LAB EXPERIMENT #2 & 3: SIEVE & HYDROMETER ANALYSIS FOR SOIL GRAIN SIZE DISTRIBUTION

Sieve Data:SieveNumberSieveOpeningSize (mm)Mass ofSieve (g)MassRetained(Sieve +Soil)(g)Mass Retained(Sieve + Soil)(g)Group 1 ,2 Groups 3, 4, 54 4.760 499.60 509.60 514.68 2.360 475.90 491.00 485.910 2.000 481.50 495.00 49416 1.180 435.40 515.80 509.920 0.850 405.80 454.80 460.840 0.425 386.40 502.50 486.850 0.300 370.60 436.31 405.260 0.250 372.40 396.70 390.8100 0.150 349.30 399.18 414.3200 0.075 304.20 324.15 338.4PAN 183.46 238.33 263.86TOTALLab #3- Hydrometer Analysis Data SheetDescription of soil: _ Look at table belowTemperature.: _______20 degree Celsius___model 152H__Location: ____Soils lab_____________Date: ______09/22/2020____________________Time(t, min.)Hydrometer Reading(R)Group #1 Group #2,4 Group #3, 5BrownSandy clayClayey Silt Silt0.25 51 51 No reading0.5 50 50 481 49 49 472 48 47 424 47 45 378 46 44 3315 45 43 3030 44 41 2660 43 39 23120 41 37 No reading240 39 34 No reading480 37 31 181440 35 27 No reading2880 No reading 24 No readingGRAIN SIZE ANALYSIS OF SOILSDEFINITIONGrain size analysis is the determination of the size grainof particles present in a soil. It is expressed as apercentage of the total dry weight. Two tests aregenerally used to find particle size distribution of soil:(1) Sieve analysis. (2) Hydrometer analysis.INTRODUCTION• The sieve analysis is generally applied to the soil fraction largerthan 75 µm (retaining on the No. 200 Sieve). Grains smaller than75 µm (0.075 mm) are sorted by using sedimentation process(hydrometer analysis).The basic principles for sieve analysis andhydrometer analysis are described in the following twosections.SECTION ONESIEVE ANALYSISDEFINITIONSieve analysis consists of shaking the soil sample through a set ofsieves that have progressively smaller openings.INTRODUCTION• Fortunately, not all soils contain the full range of particle sizes so the testcan be simplified. Soils that are non-cohesive may only require dry sieving.It is usually considered that the sedimentation procedure is not necessaryif the soil contains less than 10% fines.• Soils may be divided on the basis of their dominating particle size sixarbitrary categories which are called boulders, cobbles, gravel, sand, siltandclay.Sieve Designation0.002 0.06 2 60mmcolloids fine medium coarseCLAY SILT SAND GEAVEL COBBLESParticle Size 1 5 75 425µm 2.00 4.75 75 mmNo.200 No.40 No.10 No.4(a) U.S.A. ASTM: American Society for Testing and Material D422Particle Size 2 6 20 60 200 600µm 2 6 20 60 200 mm(b)BS 1377:1975 British StandardPARTICLE SIZE DISTRIBUTION CURVE• The particle size distribution curve, also known as a gradationcurve, represents the distribution of particles of different sizes inthe soil mass.A coarse soil is described as:

Well graded if there is no absence of particles in any size rangeand if no intermediate sizes are lacking. The smooth concaveupward grading curve is typical of well-graded soil, which isshown by curve (1) in Fig (a).Poorly graded if:a. A high proportion of the particles have sizes with narrow limits (auniform soil or narrowly graded soil) as shown by curve (2).b. Particles of both large and small sizes are present but withrelatively low proportion of the particles of intermediate sizes(a gap-graded or step- graded soil) as shown by curve (3).• Soil particles have sizes ranging from greater than 200 mm downto less than 0.002 mm (2 µm).CLAY SILT SAND GEAVEL COBBLES BOULDERSfine medium coarse fine medium coarse fine medium coarseFigure (a)PURPOSESTo determine the grain size distribution curve of a soil sample bywhich soil can be classified and their engineering properties assessed.APPARATUSThe equipment used in sieve analysis includes:A series of standard sieves of square mesh, including cover plate andbottom pan. Two recommended sieve stacks (having successively smallermesh sizes) are as shown in table (1):Table (1)Typical Sieve Stack Alternative Sieve StackSieve No. Opening, mm Sieve No. Opening, mmLid Lid4 4.75 4 4.7510 2 10 220 0.85 30 0.640 0.425 50 0.360 0.25 100 0.15140 0.106 200 0.075200 0.075 PanPanSieve shaker.Balance sensitive to 0.1g.Mortar and pestle (or pulverizer for breaking up aggregations of soilparticles).Curve 1Curve 3Curve 2percentfiner(%)Brush (for cleaning sieve).Oven.PREPARATION OF SOIL SAMPLEThe aggregations or lumps of soil tested are thoroughly broken upwith the mortar and pestle or (pulverizer).The specimen to be testedshould be large enough to be representative of the soil in the field. Itshould also be small enough not to overload sieves. The size ofrepresentative specimen depends on the maximum particle size. Table(2) gives some guidelines for selecting the maximum sample weight.Table (2)Maximum Particle Size Minimum Weight of Sample (g)7.5 cm 60005 cm 40002.5 cm 20001 cm 1000Finer than No. 4 sieve 200Finer than No. 10 sieve 100PROCEDUREOven dry the sample, allow it to cool. Then take 500 g (depending onmaximum particle size) of oven dried soil.Select a stack of sieves suitable to the soil being tested. Weigh each sieveand a pan to be used Wo (make sure each sieve is clean before weighing it,by using a brush to remove grains stuck in mesh openings).Arrange the stack of sieves so that the largest mesh opening is at the topand the smallest is at the bottom and attach the pan at the bottom of thesieve stack.Pour the dry sample on the top sieves. Add a cover plate (to avoid dust andlost particles while shaking).Place the stack of sieves in the mechanical shaker and shake for 10 min.Remove the stack of sieves from the shaker, and measure the weight ofeach sieve and the pan with the soil retained on them Wf.Subtract the weights obtained in step (2) from those of step (6) to give theweight of soil retained on each sieve. Their sum is compared to the initialsample weight; both weights should be within about 1%. If the difference isgreater than 1%, too much material was lost, and weighing and/or sievingshould be repeated /Wf – Wo/ > 1%.CALCULATION§ % Retained on each sieve = Weight of soil retained *100

§ % Finer (passing) than any sieve size = 100 – Cumulative of %Retained§ The gain-size distribution curve can be used to determine some of the basicsoil parameters such as the:

Effective size (D10); is the diameter in the particle size distribution curvecorresponding to 10% finer.Uniformity coefficient (Cu); is a measure of the slope of the curve. It is

defined as Cu

D60D10Where D 60 = diameter corresponding to 60% finer.(D )2

Coefficient of gradation or concavity (Cc); is defined as Cc = 30D60 * D10Where D 30 = diameter through which 30% of the total soil mass ispassing.§ Find gravel, sand and (silt and clay) percentage according o ASTM.§ Find coarse, medium and fine sand according to ASTM.DISCUSSIONIn addition of the general questions (from Report Writing) answer the followingquestionsWhich type of curve (Soil) is better to be used in filter design?When we use sieves with wide range opening?Under what conditions should you use wet sieving instead of dry sievin1SIEVE ANALYSIS DATA SHEETName: …………………………………..Class: …………………Group No.: …………………Total sample mass =…………………(1)ASTMSievenumber(2)Sieveopening(mm)(3)Weightof sieve(g)(4)Weight ofsieve + soilretained (g)(5)Weight ofsoil retained(g)(6)%Retainedon eachsieve (g)(7)Cumulativeof%Retained(8)%Passing(finer)4 4.75010 2.00020 0.85030 0.60040 0.425100 0.150200 0.075Pan

