Wi- 03 Plastic Limit

LABORATORY QUALITY INSTRUCTION

STANDARD TEST FOR DETERMINATION OF PLASTIC LIMIT

Prepared by Approved by

MAIMUNAH ZAINAL ABIDIN KAMARUDIN ZAKARIA

TECHNICAL MANAGER DIRECTOR

Date: 20.10.2015 Date: 20.10.2015

IKRAM SELATAN LABORATORYKUMPULAN IKRAM SDN BHD

LABORATORY WORK INSTRUCTION

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DETERMINATION OF PLASTIC LIMIT

EFFECTIVE DATE : 20.10. 2015

KISB/IS/ISL/LWI-03 PAGE NO : of 18

Table of Contents1. OBJECTIVE.....................................................................................................................................3

2. SCOPE............................................................................................................................................3

3. TERMINOLOGY & ABBREVIATION.................................................................................................3

4. RESPONSIBILITY.............................................................................................................................4

5. APPARATUS...................................................................................................................................4

6. SAMPLE PREPARATION.................................................................................................................4

7. TEST INSTRUCTION........................................................................................................................5

8. CALCULATION................................................................................................................................6

9. GENERAL.......................................................................................................................................7

10. MEASUREMENT UNCERTAINTY.................................................................................................7

10.1. Model equation.....................................................................................................................7

10.2. The components....................................................................................................................7

10.3. Calculation for individual components..................................................................................8

10.3.1. ∆ moisture content, uc wL...................................................................................................8

10.3.2. ∆ standard error of regression, usteyx..................................................................................8

10.3.3. ∆ repeatability, urepeatability.............................................................................................8

10.3.4. ∆ reproducibility, ureproducibility......................................................................................8

10.3.5. ∆ interlab comparison, uPT ..................................................................................................8

10.4. Combined Standard Uncertainty, uc wL..............................................................................9

10.5. Expand the combined standard uncertainty to 95%.............................................................9

10.6. Uncertainty for Moisture content w.....................................................................................9

10.7. Combined standard uncertainty, uCW ..............................................................................10

10.9. The components for moisture content...............................................................................10



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10.10. Calculation for ur................................................................................................................10

10.11. Calculation for us................................................................................................................13

10.12. Calculation for usteyx.........................................................................................................14

11. ATTACHMENT..........................................................................................................................15

1. OBJECTIVETo outline the instructions to be followed for the determination of the plastic limit of soil samples base on BS 1377 : Part 2 : 1990 : clause 5.3, MS 1056:2005, clause 6.3.

2. SCOPEThese instructions are applicable to all ISL personnel involved in the determination of the plastic limit for soil samples. The plastic limit is the empirically established moisture content at which a soil becomes too dry to be plastic. It is used together with the liquid limit to determine the plasticity index which when plotted against the liquid limit on the plasticity chart provides a means of classifying cohesive soils.

3. TERMINOLOGY & ABBREVIATION3.1. Abbreviation

3.1.1. Technical3.1.1.1. CDDL :Controlled Document Distribution

List3.1.1.2. GL :Ikram Selatan Laboratory3.1.1.3. Position3.1.1.4. QM :Quality Manager3.1.1.5. TM :Technical Manager3.1.1.6. LE :Laboratory Executive3.1.1.7. LO :Laboratory Officer



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4. RESPONSIBILITY4.1. The TM is responsible for supervising and coordinating

the tests done by all laboratory personnel.4.2. The TM is responsible for supervising and coordinating

the tests done by all laboratory personnel.4.3. The LE is responsible for conducting soil tests in

accordance to the standard.4.4. The LO shall assist the LE in preparing the test items

for the test.

5. APPARATUS5.1. Flat glass plate, convenient size is 10mm thick and

about 500mm2.5.2. Test sieve size 425μm5.3. Wash bottle or beaker.5.4. stopwatch readable to 1s.5.5. Drying oven capable of maintaining temperature from

105°C to 110°C5.6. Electronic weighing balance readable to 0.01g5.7. Desiccator containing anhydrous silica gel5.8. Small items

5.8.1. sample tray5.8.2. scoop5.8.3. soil container5.8.4. spatula5.8.5. knife

6. SAMPLE PREPARATION6.1. sample preparation

6.1.1. Soil samples are dried and broken down mechanically as described in WI-General B- Drying and Pounding Process.



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6.1.2. When possible, the soil sample shall be treated in its natural state, particularly with clay soils. Coarse materials shall be removed by picking them out by hand or spatulas.

6.1.3. Take a sample of about 300g from the soil paste prepared as specified (natural condition or passing the 425µm BS sieve) and place it on the glass plate.

