Test Works in Civil Engineering

7/30/2019 Test Works in Civil Engineering

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TEST WORK in CIVIL Engineering

INDEX 12



SL. NO EXPERIMENT NO PAGE

NO.

1 Determination of Normal Consistency of Cement 2

2 Determination of Initial Setting Time of Cement 63 Determination of Fineness of Cement by Sieving 10

4 Determination of Gradation of Sand by Sieve Analysis 13

5 Workability of Concrete-Slump Test 18

6 Workability of Concrete-Compacting Factor Test 22

7 Determination of pH 26

8 Measurement of Total Dissolved Solids in Sewage 28

9 Determination of Conductivity 30

10 To Determine the Coefficient of Discharge (Cd) for

Venturi meter

33

11 Determination of Atterberg Limits 38

EXPERIMENT NO: 1 Determination of Normal Consistency of Cement

AIM: To Determination of Normal Consistency for a Given Sample of Cement.

PERFORMANCE OBJECTIVES:

a) To define the Normal Consistency of Cement

b) To prepare a Cement paste

c) To set up the experiment

d) To follow the procedural steps with precautions

e) To fill up the observation table appropriately

f) To report as per instruction 12



THEORY:

Normal Consistency of Cement is defined as a percentage of water by weight of cement which

produces a cement paste of standard consistence permitting a standard plunger of 10 mm diameter

to penetrate up to a depth of 5 mm to 7 mm above the bottom of Vicat’s Mould. The percentage

of water in the cement paste for standard consistency will vary from cement to cement and from batch to batch of the same cement. Standard consistency generally ranges from 26 to 33

expressed as a percentage by weight of dry cement. Many times higher normal consistency values

are observed for old cement of the cement is 100 fine (very high specific surface area)

NECESSARY INSTRUMENTS/EQUIPMENT USED:

1) Vicat-apparatus with plunger of 10 mm diameter and 50 mm long and Vicat’s mould withmild steel base plate.

2) Balance with weights (capacity 1 Kg, sensitivity up to 0.1 gm)

3) Trowel (small, weighing about 210 gm)

4) Marble stone slab (non-porous plate)

5) Enamel through

6) Measuring glass (100 c.c. -2 nos.)

7) Thermometer range 50oc

8) Stop Watch

9) Standard spatula

SPECIMEN SUPPLIED:

Portland cements 400 gm (for each trial)

PREPARATION OF CEMENT PLASTE:

a) Weight about 400 gm of dry cement accurately and place it in the enamel trough

b) Add 25% of clean water and mix it uniformly by means of spatula

c) Care should be taken that the time mixing (gauging) is not less than 3 minutes and not

more than 5 minutes. The gauging time shall be counted from the instant of adding water to the dry cement until commencing to fill the mould.

EXPERIMENTAL SET UP:The Vicat plunger, made up of polished brass, 10 mm diameter, 50 mm long with athreaded projection at the upper end for fixing into the movable rod and also having thelower edge flat, shall be fixed to the Vicat-apparatus in proper position. The plunger whenresting on the non-porous plate at the bottom of the mould should indicated a reading of zero in its scale.

12



Fig -1 Different Types of VICAT Apparatus

PROCEDURE:

1) Fill the Vicat-mould with the cement paste, the mould resting on marble slab or non- porous plate

2) Make the surface of the cement paste in level with the top of the mould with a trowelweighing about 210 gm. The mould should be slightly shaken to expel air bubbles.

3) Place this mould together with the non-porous plate under the rod bearing the plunger.Bring the bottom of the plunger gradually to the surface of the cement paste.

4) Release the plunger quickly, allowing it to sink into the paste. A reading of 5 to 7 mm isdesired for normal consistency of the cement paste. In case the reading is differentcontinue with the following steps.

5) Prepare trial pastes with varying percentages of water and the test as described above untildie plunger penetrates up to a depth 5 mm to 7 mm above die bottom of die mould.

6) Indicate this amount of water as a percentage by weight of dry cement (normalconsistency)

PRECAUTIONS:

12

a. Reversible stainless steel plunger with 10mm dia. on one end andthreaded

b. Plunger assembly with adjustableindicator weighs 300g with 17.5mmneedle attached and 400g with 2mmneedle

c. Modified Vicat Cone Penetrometer 10cm scale, attached aluminium coneand plunger



1) The temperature of cement, water and that of the test room at the time of test should be between 25o to 29oc.

