 0.16 mm means that 10 percent of the sample grains are smaller than 0.16 mm. The D10 size is also called the effective size of the soil. An indication of the spread (or range) of particle sizes is given by the coefficient of uniformity (C u ), which is defined as C u = D60 D10 1

2 The coefficient of curvature (C c ) is a measure of the shape of the curve between the D60 and D10 grain sizes, and is defined as C c = (D30) 2 D60 * D Sieve Analysis A sieve analysis consists of passing a sample through a set of sieves and weighing the amount of material retained on each sieve. Sieves are constructed of wire screens with square openings of standard sizes. The sieve analysis is performed on material retained on an U. S. Standard No. 200 sieve. Table A gives a list of the U. S. Standard sieve numbers with their corresponding size of openings. Table A: U. S. Sieve Numbers and Associated Opening Sizes Sieve No. Opening Size (mm) Sieve No. Opening Size (mm)

3 2.2 Hydrometer Analysis A hydrometer is an instrument used to measure the specific gravity (or relative density) of liquids; that is, the ratio of the density of the liquid to the density of water. A hydrometer is usually made of glass and consists of a cylindrical stem and a bulb weighted with mercury or lead shot to make it float upright. The liquid to be tested is poured into a tall jar, and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer is noted. Hydrometers usually contain a paper scale inside the stem, so that the specific gravity can be read directly Cylindrical stem Bulb (weighted with mercury/lead shot) A hydrometer analysis is the process by which fine-grained soils, silts and clays, are graded. Hydrometer analysis is performed if the grain sizes are too small for sieve analysis. The basis for this test is Stoke's Law for falling spheres in a viscous fluid in which the terminal velocity of fall depends on the grain diameter and the densities of the grain in suspension and of the fluid. The grain diameter thus can be calculated from a knowledge of the distance and time of fall. 3

4 The operation of the hydrometer is based on the Archimedes principle that a solid suspended in a liquid will be buoyed up by a force equal to the weight of the liquid displaced. Thus, the lower the density of the substance, the further the hydrometer will sink. The relative density of a liquid can be measured using a hydrometer. This consists of a bulb attached to a stalk of constant cross-sectional area, as shown in the diagram to the right. First the hydrometer is floated in the reference liquid (lighter colored), and the displacement (the level of the liquid on the stalk) is marked. The reference could be any liquid, but in practice it is usually water. The hydrometer is then floated in a liquid of unknown density (darker colored). The change in displacement, Δx, is noted. In the example depicted, the hydrometer has dropped slightly in the darker colored liquid; hence its density is lower than that of the reference liquid. It is, of course, necessary that the hydrometer floats in both liquids. The application of simple physical principles allows the relative density of the unknown liquid to be calculated from the change in displacement. (In practice the stalk of the hydrometer is pre-marked with graduations to facilitate this measurement.) By running the hydrometer analysis test in conjunction with the sieve analysis test, the grain-size distribution curve can be plotted and the soil can be classified. After classifying a soil according to the Unified or the AASHTO classification system, the soil can be used for engineering purposes. 4

5 3.0 TEST EQUIPMENTS a) Balance b) Set of sieves c) Cleaning brush d) Sieve shaker e) Mixer (blender) f) 152H Hydrometer g) Sedimentation cylinder h) Control cylinder i) Thermometer j) Beaker k) Timing device 5

6 4.0 PROCEDURES 4.1 Sieve Analysis 1. Write down the weight of each sieve as well as the bottom pan to be used in the analysis. 2. Record the weight of the given dry soil sample (initially oven-dry sample of soil). 3. Make sure that all the sieves are clean, and assemble them in the ascending order of sieve numbers (#4 sieve at top and #200 sieve at bottom). Place the pan below #200 sieve. Carefully pour the soil sample into the top sieve and place the cap over it. 4. Place the sieve stack in the mechanical shaker and shake for 10 minutes. 5. Remove the stack from the shaker and carefully weigh and record the weight of each sieve with its retained soil. In addition, remember to weigh and record the weight of the bottom pan with its retained fine soil. 4.2 Hydrometer Analysis 1. Take the fine soil from the bottom pan of the sieve set, place it into a beaker, and add 125 ml of the dispersing agent (sodium hexametaphosphate (40 g/l)) solution. Stir the mixture until the soil is thoroughly wet. Let the soil soak for at least ten minutes. 2. While the soil is soaking, add 125mL of dispersing agent into the control cylinder and fill it with distilled water to the mark. Take the reading at the top of the meniscus formed by the hydrometer stem and the control solution. A reading less than zero is recorded as a negative (-) correction and a reading between zero and sixty is recorded as a positive (+) correction. This reading is called the zero correction. The meniscus correction is the difference between the top of the meniscus and the level of the solution in the control jar (Usually about +1). Shake the control cylinder in such a way that the contents are mixed thoroughly. Insert the hydrometer and thermometer into the control cylinder and note the zero correction and temperature respectively. 6

