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288 rETHOOS OF SAMPLING AND TESTINGStandard Method of Test or

: Determining he Liquid Limit of SoilsAASHTO DESIGNATION: T 89-81

l. DEFlNmON1.1 The Liquid Limit of a soil is that water content, as determined in accordance with thefollowing procedure, at which the soil passes rom a plastic to a liquid state.

2. APPARATUS2.1 Dish-A porcelain dish, preferably unglazed, or similar mixing dish, about 115 mm(4V2 in.) in diameter.2.2 Spatula-A spatula or pill knife having a blade about 75 mm (3 in.) in length and about20 mm (3 . in.) in width.2.3 Liquid Limit Device:2.3.1 Manually Operated-A device consisting of a brass dish and carriage, constructedaccording to the plan and dimensions shown in Fig. l.2.3.2 Mechanically Operated -A motorized device equipped to produce the rise and rate ofshoclcs o a brass cup as described in sections 4.2 and 5.3 of this procedure, respectively. The cupand the critica dimensions of the device shall conform to those shown in Fig. 1 of this procedure.The device shall give the same iquid limit values as obtained with the manually operated device.2.4 Grooving Tool-A grooving tool conforming to the critica dimensions shown in Fig. l.The gage need not be part of the tool.2.5 Gage-A gage, whether attached to the grooving tool or separate, conforming to the

critical dimension "e" shown in Fig. 1 and may be, if separate, a metal bar 10.00 :t 0.02 mm(0.394 :t 0.001 in.) thick and approximately 50 mm (2 in.) long.2.6 Containers-Suitable containers, such as metal caos with lids, which will prevent lossof moisture prior to and during weighing.2.7 Balance-A balance sensitive o 0.01 g.2.8 Oven-A thermostatica1ly controlled drying oyen capable of maintaining temperaturesof 110 :t 5 C (230 :t 9 F) for drying moisture samples.

METHOD A3. SAMPLE

3.1 A sample weighing about 100 g shaIl be taken from the thoroughly mixed portion of thematerial passing the 0.425 mm (No. 40) sieve which has been obtained in accordance withAASHTO T 87, Standard Method of Preparing Disturbed Soil Samples, or T 146,Standard Meth-od of Wet Preparation of Disturbed Soil Samples for Test; for structural analysis use AASHTO T146, Method B.4. ADJUSTMENT OF UQUID LIMIT DEVICE

4.1 The Liquid Limit Device shaIl be nspected to determine that the device is in good work-ing order; that the pin connecting the cup is not worn sufficiently to permit side play; that thescrewsconnecting the cup to the hanger arm are tight; the points of contact on the cup and baseare not excessivelyworn; that the lip of the cup is not excessivelyworn; and that a groove has not-88r.1

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T89 METHOOS OF SAMPLING ANO TESTING 289cprfCNAL

END ftOJND [M)~&~;~;;~SQUARE25.41"1" ,lo.-"d~ .OOdIO17/8"O ,b .r-CL I ~~==:=:J1::J .. . -. .= 8)0 ..l. t tGROC1l/ING OOL

I M ..SS

N

F ,K HARDRUBBERTAE LE OF MEASUREMENTS

LlOUID LlMIT OEVICE GROOVING TOOLCUP ASSEMBLY BASE CURVED EN~ GAGE

DIMENSION A B C N K L M a b c d eS THICK- DEPT ;~ ~'ADiU NESS H CAM THICK- THICK. UTTWGDESCRIPTION OF OF OF FOlWN. NE$ LENGTH WIOTH NESS EDGE WIOTH D~ WlCT"OS' CUP CUP .~W

METRIC,mm. 54 2.0 27 47 50 150 125 10.0 2.0 15.5 10D 10.(TOLERANCE, mm. 2 0.1 1 1.5 5 5 5 0.1 0.1 0.1 0.2ENGLISH, in. 2.15.079 1.063 I.B50 1.97 5.~ 4.92 .~9~ s:' ' .551 .5957 .39~7TOLERANCE, in DB.OO4.04 .06 .2 .2 .2 .004 .004 .004 .001

NOTE ~ote "H" moy be de~..d for usinQ I seorinQ oc- (1)An additionol welY taleronce of +O,lmm .hall be ollowed for dimensKln"b" for us8d 91OOvlrIQ toolsFeet far base stdl be of ~ilient materialThe metric unit" nre the required dimensian The En91ish Units are appraxi~te cx.nversian..

