Embed Size (px)
Citation preview
TABLE OF CONTENTS
EXPERIMENT NO. 1(A)................................................................................................................2
WATER CONTENT DETERMINATION (BY OVEN DRYING METHOD)......................................2
EXPERIMENT NO. 1(B)................................................................................................................6
WATER CONTENT DETERMINATION (BY SPEEDY MOISTURE METER)...............................6
EXPERIMENT NO. 2.....................................................................................................................9
SPECIFIC GRAVITY DETERMINATION.......................................................................................9
EXPERIMENT NO. 3(A)..............................................................................................................13
PARTICLE SIZE ANALYSES (MECHANICAL ANALYSIS).........................................................13
EXPERIMENT NO. 3(B)..............................................................................................................19
PARTICLE SIZE ANALYSES (HYDROMETER ANALYSIS).......................................................19
EXPERIMENT NO. 4...................................................................................................................30
DETERMINATION OF ATTERBERG’S LIMITS (LIQUID LIMIT AND PLASTIC LIMIT)..............30
EXPERIMENT NO. 5(A)..............................................................................................................35
COMPACTION TEST (STANDARD AASHTO)...........................................................................35
EXPERIMENT NO. 5(B)..............................................................................................................40
COMPACTION TEST (Modified AASHTO)..................................................................................40
EXPERIMENT NO. 6(A)..............................................................................................................43
DETERMINATION OF IN-PALCE SOIL DENSITY (CORE CUTTER METHOD)........................43
EXPERIMENT NO. 6(B)..............................................................................................................46
DETERMINATION OF IN-PALCE SOIL DENSITY (SAND REPLACEMENT METHOD)............46
APPENDIX
(RELEVANT ASTM STANDARDS)
EXPERIMENT NO. 1(A)
WATER CONTENT DETERMINATION (BY OVEN DRYING METHOD)
OBJECTIVE
To determine the amount of water or moisture present in the given quantity of soil in terms of its dry weight.
NEED AND SCOPE OF THE EXPERIMENT
In almost all soil tests natural moisture content of the soil is to be determined. The knowledge of the natural moisture content is essential in all studies of soil mechanics. To sight a few, natural moisture content is used in determining the bearing capacity and settlement. The natural moisture content will give an idea of the state of soil in the field.
THEORY
Water content or moisture content determination is a routine laboratory test, the results of which are used in evaluation of different important engineering properties of soil. The determination of moisture content involves removing of soil moisture by oven-drying a soil sample until the weight remains constant. The moisture content is expressed in percentage and is calculated from the sample weight before and after drying.
Mathematically it can be written as;
ω=Ww
W s×100
Ww = Weight of Soil WaterWs = Weight of Soil Solids
APPARATUS
1. Moisture tins2. Weighing balance (Least count of 0.01 grams)3. Drying oven (temperature control at 110 ± 5 OC)
PROCEDURE
1. Take empty, clean moisture tin and mark it with an identifying number or code.2. Weigh the container and record the weight as W1 to the nearest 0.01 grams.3. Take representative wet soil sample (not less than 20 grams) and place it quickly in the
moisture tin.4. Weight the moisture tin with wet soil sample to the nearest 0.01 gram and record this weight
as W2.
5. Place the moisture tin with the wet soil sample in drying oven at constant temperature of 110 ± 5 OC for 24 hours.
2
6. After 24 hours remove the moisture tin from drying oven and weigh it to the nearest 0.01 gram. Record this weight as W3.
3
PRECAUTIONS
1. If it is not possible to place the container carrying wet soil sample in drying oven immediately, cover the container with lid.
2. If it is suspected that gypsum is present in the soil, the soil sample should not be subjected to a temperature beyond 60 oC. Otherwise gypsum will lose its water of crystallization affecting thereby the results of moisture content. Oven drying at 60 oC may, however, be continued for a longer time in order to ensure complete evaporation of free water present in the sample.
OBSERVATIONS AND CALCULATIONS
ω=Ww
W s×100=
W 2−W 3
W 3−W 1×100
Where;
W1 = Weight of tin = (grams)
W2 = Weight of moist soil + tin = (grams)
W3 = Weight of dried soil + tin = (grams)
Can No.
Wt. of wet soil + can (grams)
Wt. of dry soil + can (grams)
Wt. of can (grams)
Wt. of dry soil (grams)
Wt. of moisture (grams)
Water content (%)
No. of blows
REFERENCE
ASTM D2216-98Standard test method for laboratory determination of water (moisture) content of soil and rock by mass.
4
MoistureContent ,ω=¿
COMMENTS
5
EXPERIMENT NO. 1(B)
WATER CONTENT DETERMINATION (BY SPEEDY MOISTURE METER)
OBJECTIVE
To determine moisture content of a soil sample by speedy moisture meter.
THEORY
The speedy moisture meter provides a quick, simple means of determining the moisture content of soil. It is particularly useful for field determinations of moisture contents in conjunction with the field compaction testing. The speedy moisture meter is also known as calcium carbide gas moisture tester.
The basic principle behind this method is that the free moisture in the soil reacts with calcium carbide reagent to form a gas called acetylene gas. This gas exerts a pressure on the internal side of the walls of speedy moisture meter which is reflected by a pressure dial. The pressure dial is calibrated in such a way that pressure reading reflects the percent moisture by wet weight of soil directly. The reaction which takes place inside the speedy moisture meter is as follows;
CaC2 + H2O CaO + C2H2
Since the moisture content by definition is expressed as a percentage of dry weight of soil, the readings obtained by speedy moisture meter are corrected using following expression;
ω=ωsp
(1−ωsp)×100
Where;
ω = Moisture content in percentage of dry weight of soil
ωsp = Moisture content as obtained by speedy moisture meter expressed as decimal fraction
APPARATUS
1. Speedy moisture meter2. Calcium Carbide reagent3. Two (02) 1.25 inch steel balls4. Cleaning brush and cloth5. Scoop for measuring calcium carbide reagent
PROCEDURE
1. Weigh approximately 6 grams of wet soil sample on the tarred scale, and place it in the cap of the tester.
6
2. Place three (03) scoops of calcium carbide and two (02) 1.25 inch steel balls in the larger chamber of the moisture tester.
3. With the pressure vessel in an approximate horizontal position, insert the cap in the pressure vessel and seal it by tightening the clamp.
4. Raise the moisture tester to a vertical position so that the soil in the cap falls into the pressure vessel.
5. Shake the instrument vigorously so that all lumps are broken up to permit the calcium carbide to react with all available free moisture. The instrument should be shaken with a rotating motion so that the steel balls do not damage the instrument or cause soil particles to become embedded in the orifice leading to pressure diaphragm.