7 3. Transfer the soil slurry into a mixer by adding more distilled water, if necessary, until mixing cup is at least half full. Then mix the solution for a period of two minutes. 4. Immediately transfer the soil slurry into the empty sedimentation cylinder. Add distilled water up to the mark. 5. Cover the open end of the cylinder with a stopper and secure it with the palm of your hand. Then turn the cylinder upside down and back upright for a period of one minute. (The cylinder should be inverted approximately 30 times during the minute.) 6. Set the cylinder down and record the time. Remove the stopper from the cylinder. After an elapsed time of one minute and forty seconds, very slowly and carefully insert the hydrometer for the first reading. (Note: It should take about ten seconds to insert or remove the hydrometer to minimize any disturbance, and the release of the hydrometer should be made as close to the reading depth as possible to avoid excessive bobbing). 7. The reading is taken by observing the top of the meniscus formed by the suspension and the hydrometer stem. The hydrometer is removed slowly and placed back into the control cylinder. Very gently spin it in control cylinder to remove any particles that may have adhered. 8. Take hydrometer readings after elapsed time of 2 and 5, 8, 15, 30,60 minutes and 24 hours. 7

8 5.0 RESULTS 5.1 Sieve Analysis: 1. Obtain the mass of soil retained on each sieve by subtracting the weight of the empty sieve from the mass of the sieve + retained soil, and record this mass as the weight retained on the data sheet. The sum of these retained masses should be approximately equals the initial mass of the soil sample. A loss of more than two percent is unsatisfactory. 2. Calculate the percent retained on each sieve by dividing the weight retained on each sieve by the original sample mass. 3. Calculate the percent passing (or percent finer) by starting with 100 percent and subtracting the percent retained on each sieve as a cumulative procedure. 4. Make a semi logarithmic plot of grain size vs. percent finer. 5. Compute Cc and Cu for the soil. 5.2 Hydrometer Analysis: 1. Apply meniscus correction to the actual hydrometer reading. 2. From Table 1, obtain the effective hydrometer depth L in cm (for meniscus corrected reading). 3. For known G s of the soil (if not known, assume 2.65 for this lab purpose), obtain the value of K from Table Calculate the equivalent particle diameter by using the following formula: Where t is in minutes, and D is given in mm. 5. Determine the temperature correction C T from Table Determine correction factor a from Table 4 using G s. 8

9 7. Calculate corrected hydrometer reading as follows: R c = R ACTUAL - zero correction + C T 8. Calculate percent finer as follows: Where W S is the weight of the soil sample in grams. 9. Adjusted percent fines as follows: F 200 = % finer of #200 sieve as a percent 10. Plot the grain size curve D versus the adjusted percent finer on the semi logarithmic sheet. 9

10 Table 1. Values of Effective Depth Based on Hydrometer and Sedimentation Cylinder of Specific Sizes 10

11 Table 2. Values of k for Use in Equation for Computing Diameter of Particle in Hydrometer Analysis Table 3. Temperature Correction Factors C T Table 4. Correction Factors a for Unit Weights of Solids Sample Results Template/Data sheet 11