Fi~re I Mnl1'Jal Liquid Limit Device

been wom in the cup through long usage. The grooving tool sha 1 be inspected to determine thatthe critica dimensions are as shown in Fig. l.NOTE 1: Wear is considered excessivewhen the point of contact on thc cup or base exceedsapproximatc(y 13 mm (0.5 in.)in diameter, or when any pointon the rim of the cup is worn to approximately ~ the original thickness. Although a slight groovein the center of the cup is noticeable, it is not objectionablc. lf the groove becomespronounced bcfore other signo of wear appear,the cup should bc considered excessivelyworn. Excessivelyworn cupo shall bc replaced. A base which is excessively worn mar bcrefinished as long as the thickness does not exceed the tolerance shown in Fig. 1 by more than -2.5 mm (-0.1 in.) and thedistance between he cup at the cam follower and the base s maintained within the toleranc.. specified in Fig. l.

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,.

290 METHODSOF SAMPLlNG AND TESTING T89 I4.2 By mecmsof the gage, and the adjustment plate H, Fig. 1, the height to which the cup C

is lifted shall be adjusted so that the point on the cup which comes in contact with the base is10 mm (0.394 in.) above base. The adjustment plate H shall then be secured by tightening the rcrew(s) . With the gage still in place, the adjustment shall be checked by revolving the crankral?idly several imes. If the adjustm~nt i~ correct a slight ringing sound. will be heard when.the camstnkes the cam follower. If the cup IS raIsed off the gage or no sound IS heard, further adjustmentshall be made.S. PROCEDURE l.

5.1 The soil sample shall be placed in the mixing dish and thoroughly mixed with 15 to 20 mi \of distilled of demineralized water by altemately and repeatedly stirring, kneading and choppingwith a spatula. Further additions of water shall be made in increments of 1 to 3 mi. Each incrementof water shall be thoroughly mixed with the soil as previously described before another incrementof water is added. Once testing has begun, no additional dry soil should be added to the moistenedsoiloThe cup of the Liquid Limit Device shall not be used for mixing soil and water oNOTE 2-Some soils are slow to absorb water, Iherefore, it is possible to add the increments of water so fast

that a false liquid limit value is obtained. This can be avoided if more mixing andjor time is allowed. Tap watermay be used for routine testing if comparative tests indicate no differences in results between using tap water anddistilled or demineralized water. However, referee or disputed tests shall be performed using distilled or deminera-lized water.5.2 When sufficient water has been thoroughly mixed with the soil to form a uniform massof stiff consistency, a sufficient quantity of this mixture shall be placed in the cup above the spotwhere the cup Testson the base and shall be squeezedand spread with the spatula to level and atthe same time trimmed to a depth of 10 mm at the point of maximum thickness. As few strokes ofthe spatula as possible shall be used, CaTe ei~g taken to prevent the entrapment of air bubbleswithin the mass. With the spatula the soil shall be leveled and at the same ime trimmed to a depthof 10 mm at the point of maximum thickness. The excesssoil shall be retumed to the mixing dish.

The soil in the cup of the device shall be divided by a firm stroke of the grooving tool along thediameter through the centerline of the cam follower so that a clean sharp groove of the proper rdimensions will be formed as shown in Fig. 2. To avoid tearing of the sides of the groove or slip- lping of the soil cake.on the cup, up to six strokes from front to back or from back to front count-ing as one stroke, shall be permitted. The depth of the groove should be ncreased with each strokeand only the last stroke should scrape he bottom of the cupo5.3 The cup containing the sample prepared as described in 5.2 shall be lifted and droppedby tuming the crank F at the rate of approximately two revolutions per second until the two sidesof the sample come in contact at the bottom of the groove along a distance of about 13 mm (0.5 in.).The number of shocks required to clase the groove this distance shall be recordedoThe base of themachine shall not be held with the free hand while the crank F is tumed.NOTE 3: Some soils tend to olido on the surface of the cup instead of fiowing. If this occurs, more water should be added tothe sample and remixed, then the soil-water mixture placed in the cup, a groove cut with the grooving tool and 5.2 repeated. If i-the soil continues to slide on the cup at a lesser number of blows than 25, the test is not applicable and a note should be made that .-Ithe liquid limit could not bedetermined. "5.4 A slice of soil approximately the width of the spatula, extending from edge to edge of he soil cake at right angles to the groove and including that portion of the groove in which thesoil flowed toget.her, shall be removed and .placed n a suitable c.o~tainer. The .container and soilshall then be welghed promptly and the welght recorded. The soll In the contaIner shall be oven-dried to a constant weight at 110 :t 5 C (230 :t 9 F) and weighed. This weight shall be recorded and rthe 1055n weight due to drying shall be recorded as the weight of water. .5.5 The soil remaining in the cup shall be transferred to the mixing dish. The cup and groov- \,'ing tool shall then bewashed and dried in preparation for the next trial. ;5.6 The foregoing operations shall be repeated for at least two additional portions of the \sample to which sufficient water has been added to bring the soil to a more fluid condition. Theobject of this procedure is to obtain samples of such consistency that at least one determinationwill be made in each of the following ranges of shocks: 25-35, 20-30, 15-25, so the range in thethree determinations is at least 10 shocks. Cr'

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.T89 METHOOS OF SAMPLING ANO TESTING 2916. CALCULA TION

6.1 The water content of the soil shal1 be expressedas the moisture content in percentage ofthe weight of the oven-dried soil and shall be calculated as fol1ows:mass of waterPercentagemoisture = x 100mass of oyen dried soil

~Cc

"{?Fig. 2. Liquid limit device witb soil sample in place.