6. When the needle stops moving, record the dial reading while holding the instrument in a horizontal position at eye level.
7. With the cap of the instrument pointed away from the operator, slowly release the gas pressure. Empty the pressure vessel and examine the material for lumps. If the sample is not completely pulverized, the test should be repeated using a new wet soil sample.
8. Apply correction to the dial reading to convert the moisture content in terms of dry weight of soil.
7
LIMITATION
The speedy moisture meter can determine the moisture content only upto 20 percent. If the moisture content of the sample exceeds the limit of the pressure gauge, one half size sample must be used and dial gauge reading must be doubled. PRECAUTIONS
1. Care should be taken that no calcium carbide comes in contact with the soil until a complete seal is achieved.
2. Shake the instrument by rotating the instrument in horizontal plane so that moisture tester is not damaged during shaking.
3. After completion of test, slowly release the gas pressure pointing the instrument away from operator.
OBSERVATIONS AND CALCULATIONS
ω=ωsp
(1−ωsp)×100
ωsp =
Sample No.
ωsp (%)
ω (%)
COMMENTS
8
MoistureContent ,ω=¿
EXPERIMENT NO. 2
SPECIFIC GRAVITY DETERMINATION
OBJECTIVE
To familiarize the students with general method of obtaining the specific gravity of a mass of any type of material composed of small particles (specifically soil).
THEORY
A value of specific gravity is necessary to compute the void ratio of a soil, it is used in the hydrometer analysis, and it is useful to predict the unit weight of a soil. Occasionally, the specific gravity may be useful in soil mineral classification; e.g., iron minerals have larger value of specific gravity than silicas.
The specific gravity of any substance is defined as the unit weight of the material divided by the unit weight of distilled water at 4 oC. Thu, specific gravity of soil can be found as;
Gs=γ soilγwater
As long as equal volume of water and soil are involved, the above stated form can be simplified as;
Gs=W soil/VW water/V
Strictly speaking above mentioned equation is only valid if we do not consider any density change with temperature. However, a slight increase in precision to account for temperature effects on the density of water can be obtained by rewriting above stated equation as;
Gs=W soil
W water×α
Where, α is the ratio of the unit weight of water at temperature T of the test and at 4oC. The value of Gs obtained at temperature T (which will be too large if T > 4oC) is appropriately reduced.
α=γ Tγ 4oC
APPARATUS
1. Pycnometer2. Weighing balance (Least count of 0.01 grams)3. Thermometer
9
4. Hot plate or Bunsen burner5. Funnel6. Drying oven7. Paper towel
PROCEDURE
1. Weigh the dry pycnometer to nearest 0.01 gram and record it as W1.2. Take about 100 grams of oven dried soil and put it into the flask. Weigh the flask and dry soil
to the nearest 0.01 gram. Record this weight as W2.3. Add water in the pycnometer until it is about two-third full. In order to remove the entrapped
air from soil and water, heat the mixture for at least 2 h after the soil-water mixture comes to a full boil. Use only enough heat to keep the slurry boiling. Agitate the slurry as necessary to prevent any soil from sticking to or drying onto the glass above the slurry surface.
4. Allow the mixture to cool, and then fill the flask with distilled water to above the calibration mark.
5. Place the stopper in the bottle while removing the excess water. Be sure the entire exterior of the flask is dry. Weigh the flask to the nearest 0.01 gram and record this weight as W3.
6. Empty the flask, wash it thoroughly and fill it completely with water. Dry the exterior of the flask. Weigh the flask and record it as W4.
7. Repeat the procedure three times.8. Record the temperature of soil water mixture.
10
Gs=(W 2−W 1)α
[ (W 4−W 1 )−(W 3−W 2)]PRECAUTIONS
1. Make sure no air is entrapped within the soil water mixture.2. Weights should be obtained from a properly balanced weighing scale.
OBSERVATIONS AND CALCULATIONS
Test No. 1 2 3
Volume of flask
W1 (grams)
W2 (grams)
11
Water
W4
Water
SoilW3
SoilW2W1
W3 (grams)
W4 (grams)
α
Gs
Typical values of correction factor, α;
T (oC) Correction Factor, α4 1.000015 0.999920 0.998225 0.997130 0.995735 0.9941
REFERENCE
ASTM D854 – 02Standard test methods for specific gravity of soil solids by water pycnometer.
12
COMMENTS
13
EXPERIMENT NO. 3(A)
PARTICLE SIZE ANALYSES (MECHANICAL ANALYSIS)
OBJECTIVE
To introduce the students to the method of making a mechanical grain size analysis of a soil and presenting the resulting data.
THEORY
Grain size analysis carries much importance in determination of engineering properties of soil e.g. suitability criteria of soils (for road, airfield, levee, dam and foundation material), soil water movement, susceptibility to frost action etc.
The grain size analysis is the attempt to determine the relative proportions of the different grain sizes which make up soil mass. For this, sample should be statically representative of the soil mass.
By carrying out mechanical analysis, particle sizes and their relative distribution can be done for the particle greater than 0.075 mm. The mechanical analysis is carried out by stacking the sieves, one on top of the other, pouring a known weight of soil into the top sieve on the stack, and shaking the sieve in a certain manner to allow the soil to fall down through the stack.
The stack of sieves is known as nest of sieves. The nest is arranged with the largest screen openings (smallest sieve number) on top, progressing to the sieve with the smallest screen opening (largest sieve number) on the bottom of the nest. A lid is placed on the top of the nest and pan is placed below the bottom sieve to catch any soil that passes through the smallest opening. The number or the sizes of the sieves used in the nest depends on the type of the soil and the distribution of the particle sizes. Generally sieve No. 4, 10, 40, 100, 200 are used for classifying the soil.
APPARATUS
1. A set of sieves2. Mechanical soil pulverizer3. Weighing balance (Least count = 0.01 grams)4. Mechanical sieve shaker
PROCEDURE
1. Obtain 500 grams of soil sample which has already been pulverized by placing it on sieve No. 200 and then oven dried.
2. Arrange a nest of sieves including sieves No. 4, 10, 40, 50, 100, 200, pan.3. Place the set of sieves in the mechanical sieve shaker and sieve it for 5 to 10 minutes. Note
that if the entire set of sieves does not fit into the shaker perform a hand shaking operation
14
until the top few sieves can be removed from the stack and then place the remainder of the stack in the mechanical shaker.