2) Appliances to be used for gauging should be neat and clean.3) The gauging time must be between 3 to 5 minutes.4) In filling die mould, the operator’s hands and die blade of the trowel along-e be used.5) Plunger and mould must be clean for each trial.

OBSERVATION TABLE:

Sl. No.

Type of Cement

Manufactured by

Weight of CementSample

Quantityof Water Added

Percentage of Water Added

UnpenetratedDepth in mm.

Remarks

1

2

3

PPC UltratechCement Ltd.

450

450

450

450 x 0.35

450 x 0.37

450 x 0.37

35%

37%

37%

10

8.2

6.5

Desirablevalue has

beenobtained at38% water

by wt. Of cement

Hence, standard consistency of cement is 38%

REFERENCES:IS: 269-1989 specification for 33 grade ordinary Portland cement

• IS: 4031 (Part-IV) – 1988 determination of standard paste

• Concrete technology – by M.L. Gambhir, Tata McGraw Hill Publication

EXPERIMENT NO: 2 Determination of Initial Setting Time of Cement

AIM: To Determination the Initial Setting Time of a Given Cement Sample.


a) To explain the theory of setting of Cement

b) To explain initial and final setting time.

c) To prepare a cement paste.

d) To set up the apparatus.

e) To follow the procedural steps with precautions.

f) To fill up the observation table appropriately.

g) To report as per instruction

THEORY:

The term setting of cement is used to describe stiffening of cement paste. When cement is mixed

with water, the three main compounds of cement i.e., tri-calcium silicate (C3S), tri-calcium

aluminates (C3A), and di-calcium silicate (C2S), react with water. C3S hydrates more rapidly and

develop early strength, generates heat more rapidly and has less resistance to chemical attack.Whereas C2S hydrates and hardens slowly; it adds to ultimate strength and provides more12



resistance to chemical attack. C3A is fast reacting and large amount of heat generates and causes

initial setting. The phenomenon of changing from fluid state to a rigid state is called setting of

cement. Hardening of cement due to its hydration, which results in strength development, is

different from setting. In concrete construction work it is specified that the plastic concrete should

be placed and consolidated before die initial setting has occurred. It should not be disturbed until

it has hardened, the initial setting time should not be too small and therefore the standards specifythe minimum initial setting time. After initial setting, the concrete becomes rigid at final setting

and thereafter through hardening attains strength rapidly; so there is minimum of delay before side

shuttering can be removed. The setting time measures the time taken for the cement paste to offer

a certain degree of resistance to die penetration of a special attachment pressed into it. Two

periods of times are used to assess the setting behaviour. These are called initial setting time and

the final setting time. The terms initial and final set, are used to describe arbitrarily chosen stages

of setting.

Initial setting time is defined as the period or the time starting from the instant of mixing of water

to a state at which the cement paste loses its plasticity. It indicates the end of slow and steady rate

of chemical reaction after which rapid rises in temperature occurs due to faster rate of chemical

reaction. Practically it is defined as the period elapsing between the time when the water is added

to the cement and the time at which a needle of 1 mm square section penetrates no deeper than to

a point 5mm ± 0.5 mm from the bottom of the Vicat apparatus mould with the cement paste.

Initial setting time (minimum) as specified by ISI is 30 minutes for ordinary and rapid hardening

Portland cement and 60 minutes for low heat cement.

The final setting time is the time which is taken to reach the stage when the paste in the die

becomes a rigid mass. Practically it is defined as the period elapsing between the time when water

is added to the cement and the time at which the needle makes an impression on the surface test

block while the annular attachment fails to do so. Note the difference between the attachments for determining the initial and final setting time.

Final setting time (maximum) is 600 minutes for all types of cement according to IS specifications

(269-1989, IS 6909-1990, IS 1489-1991)

Final setting time chemically implies a maximum rise of temperature in die sample. The

Phenomenon of abnormal premature hardening of concrete or cement within a few minutes of

mixing of water is called false setting of cement. In this case not much heat is evolved and

remixing without additional water gives the required workability and die cement sets in die normal

manner with no appreciable loss of strength. There is no relationship between setting time and

rate of strength development of concrete. Final setting time is approximately equal to 90+1.2

times initial setting time for normal Portland cement at room temperature.