12 Sieve Analysis Date Tested : Tested by : Project Name : Sample Number : Visual Classification of Soil : Weight of Container : gm Weight container + Dry Soil : gm Weight of Dry Sample : gm Sieve Number Diameter (mm) Mass of Empty Sieve (g) Mass of Sieve + Soil Retained (g) Soil Retained (g) Pan --- Total Weight= *Percent passing = 100 cumulative percent retained Percent Retained Percent Passing From Grain Size Distribution Curve: % Gravel = D 10 = mm %Sand = D 30 = mm % Fines = D 60 = mm C u = C c = 12

13 Hydrometer Analysis Test Date : Tested By : Hydrometer Number (if known) : Specific Gravity of Solids : Dispersing Agent : Weight of Soil Sample : gm Zero Correction : Meniscus Correction : Date Tim e Elapse d Time (min) Tem p. ( 0 C) Actual Hydro. Rdg. R a Hydro. Corr. For Meniscus L from Table 1 K from Table 2 D mm C T from Tabl e 3 a from Table 4 Corr. Hydr o. Rdg. R c % Fine r P % Adjuste d Finer P A 11

14 Semi logarithmic Sheet Note: You can plot your data on this graph or generate similar graph using any graphics program (e.g. Excel) 6.0 DISCUSSIONS (Include a discussion on the result noting trends in measured data, and comparing measurements with theoretical predictions when possible. Include the physical interpretation of the result, the reasons on deviations of your findings from expected results, your recommendations on further experimentation for verifying your results, and your findings.) 7.0 CONCLUSION (Base on data and discussion, make your overall conclusion) 12

15 8.0 QUESTIONS 1. What were the possible sources of error in this lab experiment? 2. What could be done to reduce the error? 3. Is it possible to carry out a sieve analysis on a sample of silt? Why? 4. State the limitation(s) of Sieve Analysis. 5. What do you personally understand about the grain size analysis, and what are the benefits/outcomes acquired by executing this test in real engineering application? 6. How grain size distribution affects permeability? 13

16 EXPERIMENT 2 DETERMINATION OF LIQUID LIMIT AND PLASTIC LIMIT OF SOIL (PREPARED BY : LIYANA AHMAD SOFRI) OBJECTIVES To determine the liquid limit and plastic limit of soil. INTRODUCTION The Atterberg limits are a basic measure of the nature of a fine-grained soil. Depending on the water content of the soil, it may appear in four states: o solid, o semi-solid, o plastic and liquid. In each state the consistency and behavior of a soil is different and thus so are its engineering properties. Thus, the boundary between each state can be defined based on a change in the soil's behavior. The Atterberg limits can be used to distinguish between silt and clay, and it can distinguish between different types of silts and clays. Shrinkage limit (SL): The shrinkage limit is the water content where further loss of moisture will not result in any more volume reduction. The shrinkage limit is much less commonly used than the liquid limit and the plastic limit. Plastic limit (PL): The plastic limit is the water content where soil starts to exhibit plastic behavior. A thread of soil is at its plastic limit when it is rolled to a diameter of 3 mm or begins to crumble. To improve consistency, a 3 mm diameter rod is often used to gauge the thickness of the thread when conducting the test. Liquid limit (LL): The liquid limit is the water content where a soil changes from plastic to liquid behavior. Casagrande subsequently standardized the apparatus and the procedures to make the measurement more repeatable. Soil is placed into the metal cup portion of the device and a groove is made down its center with a standardized tool. The cup is repeatedly dropped 10mm onto a hard rubber base during which the groove closes up gradually as a result of 14

17 the impact. The number of blows for the groove to close for 13 mm (½ inch) is recorded. The moisture content at which it takes 25 drops of the cup to cause the groove to close is defined as the liquid limit. Another method for measuring the liquid limit is the Cone Penetrometer test. It is based on the measurement of penetration into the soil of a standardized cone of specific mass. Despite the universal prevalence of the Casagrande method, the cone penetrometer is often considered to be a more consistent alternative because it minimizes the possibility of human variations when carrying out the test. The values of these limits are used in a number of ways. There is also a close relationship between the limits and properties of a soil such as compressibility, permeability, and strength. This is thought to be very useful because as limit determination is relatively simple, it is more difficult to determine these other properties. Thus the Atterberg limits are not only used to identify the soil's classification, but it also allows for the use of empirical correlations for some other engineering properties. Plasticity index (PI): The plasticity index is a measure of the plasticity of a soil. The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The PI is the difference between the liquid limit and the plastic limit (PI = LL-PL). 15