4. Remove the nest of sieves from the shaker and obtained the weight of the material retained on each sieve. Sum these weights and compare with the actual weight taken. A loss of more than 2 percent by the weight of the residual material is considered unsatisfactory and the test should be replaced.
5. Compute the percent retained on each sieve by dividing the weight retained on each sieve by the original sample weight.
6. Compute the percent passing by starting with 100 percent and subtracting the cumulative percent retained for that sieve.
15
OBSERVATIONS AND CALCULATIONS
Weight of sample = __________ grams
Sieve No. Diameter(mm)
Weight of Soil Retained (grams)
PercentageWeight
Retained(%)
Cumulative Percent
Retained(%)
Percent Passing
(%)
16
0.0010.010.111010010000
10
20
30
40
50
60
70
80
90
100Grain Size Distribution Curve
Grain Size (mm)
Perc
ent
Fine
r by
Wei
ght
(%)
D10 = D30 = D60 =
C c=(D60)(D10)
=¿
C c=(D30)
2
(D10)×(D60)=¿
PRECAUTIONS
1. Particles that appear to be stuck in the sieve screen should never be forced on through the mesh. There are two reasons for not doing this.
a) The particles would have passed the screen on their own had they been smaller than the mesh opening. Forcing these particles through the screen to be retained on the next size would distort the grain size results.
b) Secondly forcing the particles through the mesh can damage the screen and necessitate its replacement.
Particles caught in a screen should be removed by brushing with the proper sieve brush. Brushing should be done from the underside of the screen in order that the particles can be brushed out of the screen in the direction from which it entered in the screen opening. Stubborn (obstinate) particles that cannot be removed by rushing should be left in place.
2. Lumps of soils must have broken down into their individual particles in order for the grain size analysis to be valid. This is accomplished in two ways. The first is to break up lumps with a rubber-tipped pestle in ceramic mortar. It has been found that the rubber-tipped pestles will not grind or crush the individual particles while a ceramic or metal-tipped pestle will. The second is to wet-sieve the soil. Washing the particles that are retained on the No.200 sieve with water and this will accomplish two things.
a) It separates those small lumps that might not have been broken up with the rubber tipped pestle into individual particles.
b) It washes the “Dust size” particles and through the No.200 sieve.
3. A 10 minute shaking period is suggested in procedure. A large sample is requires longer shaking than a sample. Similarly a sample comprising primarily of fine grained material will require a longer shaking period than a coarse grained sample of equal weight.
REFERENCE
ASTM D422Standard test method for particle-size analysis of soils
COMMENTS
19
EXPERIMENT NO. 3(B)
PARTICLE SIZE ANALYSES (HYDROMETER ANALYSIS)
OBJECTIVE
The hydrometer method is used to approximate the particle size distribution for particles that passes sieve #200. The hydrometer test is held as an extension to the sieve analysis to make us able to classify the soil.
THEORY
Hydrometer test is based on the principle that grains of different sizes fall through a liquid at different velocities. The essence of this concept is that sphere falling through a liquid will reach a terminal velocity expressed by Stock’s Law;
v=2 γs−γw9η
×( D2 )2
………. (Eq .1)
v = Velocity of fall of sphere, cm/ secγs = Unit weight of soil, g/ ccγw = Unit weight of water, g/ ccη = Absolute viscosity of the fluid, dyne –sec/ sq. cmD = Diameter of spheres, cm
The equation mentioned above is only valid for diameter approximately ranging from 0.0002 to 1 mm as large grains cause excessive fluid turbulence and very small grains are subjected to Brownian movement (i.e. subject to particle forces of attraction and repulsion).
For determination of diameter above mentioned equation can be written as;
D= 18ηvγs−γw
……….(Eq .2)
The accuracy of using this equation to determine soil particle sizes is subjected to how well some assumptions made to permit using stokes equation actually apply to the test conditions. Some of these assumptions are;
1. Stocks equation was developed using a sphere, whereas most silt and particularly clay particles are platy shaped.
2. Stocks equation was developed using only a single sphere, but a great many particles are involved in even a sample as small as 50 grams of soil.
3. The specific gravity of stokes sphere was accurately known, but the specific gravity of the soil solids is actually an average value of all minerals comprising the particular soil being tested.
20
4. Clay particles have a tightly bounded layer of adsorbed water that remains with the parcel as it falls through the water column in the hydrometer bottle. Thus a great resisting surface than that of the clay particle alone is in effect as the particle falls through the suspension.
To obtain the velocity of fall of the particles, the hydrometer is used. This is a device originally develop to read the specific gravity of a solution, but by altering the scale it can be made to read other values.
The hydrometer is usually a type 152 H (ASTM designation) and is calibrated to read grams of soil of value Gs = 1.65 in 1.000 cu-cm of suspension as long as no more than 60 grams of soil is involved. The reading is of course, directly related to the specific gravity of the solution. This particular hydrometer calibration is a considerable aid in the computations. For this reason, this type of hydrometer is widely used although other hydrometer can also be used.
The hydrometer displays the specific gravity of the soil water suspension at the centre of its bulb as shown.
Any soil grains larger than those still in suspension in the zone L (the distance between the centre of the volume of the bulb and the water surface) have fallen below the centre of volume, and the constantly decrease the specific gravity of the suspension at constant weight, the less the specific gravity of the suspension, the deeper the hydrometer will sink into the suspension (the larger the distance L will become). For water the specific gravity (or density) decreases as the temperature rises from 4oC. This also will cause the hydrometer to sink deeper into the suspension.
Since ‘L’ represents the distance the particles fall in some time t, and the velocity term in Eq. 2 is distance divided by time, it is evident that the velocity of the fall of the particle is;
21
v=Lt
Thus it is necessary to find ‘L’ corresponding to some elapsed time ‘t’ so that the velocity for use in stokes equation can be found.
Fig. b shows the jar containing the soil suspension. When the hydrometer is immersed in the jar (Fig. c), the water level aa rises to a1a1. The rise is equal to the volume V1 of the hydrometer divided by the internal area of cross-section A of the jar. Similarly the level bb rises to b1b1. Where bb is the level situated at depth L below the top level aa at which the density measurement of the soil suspension are being taken. The rise between bb and b1b1
will be approximately equal to Vb/2A. The level b1b1 is now corresponding to the centre of the bulb, but the soil particles at b1b1 are of the same concentrations as they were at bb. Therefore we have,
L=(L1+L22
+V b
2 A−V b
A)
or
L=L1+12 (L2−V b
A )………. Eq .3
The hydrometer reading must not be corrected for use in Eq. 3 except for meniscus (in turbid suspension, one must read the top of the meniscus).