1) Vicat’s apparatus with mould and non-porous plate as per IS: 4031 (part-v) – 1988shown in fig.

2) Needle (C) for initial setting time and needle (F) for final setting time.

3) Balance (capacity 1 Kg, Sensitivity 0.1 gm)

4) Trowel (weighing about 210 gm)

5) Enamelled tray12



6) Standard spatula

7) Stop Watch

8) Thermometer

9) Measuring cylinder, 2 nos. (100 c.c.)

Materials Used: Cement (ordinary Portland) and water

PROCEDURE:

1. PREPARATION OF CEMENT PASTE (SAMPLE):

Weigh 400-450 gm of ordinary Portland cements accurately (W) having standardconsistency (P). The water which is to be added in the above weighed cement is: 0.85times the percentage of water required for the standard consistency i.e. 0.85XPXW. Startthe stop watch at once, when the water is added in the cement. Mix it uniformly with

spatula over a glass plate. The mixing or gauging time of cement water is not more than 3minutes and not more than 5 minutes. It is counted from the instant of adding water to drycement up to the filling of the mould.

2. DETERMINATION OF INITAL SETTING TIME:

i) The cement paste as prepared above is filled in Vicat’s mould, which is rested a non- porous plate.

ii) Smooth off the upper surface of the paste, making it level with the top of the mould togive the test block.

iii) The mould resting on non-porous plate is placed under the rod bearing the needle (C) asshown in Fig. 2.

iv) Lower the needle gently in contact with the surface of the test block and quickly releasethe needle allowing it to penetrate into test block. In the beginning the needle (C) willcompletely pierce the test block.

v) Repeat this procedure until the reading becomes 5+ 0.5 mm, measured from die bottom of the mould.

vi) Note the initial setting time.

vii) Record the time in the observation table.

Final set needle

Plunger

12



Initial set needle

Mould with Cement

Paste

Fig -2 VICAT’S APPARATUS

OBSERVATION:

Weight of cement (C) gm 450 gm

Standard consistency of Water (P) 38 %

Weight of water to be added 0.85 x C x P = 0.85 x 450 x 0.38 = 145.35

Sl No. Time in minutes Vicat’s apparatus reading

1 3 02 10 0

3 15 0

4 20 1.5

5 25 2

6 31 5

Time for initial setting = 31 minutes

PRECAUTIONS:

1) Needle should be cleaned every time before use.

2) Proper needle is fixed for initial final setting time.

3) Release the needle gently after it comes in contact with the surface of test mould.

4) Gauging time should not be less than 3 minutes and not more than 5 minutes.

5) Check up the stopwatch for accuracy

6) Shift the position of the mould after recording the penetration reading so that the penetration may not be at same place.

7) Test block should be performed away from vibrations and other disturbances.

CONCLUSION/DISCUSSION:

After doing this test in laboratory compare the observed values with the standard values for thetype of cement which is used by you and give your comments on the suitability of using thecement sample tested by you at construction site.

REFERENCES:

• IS: 269-1989 specification for 33 grade ordinary Portland cement 12



• IS: 4031 (Part-IV) – 1988 determination of standard paste


• Properties of concrete by A.M. Neville, ELBS Publication.

EXPERIMENT NO: 3 Determination of Fineness of Cement by Sieving

AIM: To Determination the Fineness of Cement by Sieving


a) To explain the reaction of water with cement particles

b) To explain the phenomena of hydration and rapid hardening due to greater fineness

c) To explain the link of fineness of cement with gypsum and shrinkage

d) To set up the apparatus

e) To follow the procedural steps with precautions.

f) To record the observations appropriately.g) To prepare a report as per instruction

THEORY:

Strength development of concrete is the result of the chemical reaction of water with cement

particles. The reaction always starts at the surface of the cement particles. Thus larger the surface

area available for reaction, greater is the rate of hydration and strength development. Rapid

development of strength requires greater degree of fineness. Rapid hardening cement, therefore,

requires greater degree of fineness.

However, two much fineness is also undesirable because the cost of grinding the cement to higher

fineness is considerably high. Finer cement deteriorates more quickly when exposed to air and

likely to cause more shrinkage, but less prone to bleeding. Greater fineness also requires greater

amount of gypsum for proper retardation of setting. Fineness of cement is controlled by minimum

specific surface area defined as surface area of cement particles per gram of cement. For ordinary

Portland cement the specific surface area should not be less than 2250 cm2/g. Checking fineness

of cement through sieving is an indirect method and it is easily done in the laboratory. It also

indicates if lumps have formed in cement due to poor storage & chemical reaction with moisture

from the air of the ambient environment, however specific surface area of cement can be

measured by Blaine’s air permeability co area of cement apparatus.