18 APPARATUS a) Liquid Limit Test Casagrande s liquid limit device 1. Balance 2. Liquid limit device (Casagrande s liquid limit device) 3. Grooving tool 4. Mixing dishes 5. Spatula 6. Oven Handle Revolution Counter Brass Cup Grooving Tools & Gauge Block b) Plastic Limit Test 1. Aluminium moisture tin 2. Glass plate 3. Mixing porcelain dish 4. Rod caliper 5. Flexible Spatula 16

19 PROCEDURES a) Liquid Limit Test 1. Determine the mass of each of the three moisture cans (W1). 2. Make sure to calibrate the drop of the cup using the other edge of the grooving tool so that there is a consistency in height of drop. 3. Put about 250 g of air dried soil passing # 40 into an evaporating dish and add a little water with a plastic squeeze bottle to barely form a paste like consistency. 4. Place the soil in the Casagrande s cup and using a spatula, smoothen the surface so that the maximum depth is about 8mm and using the grooving tool, cut a grove at the centre line of the soil pat. 5. Crank the device at a rate of 2 revolutions per second until there is a clear visible closure of 1/2 or 12.7 mm in the soil pat placed in the cup. Count the number of blows (N) that caused the closure (make the paste so that N begins with a value higher than 35). 6. If N ~ 20 to 40, collect the sample from the closed part of the pat using a spatula and determine the water content weighing the weight of the can + moist soil (W2). If the soil is too dry, N will be higher and reduces as water is being added. 7. Additional soil shouldn t be added to make the soil dry, expose the mix to a fan or dry it by continuously mixing it with the spatula. 8. Determine the corresponding w% after 24 hrs and plot the N vs w%, called the flow curve. A B C 17

20 b) Plastic Limit Test 1. Weigh the remaining empty moisture cans with their lids, and record the respective weights and can numbers on the data sheet. 2. Take a sample about 20 g of the original soil sample and add distilled water until the soil is at a consistency where it can be rolled without sticking to the hands. 3. Form the soil into an ellipsoidal mass (A). Roll the mass between the palm or the fingers and the glass plate (B). Use sufficient pressure to roll the mass into a thread of uniform diameter by using about 90 strokes per minute. The thread shall be deformed so that its diameter reaches 3.2 mm (1/8 in.), taking no more than two minutes. 4. When the diameter of the thread reaches the correct diameter, break the thread into several pieces. Knead and reform the pieces into ellipsoidal masses and reroll them. Continue this alternate rolling, gathering together, kneading and rerolling until the thread crumbles under the pressure required for rolling and can no longer be rolled into a 3.2 mm diameter thread (See Photo C). 5. Gather the portions of the crumbled thread together and place the soil into a moisture can, then cover it. If the can does not contain at least 6 grams of soil, add soil to the can from the next trial (See Step 6). Immediately weigh the moisture can containing the soil, record its mass, remove the lid, and place the can into the oven. Leave the moisture can in the oven for at least 16 hours. 6. Repeat steps three, four, and five at least two more times. Determine the water content from each trial by using the same method used in the first laboratory. Remember to use the same balance for all weighing. A B C 18

21 RESULTS Liquid Limit Determination Sample No Moisture can and lid number M C = Mass of empty, clean can + lid (g) M CMS = Mass of can, lid and moist soil (g) M CDS = Mass of can, lid and dry soil (g) M S = Mass of soil solids (g) M W = Mass of pore water (g) w = Water content (%) No. of drops (N) Plastic Limit Determination Sample No Moisture can and lid number M C = Mass of empty, clean can + lid (g) M CMS = Mass of can, lid and moist soil (g) M CDS = Mass of can, lid and dry soil (g) M S = Mass of soil solids (g) M W = Mass of pore water (g) w = Water content (%) 19