If the particle diameter and percentage of soil remaining in suspension are known which in this case is also the percent finer sufficient data are available to plot a grain size distribution curve.
The percent finer is related directly to hydrometer reading of the 152 H hydrometer since it reads grams of the soil still in suspension directly if the unit weight of type soil grains 2065 gm/cu-cm and the density of the water is 1. Since a dispersing agent has been used, this is not likely to occur often the temperature is likely to occur often the temperature is likely to be around 20oC and the Gs of the soil may not be 2065-corrections must therefore be applied to the actual hydrometer reading to make it accurately read the grams of the soil still in suspension. To keep temperature a single valued variable, it is convenient to use a water tub to maintain a constant temperature value for the duration of the test. To obtain the effect of water and dispersing agent on the hydrometer reading, it is convenient to use a standard jar of clear water with the same quantity of dispersing agent as used in the soil suspension to obtain a zero reading( a zero correction value ) at the same temperature as the soil water suspension. A reading of less than zero (i.e. a minus reading) is possible but all zero reading should be to the top of the meniscus. If the temperature is too high in both the soil and standard suspension, obviously the density of water is decreases equally in both suspensions and the hydrometer sinks too deep, but this is directly a function of the temperature of the suspension and thus one has a temperature correction C t which can be obtained once for all, from table.
22
Since deeper the hydrometer sinks, smaller the reading R regardless of the amount of the soil in suspension, corrections must be applied to the actual reading which accurately measures the soil in suspension to make a percent finer computation.
Rc=Ractual−ZeroCorrection+C t……….Eq .4
After correct hydrometer reading has been obtained, the percent finer can be computed by simple proportion (if Gs = 2.65) as
Percent finer=Rc
W s×100 percent………. Eq .5
Rc = Corrected hydrometer reading (grams of the soil in suspension at some elapsed time t)Ws = weight of the original soil sample placed in suspension gm.
If Gs is not equal to 2.65, the a multiplier ‘a’ is computed to use with Eq. 5 by proportion as follows
aGs /(G s−1)
= 12.65/ (2.65−1)
Solving for ‘a’ one obtains;
a=Gs(1.65)/{(G s−1 )2.65 }
The percent finer when Gs ≠ 2.65, is computed as percent finer = (Rc . a/Ws) 100 percent.
Typical values of ‘a’ are given in table-2.
For computation purposes Eq. 2 is usually written using ‘L’ in centimeters and ‘t’ in minutes to obtain ‘D’ in millimeters as follows;
D=√{ 30η980 (Gs−Gw) }L /t m.m
Which can be even simplified further to;
D=k √L/ t
Value of k can be obtained from table 5.
PRETREATMENT OF SOIL
By mixing a given quantity of soil with water and a small amount of dispersing agent to form a 1,000 Cu-Cm quantity of solution, a solution with a specific gravity larger than one is obtained (since w of water is 1 at 4C). The dispersing also called deflocculating agent) is
23
added to neutralize the charges on the smaller soil grains, which often have plus or minus charges. With proper orientation, these charged soil grains will be attracted to each other with sufficient force to remain stuck together, thus creating larger particles. According to Stokes law, these large particles will settle faster through the fluid then the smaller particles.
Following is the procedure as adopted by Soil Engineers in England;
100gm of soil is first treated with about 100ml of 6 percent hydrogen peroxide solution until gas bubbles are no longer given off (this removes organic materials. This treatment may take several days and require additional hydrogen peroxide. Next the soil is treated with about 100 ml of 0.2 N hydrochloric acid to remove any calcium compounds which might decompose during the test. The treatment is continued until the soil gives an acid reaction to litmus. The soil is now ready to use and about 50gm of treated damp soil is mixed with 250ml of solution containing 8 gm of sodium oxalate (Na2C2O4) per 1,000 Cu-Cm as a dispersing agent. Sodium oxalate yields an alkaline solution, thus the soil water suspension is being neutralized with the addition of the material. The soil mixture with sodium oxalate is then mixed in the malt mixer for 15 min, the contents transferred to the sedimentation cylinder and the test is performed.
APPARATUS
1. Sedimentation cylinder (1,000 cu-Cm cylinder) also termed a hydrometer jar.2. Hydrometer (152 H)3. Soil-dispersion device (malt mixer)4. Dispersion agent (sodium hexametaphosphate NaPO3), trade name calgon, or
sodium silicate (Na2Sio3) also called water glass.5. Thermometer
PROCEDURE
1. Take exactly 50gm of oven-dry well pulverized soil and mix with 125 Cu-Cm of 4 percent sodium metaphosphate solution.
2. Allow the mixture to stand for about 1 hr (ASTM suggests 16hr for clayey soils). Transfer the mixture to malt mixer cup and add tap water until the cup is two-third full. Mix for 3 to 10 minutes.
3. Transfer all the contents of the cup to the sedimentation cylinder, being careful not to lose any material. Add tap water to fill the cylinder to the 1,000 Cu-Cm mark.
4. Prepare a control jar of tap water with 125 cu-cm of 4 percent sodium metaphosphate solution or with same quantity of sodium silicate solution as used in step 1 above.
5. Take a No. 12 rubber stopper and cap the cylinder of soil suspension. Carefully agitate for at least 1 min.
6. Set the jar down, remove the stopper, immediately insert the hydrometer and take hydrometer readings at elapsed time of 1, 2, 3 and 4 min. also take a temperature reading.
7. Place the hydrometer and thermometer into the control jar (which should be within 1c if soil suspension).
8. Take a meniscus reading from the control jar.
24
9. Replace the No. 12 stopper and reagitate the suspension. Take another series of hydrometer readings at 1, 2, 3 and 4 min. of elapsed times.
10. Repeat as necessary until two sets of the readings agree within one unit.11. When agreement is reached within a pair of readings, once more shake the mixture
and take hydrometer readings at elapsed time of 1, 2, 3 and 4 min and compare it with the previously accepted pair of 4 min reading.
12. If good agreement is obtained, use the previously averaged pair of readings as the first four readings and collect additional hydrometer and temperature readings at elapsed time of 8, 15 and 30 minutes, followed by 1, 2, 4, 8, 16, 24 and 96 hrs.
13. Terminate the test prior to 96 hr. of elapsed time if the hydrometer readings drop below 5. The hydrometer is stored in the control jar during these series of readings except when the actual readings are being taken.