6.1.4. Slowly add distilled water to the sample, mix well with two palette knives until it becomes homogeneous paste.

6.2. equipment preparation6.2.1. set the oven temperature between 100 to 115 ºC

and allow to stabilise.

7. TEST INSTRUCTION7.1. Take about 20g of pre-prepared sample and put it on the

glass plate.7.2. Thoroughly mix the soil with distilled water into a

homogeneous paste using the two palette knives. Allow the soil to dry partially on the plate until it becomes plastic enough to be shaped into a ball.

7.3. Mould the ball of sample between the fingers and roll it between the palms until the heat of the hands has dried the sample sufficiently for slight cracks to appear in its surface. Roll the sample on the glass plate with the palm. Divide this sample into two sub-samples of about 10g each and carry out separate determination on each portion. Divide each sub-sample into four, more or less equal parts

7.4. Mould the soil in the fingers to equalize the distribution of moisture. Form the soil into thick threads by rolling the soil between the palms and then roll the threads between the fingers (from finger-tip to second joint) of one hand and the surface of the glass rolling plate. Alternate between moulding and rolling to effect the gradual drying of the soil.



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7.5. Roll the sample into threads between the fingers, from the finger-tip to the second joint of one hand and the palm of the other hand until the thread shears both longitudinally and transversely when it has been rolled to about 3 mm in diameter size. Do not gather the pieces of sample together after they have crumbled, in order to reform a thread and to continue rolling; the first crumbling point is the plastic limit.

7.6. Take 2 metal containers and record their identification on the form F-WI-06A. Weigh each container separately and record their weights.

7.7. Place the crumbled thread into one container and repeat process 7.4 to 7.6 on the three other remaining portions, placing them all in the same container. Weigh the container containing the crumbled threads and record the weight.

7.8. Repeat the process of the duplicated sample the crumbled threads into another container. Weigh the container and contents, and record the weight.

7.9. Place the two containers in the oven at a temperature of 105ºC -110ºC for18 hours. After drying, remove the containers from the oven and allow them to cool in a desiccator. Record the dry weight and determine the moisture content as specified in the moisture content test WI-06A-01.

7.10. Record the two moisture content values of the soil sample in form F-WI-06.

8. CALCULATION8.1. Average moisture content for each test according to WI-

01 Moisture Content.8.1.1. The moisture content of the soil (w) is

calculated as a percentage of the dry soil mass.8.1.2. The equation is :-

w=m2−¿m3

m3−m1x100 %¿

Where m1 is the mass of container (in g)



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m2 is the mass of container and wet soil sample (in g)m3 is the mass of container and dry soil sample (in g)w is the moisture content (in %)

8.1.3. The value of w for moisture content determination is calculated to the nearest 0.01%.

8.2. Acceptance criteria8.2.1. If the two results differ by more than 0.5 %

moisture content, repeat the whole test.8.3. Calculate the average moisture content for the two test

when the above criteria meet.8.3.1. Let the moisture content of each trial be w1 ,w2 , 8.3.2. Average moisture content, w

w=w1+w2

2

8.3.3. This value is reported as plastic limit of the soil specimen tested.

9. GENERAL

9.1. All raw data and a visual description or general classification of the soil based on what is seen, felt and smell are recorded in the Test Form KISB/WI-06.

9.2. The LE shall compile, check and enter the raw data into the computer for results and report writing

9.3. For details, please refer to BS 1377:1990 Part 2 clause 5.

10. MEASUREMENT UNCERTAINTY

10.1. Model equation

uCw L

=√∑ (dwLdn )2

. (un )2



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Where wL is the liquid limitn is the components

10.2. The components10.2.1. ∆ moisture content10.2.2. ∆ standard error of linear regression10.2.3. ∆ repeatability10.2.4. ∆ reproducibility10.2.5. ∆ interlab comparison

10.3. Calculation for individual components10.3.1. ∆ moisture content, ucwL10.3.1.1. ucwLrefer to para 10.610.3.2. ∆ standard error of regression, usteyx

10.3.2.1. usteyxrefer to para 10.12

10.3.3. ∆ repeatability, urepeatability

10.3.3.1. urepeatability=Srepeatability

2 x √3

Where,urepeatability is type A standard uncertaintySrepeatability is the maximum difference among the 3 readings observed and assumed rectangular distribution.

10.3.4. ∆ reproducibility, ureproducibility

10.3.4.1. ureproducibility=Sreproducibility

2x √3

Where,ureproducibility is type B standard uncertainty



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Sreproducibility is the deviation among all staffs competent to conduct the test and assumed rectangular distribution.

10.3.5. ∆ interlab comparison, uPT

10.3.5.1. uPT=SPT

2 x√3

Where,uPT is type B standard uncertaintySPT is the deviation between average of interlab comparison and the laboratory and assumed rectangular distribution.