22 CALCULATIONS a) Liquid Limit Analysis 1. Calculate the water content of each of the liquid limit moisture cans after they have been in the oven for at least 16 hours. 2. Plot the water content (w) versus number of drops, N, (on the log scale). Draw the best-fit straight line through the plotted points and determine the liquid limit (LL) as the water content at 25 drops. b) Plastic Limit Analysis 1. Calculate the water content of each of the plastic limit moisture after they have been in the oven for at least 16 hours. 2. Compute the average of the water contents to determine the plastic limit (PL). 3. Calculate the plasticity index PI = LL - PL. Report the liquid limit, plastic limit and plasticity index to the nearest whole number, omitting the percent designation DISCUSSIONS (Include a discussion on the result noting trends in measured data, and comparing measurements with theoretical predictions when possible. Include the physical interpretation of the result, the reasons on deviations of your findings from expected results, your recommendations on further experimentation for verifying your results, and your findings.) CONCLUSION Comment on the objective and the results obtained from the experiment 20

23 EXPERIMENT 3 CONSTANT HEAD PERMEABILITY TEST (PREPARED BY : NURUL HUDA HASHIM) 1.0 OBJECTIVE The constant head permeability test is used to determine the permeability of samples of coarse-grained soils. 2.0 INTRODUCTION The permeability of soil is a measure of its capacity to allow the flow of water through the pore spaces between solid particles. The degree of permeability is determined by applying a hydraulic pressure gradient in a sample of saturated soil and measuring the consequent rate of flow. The coefficient of permeability is expressed as a velocity. The fundamental description of permeability is based on the equation q=va which takes the familiar form similar to river discharge. The variable q is the discharge (Vol/Time), v is the apparent velocity, and A is the area that is related to the geometry of the situation. Now, Darcy's Law describes the factors important in determining the value of v, which is v=ki where k is a constant for the material and is called the coefficient of permeability, and i is the hydraulic gradient which is related to the water pressure. The following table lists some soil permeabilities: Soil Permeability Coefficient, k (cm/sec) Relative Permeability Coarse gravel >10-1 High Sand, clean Medium Sand, dirty Low Silt Very Low Clay <10-7 Impervious 21

24 There are several factors that affecting permeability such as particle size distribution, particle shape and texture, mineralogical composition, voids ratio, degree of saturation, soil fabric, nature of fluid, type of flow and temperature. For instance, the permeability of a granular soil is influenced by its particle size distribution, and especially by the finer particles. The smaller the particles, the smaller the voids between them, and therefore the resistance to flow of water increases (i.e. the permeability decreases) with decreasing particle size. Another example is the effect of particle shape and texture. Elongated or irregular particles create flow paths which are more tortous than those around nearly spherical particles. Particles with a rough surface texture provide more frictional resistance to flow than do smooth-textured particles. Both effects tend to reduce the rate of flow of water through the soil, i.e. to reduce its permeability. Figure 2.0 : Constant head permeability test 22

25 A h 1 h 2 h 3 C B F D Ls E Thermometer Clock Datum Q Figure 2.1 : Principle of constant head permeability test upward flow 3.0 TEST EQUIPMENT 1. A permeameter cell. 2. A vertically adjustable reservoir tanks. 3. A supply of clean de-aerated water. 4. Filter material to be placed at end of permeameter. 5. Measuring cylinders of 1000 ml or 500 ml. 6. A calibrated thermometer reading to 0.5 C. 7. A stopwatch. 23

26 4.0 PROCEDURE 1. Filled the water into tank using water pipe A until full. 2. Place the soil into cylinder pot and compact it. Make sure, the soil sample in wet condition. 3. Flow the water through valve B for filling the water into cylinder pot and also into capillary glass. 4. Wait until a reading of water level on the capillary D, E and F become a stable. Record that reading and the temperature of water, T o C. 5. When the experiment in progress, make sure valve B is always open, so it will allow the water to flow into the cylinder. 6. Water flows out from the top of cylinder into the beaker. When the water over flow, collect that water using measuring cylinder. Then, every 10 second measure it. Assume that 1mL = 1cm 3 7. Water level from capillary will be changed. Measure h 1, h 2 and h 3 from datum. 24