PRECAUTIONS
1. It is usual to leave the hydrometer in the soil suspension for the first 4 min, remove it and reinsert it each time for all additional readings. Little error will be caused if the hydrometer is left in the jar for all 4 of the readings as compensating errors of fluid disturbance will tend to offset errors due to soil participating on the hydrometer bulb.
2. When placing the hydrometer in the soil suspension for a reading proceed slowly enough that It takes about 10 sec. for the operation( the insertion time should not exceed approximately 5 to 6 second).
3. Consistent readings indicate a uniform mixture of soil water suspension.4. Time beyond first 2 hr. of readings are approximate and are set to give reasonable
spread of plotted points for the percent finer vs. grain size (diameter) curve.
25
Table 1: Typical values of correction factor (α)
T(⁰C) α
4 1.000015 0.999920 0.998225 0.997130 0.995735 0.9941
Table 2: Correction factor 'a' for unit weight of solids
Unit Wt. of soil Solids(g/cm3) a
2.95 0.942.90 0.952.85 0.962.80 0.972.75 0.982.70 0.992.65 1.002.60 1.012.55 1.022.50 1.032.45 1.05
Table 3: Temperature correction factor (Ct)
T(⁰C) Ct
15 -1.1016 -0.9017 -0.7018 -0.5019 -0.3020 0.0021 0.2022 0.4023 0.7024 1.0025 1.3026 1.6527 2.0028 2.5029 3.0530 3.80
26
Table 4: Values of effective depth (L) for use in Stoke's formula for diameters of particles for ASTM soil hydrometer 152H
Actual HEffective Depth,
L(cm)
Actual HEffective Depth,
L(cm)
0 16.3 31 11.21 16.1 32 11.12 16.0 33 10.93 15.8 34 10.74 15.6 35 10.55 15.5 36 10.46 15.3 37 10.27 15.2 38 10.18 15.0 39 9.99 14.8 40 9.7
10 14.7 41 9.611 14.5 42 9.412 14.3 43 9.213 14.2 44 9.114 14.0 45 8.915 13.8 46 8.816 13.7 47 8.617 13.5 48 8.418 13.3 49 8.319 13.2 50 8.120 13.0 51 7.921 12.9 52 7.822 12.7 53 7.623 12.5 54 7.424 12.4 55 7.325 12.2 56 7.126 12.0 57 7.027 11.9 58 6.828 11.7 59 6.629 11.5 60 6.530 11.4
27
Table 5: Values of k for several unit weights of soil solids and temperature combinations
T (⁰C)Unit Weight of Soil Solids (g/cm2)
2.45 2.50 2.55 2.60 2.65 2.70 2.75 2.80 2.85
16 0.01510
0.01510
0.01480
0.01460
0.01440
0.01410
0.01390
0.01370
0.01360
17 0.01511
0.01490
0.01460
0.01440
0.01420
0.01400
0.01380
0.01360
0.01340
18 0.01492
0.01480
0.01440
0.01420
0.01400
0.01380
0.01360
0.01340
0.01320
19 0.01474
0.01450
0.01430
0.01400
0.01380
0.01360
0.01340
0.01320
0.01310
20 0.01456
0.01430
0.01410
0.01390
0.01370
0.01340
0.01330
0.01310
0.01290
21 0.01438
0.01410
0.01390
0.01370
0.01350
0.01330
0.01310
0.01290
0.01270
22 0.01421
0.01400
0.01370
0.01350
0.01330
0.01310
0.01290
0.01280
0.01260
23 0.01404
0.01380
0.01360
0.01340
0.01320
0.01300
0.01280
0.01260
0.01240
24 0.01388
0.01370
0.01340
0.01320
0.01300
0.01280
0.01260
0.01250
0.01230
25 0.01372
0.01350
0.01330
0.01310
0.01290
0.01270
0.01250
0.01230
0.01220
26 0.01357
0.01330
0.01310
0.01290
0.01270
0.01250
0.01240
0.01220
0.01200
27 0.01342
0.01320
0.01300
0.01280
0.01260
0.01240
0.01220
0.01200
0.01190
28 0.01327
0.01300
0.01280
0.01260
0.01240
0.01230
0.01210
0.01190
0.01170
29 0.01312
0.01290
0.01270
0.01250
0.01230
0.01210
0.01200
0.01180
0.01160
30 0.01298
0.01280
0.01260
0.01240
0.01220
0.01200
0.01180
0.01170
0.01150
OBSERVATIONS AND CALCULATIONS
Hydrometer # =Gs =a =
Dispersing Agent =Amount =Weight of Soil, Ws =Zero Correction =Maniscus Correction =
28
29
Elap
sed
Tim
e
Tem
pera
ture
Tem
pera
ture
C
orre
ctio
n Fa
ctor
Act
ual
Hyd
rom
eter
R
eadi
ng
Cor
rect
ed
Hyd
rom
eter
R
eadi
ng
% F
iner
Hyd
. C
orre
cted
on
ly fo
r M
anis
cus
Effe
ctiv
e D
epth
(fr
om T
able
)
L / tK
(from Table)
Dia
met
er o
f Pa
rtic
les
D =
K √
(L/t)
% F
iner
by
Wei
ght
=( %
Fin
er x
Wt.
pass
ing
#200
) / 1
00
t (min) T (⁰C) Ct RoRc = Ro - Zero Correc. + Ct
% Finer = (Rc x a)/Ws
R L D (mm)
REFERENCE
ASTM D422Standard test method for particle-size analysis of soils
COMMENTS
EXPERIMENT NO. 4
DETERMINATION OF ATTERBERG’S LIMITS (LIQUID LIMIT AND PLASTIC LIMIT)
OBJECTIVE
To introduce the students to the procedure for determining the liquid and plastic limit.
THEORY
The liquid limit and plastic limit are two of the five “limits” proposed by A. Atterberg, a Swedish agricultural scientist. These limits are;
1. Cohesion limit – that moisture content at which soil crumbs just stick together.2. Sticky limit – that moisture content at which soil just sticks to a metal surface such as
spatula blade. This would have some significance to the agricultural engineer since it is related to soil sticking to the moldboard of a plow or disc in cultivating soil
3. Shrinkage limit – that moisture content below which no further soil volume reduction (or shrinkage) occurs.
4. Plastic limit – moisture content below which soil is non-plastic.5. Liquid limit – moisture content below which the soil behaves as a plastic material. At
this moisture content, the soil is on the verge of becoming a viscous fluid.