10.4. Combined Standard Uncertainty, ucwL

10.4.1. uCw L

=√∑ ( dwLdn )2

. (un )2

Where,

10.4.1.1.dwL

dmoisturecontent=1

10.4.1.2.dwLdSER

=1

10.4.1.3.dwL

drepeatability=1

10.4.1.4.dwL

dreproducibility=1

10.4.1.5.dwL

dinterlab comparison=1

10.4.2.uCW L

=√∑ umoisture2+usteyx

2+urepeatability2+uinterlab comparison

2

urepeatability2+ureproducibility

2



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10.5. Expand the combined standard uncertainty to 95%

10.5.1. U=ucwL . k

Where,U is the expanded uncertaintyk = 2 refer to ISO Guide to the Expression of Uncertainty in Measurement, 1995, clause 6.3.3

10.6. Uncertainty for Moisture content w

w=m2−m3

m3−m1x100 %

10.6.1. Replace r=m2−m3

10.6.2. s=m3−m1

w=100 rs

10.7. Combined standard uncertainty, uCW

uCW=√∑( dWdn )2

. (un )2

Where W is the moisture content n is the components

uCW=√∑( dWdr .ur)2

+( dWds .us)2



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Where,

10.7.1.dWdr

=100s

10.7.2.dWds

=−100 rs2

10.8. uCW=√∑( 1s. ur)

2

+(−100 rs2 .us)

2

10.9. The components for moisture content10.9.1. ur obtain from para 10.1010.9.2. us obtain from para 10.11

10.10. Calculation for ur10.10.1. Given that r=m2−m3

10.10.2. Combined standard uncertainty, ur

ur=√∑ ( drdn )2

. (un )2

10.10.3. ur=√∑ ( drdm2 )2

.(um2 )2+( drdm3 )

2

.(um3 )2

Where,

10.10.3.1.drdm2

=1

10.10.3.2.drdm3

=1



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10.10.4. ur=√∑ um2

2+um3

2

10.10.5. Combined standard uncertainty, um2

10.10.6.

um2=√∑ ( dm2

dn )2

. (un )2

10.10.7.

um2=√∑ ( dm2

dReference )2

. (uReference )2+( dm2

dCorrection )2

. (uCorrection )2

Where,

10.10.7.1.dm2

dReference=1

10.10.7.2.dm2

dCorrection=1

10.10.8. Therefore um2=√∑ uReference

2+uCorrection2

10.10.9. ∆ Reference , ureference

10.10.9.1. ureference=S1

k1

Where,ureference is type B standard uncertaintyS1 is the expanded uncertainty of the balance obtain from calibration certificate, K1 is the coverage factor obtain from the calibration certificate

10.10.10. ∆ Correction , ucorrection



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10.10.10.1. ucorrection=S2

2 x√3

Where,ucorrection is type B standard uncertaintyS2 is the correction factor given in the calibration certificate and assumed rectangular distribution.


10.10.12.

um3=√∑ ( dm3

dn )2

. (un)2

10.10.13.

um3=√∑ ( dm3

dReference )2


dCorrection )2

. (uCorrection )2

Where,

10.10.13.1.dm3

dReference=1

10.10.13.2.dm3

dCorrection=1


2+uCorrection2



k3

Where,ureference is type B standard uncertainty



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S3 is the expanded uncertainty of the balance obtain from calibration certificate, K3 is the coverage factor obtain from the calibration certificate



2 x√3


10.11. Calculation for us10.11.1. Given that s=m3−m1

10.11.2. Combined standard uncertainty, us

us=√∑ ( dsdn )2

. (un )2

10.11.3. us=√∑ ( dsdm3 )2

.(um3 )2+( dsdm1 )

2

.(um1 )2

Where,

10.11.3.1.dsdm3

=1



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10.11.3.2.dsdm1

=1

10.11.4. us=√∑ um3

2+um1

2


10.11.6. Refer to para 10.6.11


10.11.8.

um1=√∑ ( dm1

dn )2

. (un )2

10.11.9.

um1=√∑ ( dm1

dReference )2


dCorrection )2

. (uCorrection )2

Where,

10.11.9.1.dm1

dReference=1

10.11.9.2.dm1

dCorrection=1


2+uCorrection2



k5

Where,ureference is type B standard uncertainty



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S5 is the expanded uncertainty of the balance obtain from calibration certificate, K5 is the coverage factor obtain from the calibration certificate



2 x√3


10.12. Calculation for usteyx10.12.1. usteyx is calculated from the formula in the excel

function (=styex)

Where,



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This is type A standard uncertainty since the graph is plotted through data obtain from the experiment.

11. ATTACHMENT



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Wi- 03 Plastic Limit

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