27 5.0 RESULTS Data sheets: Diameter of sample, D = cm Length of sample, Ls = cm Radius, r = cm Area of sample, A = cm 2 Volume of sample, V = cm 3 k T = QL hat k 20 = μ T k T μ 20 k = coefficient of permeability (cm/s) Q = volume of water discharged during test (cm 3 ) L = length between manometer outlets (cm) A = cross-sectional area of specimen (cm 2 ) t = time required for quantity Q to discharge during test (s) h = difference in manometer levels during test (cm) Test Time of collection, t (s) Temperature, T ( C) Volume of water, Q (cm 3 ) Initial head, h 1 (cm) Final head, h 2 (cm) Final head, h 3 (cm) Head difference, h (h1-h2) (cm) Head difference, h (h2-h3) (cm) Avg head difference, h avg (cm) Length of sample, L s (cm) Area of sample, A (cm 2 ) Coefficient of permeability, k T (cm/s) Coefficient of permeability at 20 C, k 20 Average, k 20 25

28 Table 1 : Variation of some properties of water with temperature Temperature Density, ρ Viscosity, μ Kinematic Surface Vapour Bulk ( C) (kg/m 3 ) (m 2 /m/s viscosity, ν tension, σ pressure modulus of elacticity, (m 2 /s) (N/m) head, K p v /pg (m) (MN/m 2 ) (x10 3 ) (x10-6 ) 7.62 (x10-2 )

29 6.0 QUESTIONS 1. Plot graph coefficient of permeability (k) versus hydraulic gradient (i) in the specimen. 2. Calculate the coefficient of permeability, k for each specimen. 3. Correct the coefficient of permeability measured to that for 20 C. This is done by means of a chart that is in the laboratory. 4. Explain what you understand with the coefficient of permeability obtained from the experiment. 5. How can you relate the coefficient of permeability with the soil classification? 7.0 DISCUSSIONS (Include a discussion on the result noting trends in measured data, and comparing measurements with theoretical predictions when possible. Include the physical interpretation of the result, the reasons on deviations of your findings from expected results, your recommendations on further experimentation for verifying your results, and your findings.) 8.0 CONCLUSION (Base on data and discussion, make your overall conclusion) 27

30 1.0 OBJECTIVE EXPERIMENT 4 STANDARD PROCTOR COMPACTION TEST (PREPARED BY : MUHAMMAD MUNSIF AHMAD) To obtain the maximum dry density and the optimum moisture content. 2.0 INTRODUCTION Compaction of soil is the process by which the solid soil particles are packed more closely together by mechanical means, thus increasing the dry density, (Markwick, 1994). It is achieved through the reduction of air voids in the soil. At low moisture content, the soil grain is surrounded by a thin film of water, which tends to keep the grains apart even when compacted. In addition of more water, up to certain point, more air to be expelled during compaction. At that point, soil grains become as closely packed together as they can, that is at the dry density is at its maximum. When the amount of water exceeds that required to achieve this condition, the excess water begin to push particles apart, so the dry density reduced. The optimum water content is the water content that results in the greatest density for a specified compactive effort. Compacting at water contents higher than (wet of ) the optimum water content results in a relatively dispersed soil structure (parallel particle orientations) that is weaker, more ductile, less pervious, softer, more susceptible to shrinking, and less susceptible to swelling than soil compacted dry of optimum to the same density. The soil compacted lower than (dry of) the optimum water content typically results in a flocculated soil structure (random particle orientations) that has the opposite characteristics of the soil compacted wet of the optimum water content to the same density. 28

31 3.0 TEST EQUIPMENT 3.1 Clylindercal metal mould 3.2 Metal rammer with 50mm diameter face weighing 2.5 kg mm BS sieve and receiver 3.4 Measuring cylinder 3.5 Moisture cans 3.6 mixing pan 3.7 Electronic balance 3.8 Jacking apparatus 3.9 Drying oven 3.10 Straight edge 3.11 Trowel 4.0 PROCEDURES 4.1 Determine the weight of the mould body (not the extension) by using the balance and record the weights, m1 (g). Measure its internal diameter (D) mm and length (L) mm in several places and calculate the mean dimensions. 4.2 Apply with an oily cloth on the internal surface of mould to ease the removal of soil later on. 4.3 Measure the empty pan mixing and ±5 kg of dried soil sample that has passing through sieve (20 mm). 4.4 Place the mould assembly on a solid base, such as concrete floor. 4.5 Pour the moist soil into the mold in three equal layers. Each layer should be compacted uniformly by the standard Proctor hammer 25 times before the next layer of loose soil is poured into the mold. Note: do not attempt to grab the lifting knob before the rammer has come to rest. The sequence as shown in Figure 4.0 has to be followed. Repeat for the second and third layer that the final layer shall not more than 6 mm above the mould body. 29 Figure 4.0: sequence of blows using hand rammer