NECESSARY INSTRUMENTS/EQUIPMENT USED: 12



1) Analytical balance – capable of reproducing results within 0.0002 gm with an accuracy of ± 0.0002 gm.

2) Wire cloth test sieve of sue 90 microns (90μ) conforming to IS: 460 (Part-I) - 1985

3) Standard weights4) Brush – nylon or pure bristle brush preferably with 25 to 40 mm bristle for cleaning the

sieve

5) Trowel

6) Tray of size 300 x 300 mm

Fig.-3, A: Wire cloth test sieve, B: Brush , C: Analytical Balance

SPECIMEN SUPPLIED:

The samples of the cement shall be taken according to the requirements of IS: 3535-1986 and therelevant standard specification for the type of cement being tested. The representative sample of cement selected shall be thoroughly mixed before testing.

PROCEDURE:

1) Weight accurately 100 gm of cement and place it on a standard IS sieve 90 microns.

2) Break down any air set lumps in the sample with finger but does not rub on the sieve.

3) Continuously sieve the sample by holding the sieve in both hands and giving a gentle wrist

motion or mechanical sieve shaker may be used for this purpose. The sieving should becontinuous for 15 minutes. 12

A C

B



4) Weight the residue left after 15 minutes sieving. This residue shall not exceed the specifiedlimits as follows:

After sieving the residue by weight on 90 μ IS sieve not to exceed 10% for ordinarycement and 5% for rapid hardening cement

OBSERVATION:

Description of items Sample I Sample II Sample III

Weight of cement W (gm) 100 100 100

IS Sieve size (μ) 90 90 90

Sieving time (minutes) 15 15 15

Weight retained on sieve W1 (gm)

11 12 14

Percents weight retained onsieve

11% 12% 14%

Mean percentage 12.33%

REMARKS:

As the cement is partially hydrated few portion has formed lumps due to which is more than ten.

PRECAUTIONS:

1) The cleaning of the sieve should be done very gently with the help of a brush i.e. 25 mm or 40 mm birds brush with 25 cm handle.

2) After sieving die cement must be removed from the bottom surface of the sieve gently.3) Weighing machine must be checked before use.

4) Sieving must be carried out continuously.

REFERENCES:

• IS: 3535 (Part-I) -1986 Methods of sampling of hydraulic cement (first revision)

• IS: 4031 (Part-I) – 1988 determination of standard paste

•

Concrete technology – by M.L. Gambhir, Tata McGraw Hill Publication• Properties of concrete by A.M. Neville, ELBS Publication.

12



EXPERIMENT NO: 4 Determination of Gradation of Sand by Sieve Analysis

AIM: To Determination the Gradation of Sand by Sieve Analysis


a) To explain the theory of particle size distribution (Grading)

b) To collect die true representative sample from stock pile

c) To set up the experiment

d) To follow the procedural steps with precautions.

e) To fill up the observation table appropriately

f) To plot the particle size distribution curve (Grading curve)

g) To report as per instruction

THEORY:

Sieve analysis is a mechanical process of separating aggregate (here sand) into its different size

fractions by sieving or screening through a series of test sieves in order to determine the grading

of particle size distribution i.e., proportion of particles of different sizes. Sand as a fine aggregate

for concrete and mortar should be well graded on the principle that the smaller particles shall fill

the voids between larger particles leaving minimum voids that are supposed to be filled up by the

cement particles in the resulting mass. For normal structural purposes the grading shall be within

the limits specified in IS: 383-19/0. The sieves that are to be used for the sieve analysis of fine

aggregate (sand) as per IS: 2306 (Part-I)-1963 are 4.75mm, 2.36mm, 1.18mm, 600 μ m, 300 μ

m, 150 μ m, & 75 μ m. The sieves arranged in such an order that the square openings are nearly

half for each succeeding smaller size.

The curve showing die cumulative percentage of die material passing the sieves represented on die

ordinate and with the sieve openings plotted to a logarithmic scale represented on the abscissa istermed as the grading curve. The grading curve indicates whether die grading of a given sample

confirms to that specified or is too coarse or too fine, or deficient in a particular size.