The liquid and plastic limits have been widely used all over the world, primarily for soil identification and classification. The shrinkage limit is useful in certain geographical areas where soil undergo large volume changes when going through wet and dry cycles. The cohesion and sticky limits are used very little worldwide.
APPARATUS
1. Liquid limit device with Casagrande grooving tool (cuts a groove of size 2 mm wide at the bottom, 11 mm wide at the top and 8 mm high).
2. No. 40 ASTM sieve3. Water content equipment4. Spatula5. Glass plate6. 1/8 inch diameter brass rod7. Containers
PROCEDURE FOR LIQUID LIMIT DETERMINATION
1. Pulverize a sufficient quantity of air-dried soil to obtain about 250 grams of representative sample passing through No. 40 sieve.
2. Adjust the height of fall of the liquid limit device to exactly 1 cm. Use the 1 cm calibration block at the end of the grooving tool for making this adjustment.
32
3. Place about 250 grams of soil in a glass plate, (or container). Add distilled water very slowly and using spatula mix the soil thoroughly until it becomes a thick, homogeneous paste. Be careful not to add too much water. Add approximately that much water in the soil to make it such consistent that a blow count of 30 to 40 blows to close the standard groove of ½ inch is obtained.
4. Place a portion of the soil paste in the brass cup of liquid limit device, and by means of spatula, level and smooth the surface of soil.
5. Cut a clean, straight groove in the soil by drawing the grooving tool along the diameter through center of the hinge which separates the soil into two (02) parts.
6. Turn the crank of the liquid limit device at the rate of two revolutions per second and count the number of blows (drops) until two parts of the soil come into contact at the bottom of the groove along a distance ½ inch.
7. Take about 20-40 grams of sample of soil from the closed part of the groove for subsequent water content determination and put it in a pre-weighed moisture content container. Remove the remaining soil from the brass cup and return it to the container. Wash and dry the cup.
8. Repeat steps 4, 5, 6 and 7 atleast four times using the same soil sample to which further small increments of distilled water have been added. The amount of water added must be such that the blows (drops) count range between 10 and 50.
9. The test should always proceed from the drier to the wetter conditions. If it should occur that too much water was added to the soil must never be “dried” by adding additional dry soil. The proper procedure is to thinly spread the wet soil on the glass plate and let it air dry to the desired consistency. Continuous mixing and fanning of the wet soil is permitted to expedite the drying process.
10. Weight the moisture containers and place them in the oven to dry overnight.11. The U.S Army Corps of Engineers found from an investigations conducted with 767
liquid limit determinations that the liquid limit of a soil could be reliably obtained by conducting only one trial and using the following correlation equation;
L .L=wn(N25
)0.121
N = Number of blows required to close the standard groove for distance of ½ inch.Wn = Moisture content of the soil which closed after N blows
33
OBSERVATIONS AND CALCULATIONS
Can No. 1 2 3 4
Wt. of wet soil + can (grams)
Wt. of dry soil + can (grams)
Wt. of can (grams)
Wt. of dry soil (grams)
Wt. of moisture (grams)
Water content (%)
No. of blows
34
PROCEDURE FOR LIQUID LIMIT DETERMINATION
1. Take about 20 grams of air dried soil from the thoroughly mixed portion of the material passing No. 40 sieve. Mix it on the glass plate with sufficient distilled water to make it plastic enough to be shaped into a ball. Leave the plastic soil mass for some time to mature.
2. Take about 8 grams of the plastic soil, make a ball of it, and roll it between the fingers and glass plate with just sufficient pressure to roll the mass into a thread of uniform diameter throughout its length. When the diameter of the thread has decreased to 1/8 inch. The specimen is kneaded together and rolled out again. Continue the process until the thread just crumbles at 1/8 inch diameter.
3. Collect the crumbled soil thread in the container for water content determination.4. Repeat the test for three to four times and take average value of these readings.
OBSERVATIONS AND CALCULATIONS
Can No. 1 2 3 4
Wt. of wet soil + can (grams)
Wt. of dry soil + can (grams)
Wt. of can (grams)
Wt. of dry soil (grams)
Wt. of moisture (grams)
Water content (%)
PRECAUTIONS
Make sure that the liquid limit test should always proceed from the drier to the wetter conditions. Otherwise, drying of soil sample may cause wastage of time.
ReferenceASTM D4318Standard test methods for liquid limit, plastic limit, and plasticity index of soils
35
COMMENTS
36
EXPERIMENT NO. 5(A)
COMPACTION TEST (STANDARD AASHTO)
OBJECTIVE
To perform the standard compaction test and to obtain the moisture density relationship for a given compactive effort on a particular soil.
THEORY
Compaction is a type of mechanical stabilization where the soil mass is densified with the application of mechanical energy also known as compactive effort. The mechanical energy may be produced by dynamic load, static load, vibration, or by tamping. During compaction the soil particles are relocated and the air volume is reduced.
Compaction of soil increases its density and produces three (03) important effects;1. Increase in shear strength of soil2. Decrease in future settlement of the soil3. Decrease in permeability of soil
These three (03) effects carry much importance in the construction of any structure. As a general rule, the greater the compaction, greater these benefits will be. Compaction is actually a rather cheap and effective way to improve the properties of a soil.
The amount of compaction is quantified in terms of the density (dry unit weight) of the soil. As a general rule, dry soil can be best compacted (and thus a greater density achieved) if for each soil a specified amount of water is added to it. In fact the water acts as a lubricant and allows the soil particles to be packed together better. Thus for a given compactive effort, there is a particular moisture content at which the dry density is greatest and the compaction is best. This moisture content is called the “Optimum Moisture Content” and the associated dry density is called “Maximum Dry Density”.
The usual practice in the construction industry is to perform laboratory compaction tests on representative samples from the construction site to determine the Optimum Moisture Content and Maximum Dry Density. Thus Maximum Dry Density is used by the designer in specifying the design shear strength, resistance to future settlement and permeability characteristics. The soil is then compacted by field compaction methods to achieve the laboratory Maximum dry density (or percentage of it). In-place soil density tests are used to determine if the laboratory Maximum Dry Density (or an acceptable percentage) has been achieved.