32 4.6 Remove the top attachment from the mold. Be careful not to break off any of the compacted soil inside the mold while removing the top attachment. 4.7 Using a straight edge, trim the excess soil above the mold (Fig. 4.1). Now the top of the compacted soil will be even with the top of the mold. Figure 4.1: Excess soil being trimmed 4.8 Determine the weight of the mould + base plate + compacted moist soil in the mould, m2 (g). 4.9 Remove the base plate from the mould. Using a jack, extrude the compacted soil cylinder from the mould Take a moisture container and determine its mass, w 0 (g) From the moist soil extruded in (Step 4.9), collect a moisture sample in the moisture can (Step 4.10) (preferable one each layer). This must do immediately before the soil dry out and determine the mass of the container + moist soil, w 1 (g) Place the moisture container with the moist soil in the oven to dry to a constant weight Break the rest of the compacted soil by hand and mix it with the left- over moist soil in the pan. Repeat Steps 4.5 through Add more water and mix it to raise the moisture content, approximately as follows : Sandy and gravelly soils: 1-2% ( ml of water to 5 kg of soil) Cohesive soils: 2-4% ( ml of water to 5 kg of soil) 4.14 After 24 hrs recover the sample in the oven and determine the weight w 2 (g). 30

33 5.0 SAMPLE CALCULATION 5.1 Calculate the bulk density, ρ of each compacted specimen from the equation m m Mg m / if volume = 1000 cm 3 Where: m1 mass of mould; m2- mass of soil and mould m m Mg m V 2 1 / 3 if volume = V cm 3 2 V DL (check all conversion of unit) Calculate moisture content, w n% for each compacted specimen. w n w w w w Where: w 0 weight of empty container, w 1 weight of dry soil + container, w 2 weight of moist soil + container 5.3 Calculate the average value of moisture content, w% for each compacted specimen. w w w w Calculate corresponding dry density, ρ d d w Mg/m 3 31

34 5.5 Plot of graph dry density, ρ d against moisture content, w. draw a smooth curve through the points. 5.6 Plotting Of Air Voids Line, V a V a = 0%, 5% and 10% (use G s = ρ s = 2.65) w a assumed water contain. Use the equation below using ρ w = 1Mg/m 3 d Va Mg / m 1 wa 100 s 3 32

35 6.0 RESULTS 6.1 Test Criteria Test Method: Date Tested: Tested By: Project Name: Sample Number: Visual Classification of Soil: 6.2 Density Calculation Volume Of Cylinder Mould = Measurement No Mould + soil (g) Mould (g) Soil mass (g) Wet density, ρ 6.3 Moisture Content Measurement No Assumed water contain w a (%) Wet soil + container (g) Dry soil + container (g) Empty container (g) Moisture content, wn (%) Average Moisture, w% 33

36 6.4 Dry Density Calculation (Use Actual Volume Of Cylinder) Measurement No Actual Avg Moisture, w% Dry Density, ρd 7.0 DISCUSSION/ EVALUATION/ EXERCISES a) Calculate the wet density in gram per cm 3 of the compacted soil sample by dividing the wet mass by the volume of the mold used. b) Calculate the moisture content of each compacted soil specimen by using the average of three water contents. c) Compute the dry density using the wet density and water content determined in step 7.2. d) Using the tabulated data table, plot the graph of Dry Density against Moisture content. Attach the graph to your answer sheet. e) On the same graph, plot the Air Voids Line, V a = 0%, 5% and 10%. Show the calculation. f) Identify and report the optimum moisture content of compaction used on data sheet. g) Define and explain what is meant by optimum moisture content? h) State the problem factors that affect the accuracy of experiment? 8.0 CONCLUSION Comment on the objective and the results obtained from the experiment 34