Fineness Modulus (P.M.) of fine aggregate (sand) is an approximate numerical index of fineness,

giving some idea of the mean size of the particles present in die entire body of the aggregate.

Larger die value, the larger is the average size approximately. It is defined as the sum of the

cumulative percentages retained on the sieves (from 4.75 mm to 150 μ) divided by 100. The

fineness modulus can be looked upon as a weighted average size of a sieve on which the material

is retained, the sieve being counted from the finest, However, it should be kept in mind that one

parameter, the average, cannot be representative of a distribution: thus the same fineness moduluscan represent or infinite number of totally different size distribution of grading curves, it is not12



much used in India now-a-days, but it is valuable for measuring slight variations in the aggregate

from the same source.

Standard grading zones or limits of percentages passing different sieves are available for proper

grading of sand is grading zones I, II. III, & IV as shown in Table below reproduced from IS:

383-1970, Coarse sand is suitable for making concrete where as finer sand can be used for smooth plastering of masonry or concrete surface. But mortar with coarser sand is stronger than mortar

with finer sand for same proportion of cement to sand ratio and workability.

Table Showing Percentages of Sand Passing Sieves for Different Grading Zones:

IS Sieve

Designation

Grading Zone

I

Grading Zone

II

Grading Zone

III

Grading Zone

IV

10 mm 100 100 100 100

4.75 mm 90-100 90-100 90-100 95-100

2.36 mm 60-95 75-100 85-100 95-100

1.18 mm 30-75 55-90 75-100 90-100

600 μ 15-34 35-59 60-79 80-100

300 μ 5-20 8-30 12-40 15-50

150 μ 0-10 0-10 0-10 0-15


1) A set of IS-Sieves (of 4.75 mm, 2.36 mm. 1.18 mm, 600 microns, 300 microns, 150

microns, 75 microns) with a lid at top and receiving pan at the bottom.

2) A weighing balance or scale of 5 kg capacity accurate to 0.1 percent the weight of die testsample.

3) A sieve shaking machine

4) Soft brush, tray, duster, stopwatch etc.

12



Fig.-4, A: Automatic sieve shaking machine, B: Wire cloth test sieve, C: Analytical Balance

MATERIALS & PREPARATION:

a) Cool die oven dry (100oC-110oC) sample to room temperature. Take about 1 kg from it, by quartering and break the lumps if any.

b) Check the accuracy of the balance.

c) Check the sieve sizes and order.

d) Clean the sieves and the receiving pan.

PROCEDURE:

1) Weigh out 500 gm of the sample prepared for testing = W gm.

2) Weigh each sieve = W1 gm. Weigh also the receiving pan and keep a record.

3) Set die sieve in order with the largest sieve (4.75 mm) at the top, put the receiving pan atthe bottom of 75 microns sieve.

4) Place the weighed sample into the top sieve put the lid over it.

5) Put the whole assembly on the sieve-shaking machine and shake for 10 minutes.

6) Weigh each sieve along with the hand retained on it = W2 (gm)

7) Find out:a.) The weight of the sample retained on each sieve = W2-W1 = W3 (gm)

b.) The Percentage of total sample by weight retained on each sieve P = (W2-W1 )/W x100 %

c.) Fine the cumulative percentage by weight of total sample retained on each.

12

A

B

C



8) Add up the cumulative percentage for sieve sizes 4.75 mm, 2.36 mm, 1.18 mm, 600 μ,300 μ & 150 μ only and divide it by 100 to obtain Fineness Modulus (F.M)

9) Check the weight of sample retained on sieve and receiving pan with that of test sampletaken (W)

OBSERVATION:

Weight of the sand taken, W = 500 gm.

Observation Table for a Sample of Sand:

Sieveorder

No.

IS Sieve size Wt. SandRetained(W2-W1)(gm)

Percentage of WeightRetainedP = (W2-W1 )/W x 100 %

CumulativePercentageRetained

CumulativePercentagePassing

Remarks

1 4.75 mm 3 0.6 0.6 99.4 1. Oven dry sand cooledto room temp. was tested.