For determining the moisture-density relationship, following are the two (02) methods;
1. Standard Proctor test (Standard AASHTO)2. Modified Proctor test (Modified AASHTO)
37
APPARATUS
1. Compaction mould with base plate and collar(Mould height = 4.584 inch, Mould internal diameter = 4 inch, Mould volume = 1/30 cft)
2. Standard compaction rammer(5.5 lbs with free fall of 12 inch)
3. Moisture tins4. Large mixing utensil5. Large mixing spoon6. Trimming knife7. Steel straight edge8. Drying oven9. Weighing balance (Least count = 0.01 gram)10. Weighing balance (Least count = 1.0 gram)
PROCEDURE
1. Take a representative quantity (3 kg) of air dried soil that passes the U.S No. 4 sieve. If the material has to be broken up, it should be accomplished in a manner that does not crush the soil particles.
2. Mix the soil sample with a percentage of water by dry weight from and inspection of the soil specimen (about 7 % for sandy soils and about 10 % for clayey soils). Keep this soil in an air tight container for 20 hours for maturation.
3. Weigh the compaction mould lass than the collar and base plate.4. Measure the compaction mould to determine its volume. Attach the collar nad base plate
to the mould.5. Use the standard compaction method and compact the soil in three (03) equal layers,
each layer being given 25 blows from the rammer weighing 5.5 lbs dropping from a height of 12 inches. The blows should be uniformly distributed over the surface of each layer. The amount of soil used should be just sufficient to fill the mould leaving about ¼ inch to be struck off when the collar is removed.
6. Remove the collar and base plate carefully; strike both the top and base of the compacted cylinder of soil with a straight edge. Fill in any holes in the compacted specimen with soil.
7. Clean the mould from outside and weight it to the nearest 1 gram.8. Extrude the cylinder of soil from the mould, split it and take soil sample for moisture
determination.9. Break the sample to No. 4 sieve size and 2 percent (based on the original sample
weight) of water. Carefully remix and repeat step 5 to 9 until, based on wet weights, a peak value is followed by two slightly lesser compacted weights.
10. Return to the laboratory the following day and weigh the oven-dry water content samples to find the actual water content of each test.
11. Plot zero air void line/ saturation curve.
38
PRECAUTIONS
1. On each soil layer, blows should be applied uniformly.2. If the mould is not filled above the collar joint from the last compacted layer, do not add
soil to make up the deficiency. Always redo the test.
OBERVATIONS AND CALCULATIONS
Sample No. 1 2 3 4 5 6
Moisture can No.
Wt. of can + wet soil (g)
Wt. of can + dry soil (g)
Wt. of water (g)
Wt. of can (g)
Wt. of dry soil (g)
Water Content (%)
39
Assumed moisture content (%)
Water content (%)
Wt. of soil + mould (g)
Wt. of mould (g)
Wt. of soil in mould (g)
Wet density, γb (kN/m3)
Dry density, γd (kN/m3)
Standard Proctor Compaction Test
Water Content (%)
Dry
Den
sity
(kN
/m3)
40
REFERENCE
ASTM D698Standard test method for laboratory compaction characteristics of soil using standard effort (12,400 ft-lbf/ft3 (600 kN-m/m3))
COMMENTS
41
Experiment No. 5(b)
COMPACTION TEST (Modified AASHTO)
APPARATUS
1. Compaction mould with base plate and collar(Mould height = 4.584 inch, Mould internal diameter = 4 inch, Mould volume = 1/30 cft)
2. Standard compaction rammer(10 lbs with free fall of 18 inch)
3. Moisture tins4. Large mixing utensil5. Large mixing spoon6. Trimming knife7. Steel straight edge8. Drying oven9. Weighing balance (Least count = 0.01 gram)10. Weighing balance (Least count = 1.0 gram)
PROCEDURE
1. Take a representative quantity (3 kg) of air dried soil that passes the U.S No. 4 sieve. If the material has to be broken up, it should be accomplished in a manner that does not crush the soil particles.
2. Mix the soil sample with a percentage of water by dry weight from and inspection of the soil specimen (about 7 % for sandy soils and about 10 % for clayey soils). Keep this soil in an air tight container for 20 hours for maturation.
3. Weigh the compaction mould lass than the collar and base plate.4. Measure the compaction mould to determine its volume. Attach the collar and base plate
to the mould.5. Use the modified compaction method and compact the soil in five (05) equal layers, each
layer being given 25 blows from the rammer weighing 10 lbs dropping from a height of 18 inches. The blows should be uniformly distributed over the surface of each layer. The amount of soil used should be just sufficient to fill the mould leaving about ¼ inch to be struck off when the collar is removed.
6. Remove the collar and base plate carefully; strike both the top and base of the compacted cylinder of soil with a straight edge. Fill in any holes in the compacted specimen with soil.
7. Clean the mould from outside and weight it to the nearest 1 gram.8. Extrude the cylinder of soil from the mould, split it and take soil sample for moisture
determination.9. Break the sample to No. 4 sieve size and 2 percent (based on the original sample
weight) of water. Carefully remix and repeat step 5 to 9 until, based on wet weights, a peak value is followed by two slightly lesser compacted weights.
10. Return to the laboratory the following day and weigh the oven-dry water content samples to find the actual water content of each test.
11. Plot zero air void line/ saturation curve.
42
PRECAUTIONS
3. On each soil layer, blows should be applied uniformly.4. If the mould is not filled above the collar joint from the last compacted layer, do not add
soil to make up the deficiency. Always redo the test.
OBERVATIONS AND CALCULATIONS
Sample No. 1 2 3 4 5 6
Moisture can No.
Wt. of can + wet soil (g)
Wt. of can + dry soil (g)
Wt. of water (g)
Wt. of can (g)
Wt. of dry soil (g)
Water Content (%)
Assumed moisture content (%)
Water content (%)
Wt. of soil + mould (g)
Wt. of mould (g)
Wt. of soil in mould (g)
Wet density, γb (kN/m3)
Dry density, γd (kN/m3)
43
Modified Proctor Compaction Test
Water Content (%)
Dry
Den
sity
(kN
/m3)
REFERENCE
T 180Moisture density relations of soils using a 4.54-kg [10-lb] rammer and a 457-mm (18-in.) drop
COMMENTS
44
EXPERIMENT NO. 6(A)
DETERMINATION OF IN-PALCE SOIL DENSITY (CORE CUTTER METHOD)
OBJECTIVE
To present to the students two (02) commonly used methods to determine the in-situ density of soil.
THEORY
Once compaction criteria are established for the soil to be sued at a particular site, generally with both moisture and density limitations, some means of verification of the results must be used. On all small projects and all large projects, this verification is achieved by either the sand-cone method or core cutter method. On a few large projects, nuclear devices have been and are being used. The nuclear method is beyond the scope of this manual and will not be considered further.