7. PREPARATION OF FLOW CURVE7.1 A "Flow Curve" representing the relation between moisture content and correspondingnumber of shocks shall be plQtted n a semi-logarithmic graph with the moisture contents as abscissaeon the arithmeticai scale,and the number of shocks as ordinates on the logarithmic scale. The flow

curve shall be a straight line drawn as nearly as possible through the three or more plotted points.8. LIQUID LIMIT8.1 The moisture content corresponding to the intersection of the flow curve with the 2Sshock ordinate shall be taken as the liquid limit of the soil. Report this value to the nearest wholenumber.

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T89 METHODS OF SAMPLING AND TESTING 293WATER CONTENT ATN BLOW5 (w")150 -:'LIQUID LIMIT14f (LL) -W . L 0.111rl50 LL- N (25)130 -+-140

120 13010 I~O .100 110, 100 NUMBER OF90 BLO~S (N)9080 4080

70 3570 .60 60 30~O 50 25

KE'fW40 40 NLL 20

.30 30 t-fI~

ENTER CHART WITH w" AND NiSTRA IGHT ED.GE DETERMINES L L2020

Fil. J. Nomographic Chart Developed by the Watenvays Experiment Station, Corps of Engjneers,U. S. Army, to Determine Liquid Limit Usinl Mean Slope Method.

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294 METHODS OF SAMPLING AND TESTING T89

S6 , I, ,

SO. ,". ,: .., , \25 I .' ,o 11\ .\ , "o , ' \ 1 l' 1\ " ,\

I '1 I I \20 .1, o ,VI ' , I 1 \ 11 "~ lo 1 '\i 11 ; :', '\ ; ,3 17 I \ \ t" 1 ~ \ \ , 1;~ ~ ~11) 10 15 20 25 SO 35 40 4S 50 55 60t..Oa: 36UJ11)~J t o 'Z" I, ,, , '2' ;' '", ' ;"" ,, '\ ,, '\;20 1 : I I ;'" 11. 1\l' ~ ,~ \ \ \\\ \ \'~ '\1 \1 \1 \1 ' ,"'1755 60 65 70 75 80 85 90 95 100 105MOI STURE CONTENT -PERC ENT

Fig. 4. Chart Developed by Washington SiRte Highway Departmentlor the Calculation 01 the Liquid Limit.

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T89 METHOOS OF SAMPLING ANO TESTING 295

I : 1""""1"""i"'192A- LOCATIONOF SPECIAL SCALE (BLOWS) WITH RESPECTTO B SCALEOF SUDE RULE

B -SUDE RULE SET FOR 21.4 PERCENTMOISTURE AT 20 BLOWS INDICATI NGCALCULATEDUOUID UMIT OF 20.8FIG. S. Slide Rule with SpecialScale for the Calculation of the Liquid Limit.

CHECK OR REFEREE TESTS13. METHOD TO BE usm13.1 In making check or referee tests, Method A shall be used. The results of liquid limit testsare influenced by:13.1.1 The time required to make the test.13.1.2 The moisture content at which the test is begun.13.1.3 The addition of dry soil to the seasoned ample.

14. PROCmURE14.1 Therefore, in making the liquid limit test for check or referee purposes, the followingtime schedule shall be used;14.1.1 Mixing of soil with water-5 to 10 minutes, the longer period being used for the moreplastic soils.14.1.2 Seasoning n the humidifier-30 minutes.14.1.3 Remixing before placing in the brass cup-add I mi of water and mix for I minute.14.1.4 Placing in the brass cup and testing-3 minutes.14.1.5 Adding water and remixin;-3 minutes.14.2 No trial requiring more than 35 blows or less than 15 blows shall be recorded. In nocase shall dried soil be added to the seasonedsoil being tested.

15. PRECISION STATEMENT15.1 Repeatabi/ity-(single operator)- Two results obtained by the same operator on the samesample in the same laboratory using the same apparatus, and on different days should be consideredsuspect f they differ by more than 7 percent of their meaR.15.2 Reproducibi/ity-(multi-laboratory)- Two results obtained by different operators in dif-ferent laboratories ifthey differ by more than 13 percent oftheir mean.