2. Shaking of sieve wasdone by shakingmachines

2 2.36 mm 8 1.6 1.22 98.78

3 1.18 mm 41 8.2 9.72 90.284 600 micron 116 21.2 30.92 69.08

5 300 micron 244 48.8 79.72 20.28

6 150 micron 88 17.8 97.52 2.48

Total = 500 (gm) 219.70

PRECAUTIONS:

1) Aggregate sample should he air-dried to prevent clogging in sieves.

2) Finer sieves should be cleaned gently with soft brushes

3) Care should be taken to see that the sieves are not surcharged. The Weight of sand sampleshould not exceed 500 gm

4) Sieving should be done by giving varied motion so that each particle gets sufficient chanceof passing through the sieve opening (if done manually)

RESULTS:

Size of sand at:

i). 10 % finer than (D10) = 0.22 mm

ii). 60 % finer than (D) = 0.54 mm

iii). D60/D10 = uniformity co-efficient, Cu = if> 4 well graded otherwise poor aggraded.

iv). Fineness Modulus (F.M) = 2.197

Hence the sand is fine sand 12



CONCLUSION/DISCUSSION:

Comment on test results obtained by you in laboratory (well graded/Gap graded/uniformitygraded).

Give your comments on the suitability of using the cement sample tested by you at constructionsite.

REFERENCES:

• IS: 2386 (Part-I) -1963 Methods of test for aggregates for construction Part-I particle size

and shape

• IS: 383-1970 specification for coarse fine aggregates from natural sources for concrete.

•

Concrete technology – by M.L. Gambhir, Tata McGraw Hill Publication• Properties of concrete by A.M. Neville, ELBS Publication.

EXPERIMENT NO: 5 Workability of Concrete – Slump Test

AIM: To Determination the workability of concrete by Slump Test


a) Define workability

b) State the important properties of concrete related to workability

c) Set up the apparatus and prepare sample

d) Follow the procedural steps with precautions.

e) Record the observation appropriately 12



f) Report as per instruction

THEORY:

Workability is the ease with which concrete mix flows to the remotest corner of the formwork. In

more scientific term it is the property of the concrete, which determine die amount of usefulinternal work necessary to produce full compaction. But in practice various requirements such as

mixability, stability, transportability, placeability, mobility, compactability and finishability etc. are

collectively referred to as workability. IS:6461 (Part-VII)-1973 defines workability as that

property of freshly mixed concrete or mortar which determine the ease and homogeneity with

which it can be mixed, placed, compacted and finished. For full compaction concrete mix should

posses three important properties adequately viz. Mobility, cohesiveness and absence of hardness.

Water is the most important factor, winch affect mobility, but higher W/C ratio reduces the

strength of concrete. Too much of water may lead to segregation and loss of cohesiveness and

homogeneity. Similarly adopting coarser grade of aggregate can reduce internal friction.

Harshness in concrete is mostly due to presence of too much of coarse aggregate specially if the

coarse aggregate is flaky in nature. Harshness can be eliminated if there is adequate proportion of

mortar to fill the voids in the coarse aggregate, but this involves additional cost because of

increased consumption of cement. Factors including W/C ratio remaining constant, using a high

amount of cement per unit volume of concrete can increase the workability of a concrete mix.

Therefore, a good quality of concrete is to be obtained by appropriate proportioning of coarse

and fine aggregate as well as cement while the W/C ratio is fixed from compressive strength of

concrete criteria. Depending on narrowness of a section and its reinforcement content more

congested section demand higher values of workability.

There is really no unique method, which can measure the workability of concrete in its totality anumber of empirical tests are available for checking uniformity of workability of freshly mixed

concrete . Each test measures one or few aspect of workability but slump test despite some

limitations, is a very simple and common one in use. The test is more useful to ensure the

uniformity of a concrete mix by measuring consistency or wetness rather than measuring the

actual workability of concrete.

NECESSARY INSTRUMENTS/EQIPMENT USED:

1) A mould of metal of thickness 1.6 mm in the form of a frustum of a cone with top and

bottom open and a smooth inter surface as shown in Fig. below. It is also provided withfoot pieces and handles.

2) Tamping rod of steel 0.6 m long and 16 mm diameter with one end rounded.

3) Trough, trowel, G.I plain sheet, steel scale.

12



K Slump Tester

Slump Test Sets for Concrete Testing

Fig.-5

SPECIMEN:

Concrete mix, as per given proportion, is to be prepared by weight or volume as directed by the teacher.

PROCEDURE:

1) Clean the internal surface of the mould and place it on a smooth, horizontal, rigid and non-

absorbent surface such as a levelled metal plate.