Basically, both the sand cone and core cutter methods use the same principle. That is, one obtains a known weight of damp (or wet) soil from a small excavation of somewhat irregular shape (a hole) in the ground. if one knows the volume of the hole, the wet density is simply computed as;
γwet=weight of damp soilvolume of hole
and if one obtains the water content (ω) of the excavated material, the dry unit weight of the material is;
γdry=γwet1+ω
The sand cone and core cutter enable us to determine volume of the material excavated and weight of the excavated material is determined by simply weighing the sample on weighing scale.
APPARATUS
1. Cylindrical core cutter of steel(Height = 127.4 mm, Internal diameter = 100 mm, Wall thickness = 3 mm)
2. Steel dolly(Height = 25 mm, Internal diameter = 100 mm, Wall thickness = 7.5 mm)
3. Steel rammer4. Knife5. Steel rule
45
6. Spade or grafting tool7. Weighing balance (Least count = 0.01 gram)8. Weighing balance (Least count = 1.0 gram)9. Moisture tin10. Straight edge
PROCEDURE
1. Measure the inside dimensions of the core cutter and calculate its volume.2. Weigh the core cutter without dolly to the nearest 1 gram.3. Expose the small area, about 30 cm square, to be tested and level it. Put the dolly on the
top of the core cutter and drive the assembly into the soil with the help of a rammer until the top of the dolly remains 1 cm above the surface.
4. Dig out the core cutter from the surrounding soil, and allow some soil to project from the lower end of the cutter. With the help of the straight edge, trim flat the end of the cutter. Take out the dolly and also trim the other end of the cutter.
5. Weigh the cutter full of soil to the nearest 1 gram.6. Keep some representative sample of soil for water content determination.7. Repeat the test at three locations.
PRECAUTIONS
1. While trimming the soil from both ends of core cutter, make sure a leveled and smooth surface is obtained without cavities.
2. Core cutter should be driven in soil vertically; otherwise it would be difficult to extract the core cutter.
46
47
OBSERVATIONS AND CALCULATIONS
Test No. 1 2 3
Wt. of core cutter (g)
Wt. of core cutter + wet soil (g)
Wt. of wet soil (g)
Volume of core cutter (cc)
Bulk density (g/cc)
Container No.
Wt. of container (g)
Wt. of container + wet soil (g)
Wt. of container + Dry soil (g)
Wt. of water (g)
Wt. of dry soil (g)
Water content (%)
Dry density (g/cc)
COMMENTS
48
EXPERIMENT NO. 6(B)
DETERMINATION OF IN-PALCE SOIL DENSITY (SAND REPLACEMENT METHOD)
APPARATUS
1. Density apparatus, consisting of a cylinder with attached cone separated by a shutter and base plate
2. Cylindrical calibrating container3. Glass plate4. Tools for excavating hole5. Weighing balance (Least count = 0.01 gram)6. Weighing balance (Least count = 1.0 gram)7. Clean dry flowing sand (graded between B.S sieves No. 25 and 52)
PROCEDURE
Determining the in-situ density by sand replacement method mainly involves three (03) steps;
A. Determination of weight of sand filling the coneB. Determination of bulk density of sandC. Determination of dry density of soil in place
A. Determination of Weight of Sand Filling the Cone
1. Put sand in the apparatus and record the weight of the apparatus and the sand as W1.2. Place the apparatus on a glass plate which is placed on a clean, level, plane surface (if
base plate is to be used then place the base plate on a glass plate and seat the apparatus in the opening of the base plate)
3. Open the valve and keep it open until the sand stops running out of the jar.4. Close the valve sharply. Remove and weigh the apparatus with its remaining sand and
record the weight as W2.5. Determine the weight of the sand required to fill the cone as W3.
W 3=W 1−W 2
6. Replace the sand removed in the cone determination.
B. Determination of bulk density of sand
1. Determine the volume (V) of the calibrating container by filling it with water full to the brim and finding the weight of water. This volume should be checked by calculating it from the measured internal diameter of the container.
49
2. Weigh the calibrating container and record it as W4. Place the sand cylinder concentrically on the top of the calibrating container. Open the valve and permit the sand to rum into the container. When no further movement of sand is seen, close the valve. Remove the excess sand, level and clean the calibrating container and weigh it along the sand. Let this weigh by W5. Then weight of sand filling the calibrating container W6 is;
W 6=W 5−W 4
The bulk density of soil is;
γbs=W 6
V
C. Determination of Dry Density of Soil In-Place
1. If not already determined, weigh the apparatus with sand in it to the nearest 1.0 gram and record as W7.
2. Prepare the surface of the location to be tested so that it is a level plane.3. Dig the test hole inside the base plate opening; being careful to avoid disturbing the soil
that will bound the hole. Soils that are essentially granular require extreme care. Place all removed soil in the container with a tight-fitting lid or cover to avoid loss of moisture, being careful to avoid losing any material.
4. Seat the apparatus in the base plate opening and open the valve. Close the valve after sand has ceased to run out of the cylinder. (Be careful not to vibrate the apparatus).
5. Weigh the apparatus and its remaining sand and record the weight as W8.6. Weigh the wet soil that was removed from the hole and record it to nearest 1.0 gram as
W9.7. Mix the material taken from the hole thoroughly and select a representative sample for
soil moisture content determination. (Do not over mix, as this will dry the soil). Record the weight of the sample to the nearest 0.01 grams).
8. Dry the wet soil sample and record its dry weight to the nearest 0.01 gram.
50
OBSERVATIONS AND CALCULATIONS
A. Determination of Weight of Sand Filling the Cone
1. Wt. of apparatus + Sand (before test) = W1 = (grams)2. Wt. of apparatus + Sand ( after filling cone) = W2 = (grams)3. Wt. of sand in cone = W3 = (grams)
B. Determination of Bulk Density of Sand
4. Volume of calibrating container = V = (cm3)5. Wt. of calibrating container = W4 = (grams)6. Wt. of calibrating container + Sand = W5 = (grams)7. Wt. of sand (in vol. V) = W6 = (grams)8. Bulk density of soil = γbs = (gm/cm3)
C. Determination of Dry Density of Soil In-Place
9. Wt. of the wet soil from the hole = W = (grams)10. Wt. of apparatus + Sand (before poring in the hole) = W7 = (grams)11. Wt. of apparatus + Sand (after pouring in the hole) = W8 = (grams)12. Wt. of sand in the hole = W9 = (grams)13. Bulk density of soil = γb = (gm/cm3)
COMMENTS
51
APPENDIX
(RELEVANT ASTM STANDARDS)
52