Signature: ………………..2B. HYDROMETERIntroductionHydrometer analysis is a widely used method of obtaining an estimate of the distribution of soil particle sizes fromthe No. 200 (0.075 mm) sieve to around 0.01 mm. The data are presented on a semilog plot of percent finer vs.particle diameters and may be combined with the data from a sieve analysis of the material retained (+) on theNo.200 sieve. The principal value of the hydrometer analysis appears to be to obtain the clay fraction (generallyaccepted as the percent finer than 0.002 mm). The hydrometer analysis may also have value in identifying particlesizes < 0.02 mm in frost susceptibility checks for pavement subgrades. This test is done when more than 20% passthrough No.200 sieve and 90% or more passes the No. 4 (4.75 mm) sieve.The hydrometer analysis is based on Stokes’ Law, which gives the relationship among the velocity of fall of spheresin a fluid, the diameter of the sphere, the specific weights of the sphere and of the fluid, and the fluid viscosity. Inequation form this relationship is2 (Gs – Gf )v = —- * ———— * (D / 2)29 hwhere,v = velocity of fall of the spheres (cm/s)Gs = specific gravity of the sphereGf = specific gravity of fluid (varies with temperature)h = absolute, or dynamic, viscosity of the fluid (g /(cm * s))D = diameter of the sphere (cm)Solving the equation for D and using the specific gravity of water Gw, we obtain

D = Ö 18 h v / ( Gs – Gw)

v = L / t

A = Ö 18 h / ( Gs – Gw)

D = AÖ L (cm) / t (min)where 0.002 mm < D < 0.2 mmEquipment

Hydrometer (152H model preferable)Quantity (about 2.5L per test) of distilled waterSedimentation cylinder (1000mL cylinder) also termed a hydrometer jarGraduated 1000 mL cylinder for control jarSoil-dispersion device (malt mixer or air-jet dispersion)Dispersion agent (NaPO3 or Na2 SiO3)3Hydrometer jar bath (optional, for temperature control)ThermometerCorrections to hydrometer readings• Zero Correction (Fz): If the zero reading in the hydrometer (in the control cylinder) is below the watermeniscus, it is (+), if above it is (–), if at the meniscus it is zero.• Meniscus Correction (Fm): Difference between upper level of meniscus and water level of control cylinder.• Temperature correction (Ft): The temperature of the test should be 20°C but the actual temperature may vary.The temperature correction is approximated asFt = -4.85 + 0.25 T (for T between 15°C to 28°C)ProcedurePrepare the control jar by adding 125 ml of 4% sodium metaphosphate (NaPO3) solution and sufficient distilledwater to produce 1000 ml. (This solution can be made by mixing 40g of dry chemical with enough water tomake 1000 ml). Put the hydrometer into the control cylinder and record zero and meniscus correction; thenrecord the temperature by putting the thermometer in itWeigh out exactly 50g of soil passing the No. 200 sieve. Mix the soil with 125 ml of 4% sodiummetaphosphate (NaPO3) solution. Allow the soil mixture to stand about 12 hours.At the end of the soaking period, transfer the mixture to a dispersion (or malt mixer) cup and add tap water untilthe cup is about two-thirds full. Mix for 1 minute. After mixing, carefully transfer all the contents of thedispersion cup to the sedimentation cylinder. Rinse any soil in the dispersion cup by using a plastic squeezebottle or adding stabilized water and pour this into the sedimentation cylinder. Now add distilled water to fillthe cylinder to the 1000 ml mark.Cap the sedimentation cylinder with a No. 12 rubber stopper and carefully agitate for about 1 min. Agitation isdefined as turning the cylinder upside down and back 60 turns for a period of 1 min. An upside down and backmovement is 2 turns.Put the sedimentation cylinder beside the control cylinder and start the stopwatch immediately. This iscumulative time t = 0. Insert the hydrometer into the sedimentation cylinder.Take hydrometer readings at cumulative times t = 0.25 min., 0.5min., 1 min. and 2 min. Always read the upperlevel of meniscus. Remove and place the hydrometer in the control jar.Continue taking hydrometer and temperature readings at approximate elapsed times of 8, 15, 30 and 60 min.and then 2, 4, 8, 24 and 48 hr. For each reading, insert the hydrometer into the sedimentation cylinder about 30sec before reading is due. After the reading is taken, remove the hydrometer and put it back into the controlcylinder.Calculation4Calculate corrected hydrometer reading for percent finer, RCP = R + Ft + FzCalculate percent finer = (A * RCP * 100) / Wswhere,Ws = dry weight of soil used for hydrometer analysisA = correction for specific gravity (as hydrometer is calibrated for Gs = 2.65 )therefore,A = 1.65 * Gs / ((Gs – 1 ) * 2.65 )Calculate corrected hydrometer reading for determination of effective length, RCL = R + FmDetermine L (effective length) corresponding to RCL given in Table 1.Determine A from Table 2

Determine D (mm) = A Ö L (cm.) / t (min.)Table 1. Variation of L with Hydrometer ReadingHydrometerReadingL(cm)HydrometerReadingL(cm)HydrometerReadingL(cm)HydrometerReadingL(cm)012345678910111216.316.116.015.815.615.515.315.21514.814.714.514.31314151617181920212223242514.21413.813.713.513.613.21312.912.712.512.412.2262728293031323334353637381211.911.711.511.411.211.110.910.710.610.410.210.1394041424344454647484950519.99.79.69.49.29.18.98.88.68.48.38.17.9Table-2 Variation of A with GsTemperature (°C)Gs 17 18 19 20 21 22 232.52.552.62.652.72.752.80.01490.01460.01440.01420.01400.01380.01360.01470.01440.01420.01400.01380.01360.01340.01450.01430.01400.01380.01360.01360.01340.01430.01410.01390.01370.01340.01330.01310.01410.01390.01370.01350.01330.01310.01290.01400.01370.01350.01330.01310.01290.01280.01380.01360.01340.01320.01300.01280.0126Temperature (°C)Gs 24 25 26 27 28 29 302.52.552.62.650.01370.01340.01320.01300.01350.01330.01310.01290.01330.01310.01290.01270.01320.01300.01280.01260.01300.01280.01260.01240.01290.01270.01250.01230.01280.01260.01240.012252.72.752.80.01280.01260.01250.01270.01250.01230.01250.01240.01220.01240.01220.01200.01230.01210.01190.01210.01200.01180.01200.01180.0117Combined AnalysisCalculate the percent passing the No. 200 sieve. (This should be equal to the percent finer for the soil retainedon No. 200 sieve from the Sieve Analysis)The modified percent finer = percent finer for hydrometer method x percent passing No. 200 sieve from Step 1.The total modified percent finer for samples retained on No. 200 sieve and above would be the same ascalculated in sieve analysis; for samples passing No. 200 sieve, the same as calculated in Step 2.Note: Plot the percent finer versus grain size for both Hydrometer Method and Combined Method. Use arithmeticscale and vertical axis for percent finer and log scale and horizontal axis for grain size. This curve is called grainsize distribution curve. Comment on results.6DATA SHEET: Hydrometer AnalysisDescription of soil: ____________________Sample No.: ___________________________Location: ___________________________Tested by: ___________________________Group No.: ___________________________Date: __________________________________Time(t, min.)HydrometerReading(R)RCP Percent finerARCP100 /50RCL L(cm)A D(mm)0.250.5124815306012024048014402880

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LAB EXPERIMENT #2 & 3: SIEVE & HYDROMETER ANALYSIS FOR SOIL GRAIN SIZE DISTRIBUTION

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