2) Fill the mould in four layers each with approximately one quarter of height compactedwith 25 strokes of tamping rod on each layer uniformly distributed.

3) Concrete shall be struck off level with a trowel at die top surface.

4) The mould should be removed from the concrete immediately by raising it slowly findscarefully in a vertical direction.

5) Measure the subsidence concrete or slump immediately from highest point of specimen.

6) The test shall be carried out at a place free from vibration or shock, within a period of 2minutes after maxing.

Fig.- 6 Schematic of the Modified Slump Test

12



True Zero Collapsed Shear

Fig.- 7 Different Types of Slumps

Cement taken 4.4 kg

Sand taken 7.61 kg

Coarse aggregate taken 7.61 kg

Water taken 2.29 kg

Slum value = 300-275 = 25 mm

REMARKS:

The work ability of this concrete is very low well mass concreting of foundation havinglight reinforcement

PRECAUTIONS:

1) The test shall be carried out at a place free from vibration within two minutes after mixingof concrete it if it is field test and it can be done within 10 minutes after mixing if it is alaboratory test.

2) If slump collapse or shears off laterally as shown in Fig.7 above, test may be repeated, andif again similar results are obtained, the fact should be recorded. The slump is to be12



measured along the longitudinal axis of the cone. In normal cases the slump should look infig. earlier.

REFERENCES:

• IS: 3535 (Part-I) -1986 Methods of sampling of hydraulic cement (first revision)

• IS: 4031 (Part-I) -1988 determination of standard paste.


EXPERIMENT NO: 6 Workability of Concrete – Compacting Factor Test

AIM: test for workability (COMPACTING FACTOR TEST)


a) To define the term workability

b) List different tests for determining workability

c) To explain compacting factor test and the principle on which it works.

d) To find out the compacting factor

e) To set up the experiment

f) To follow the procedural steps with precautions.

g) To fill up the observation table appropriately

h) To report as per instruction

THEORY:

The workability of a freshly mixed concrete can be defined as the amount of useful internal work

necessary to produce full compaction. But in practice various requirements such as mixability,stability, transportability, placeability, mobility, compactability and finishability etc. are12



collectively referred to as workability. IS:6461 (Part-VII)-1973 defines workability as that

property of freshly mixed concrete or mortar, which determines the ease and homogeneity with

which it can be mixed, placed, compacted and finished.

There is no really unique method, which can measure die workability of concrete in its totality. A

number of empirical tests are available for checking uniformity of workability of freshly mixedconcrete. The empirical tests, which are widely used in finding die workability, are:

1) Compacting factor test2) The slump test3) The Vee-Bee consistency test4) The flow test

Each test measures one or a few aspects of workability. Compacting factor test is one of suchavailable test. The method uses an inverse approach; the degree of compaction achieved by astandard amount of work by allowing the concrete to fall through a standard height is determinedrather than measuring the amount of work necessary to achieve full compaction. The method isespecially suitable in die case of relatively dry concrete mix which is insensitive to slump test. Thistest evaluates a factor known as compacting factor.The compacting factor for a fresh concrete is defined as the ratio of the density actually achievedin the test to the density of same concrete fully compacted. For a container of constant volume,the compacting factor, as in rest is defined as the ratio of the weight of partially compactedconcrete in die cylinder at bottom under standard height of fall to the weight of equal volume of compacted concrete.

Suggested ranges of workability of concrete for different conditions of placing as per IS: 456(Part-III)-1978 and IS: 1199-1959:

Sl.

No

Placing Condition Degree of workability Compacting factor

1 Concreting of small section with vibrations Very low (stiff) 0.5-0.80

2 Concreting of lightly reinforced section with

vibrations

Low (stiff plastic) 0.80-0.85

3 Concreting of lightly reinforced section without

vibrations or heavily reinforced section without

vibrations

Medium (plastic) 0.85-0.92

4 Concreting of heavily reinforced section withoutvibrations

High (flowing) More then 0.92

REMARKS:Hence the degree workability medium plastic


Compacting factor apparatus as per IS: 1199-1959 is shown in Fig. 8

12



Fig. 8 Compacting factor apparatus

1.) The apparatus consists of three parts i.e. upper hopper, lower hopper and cylinder. These areof rigid construction to true shape and smooth finish from inside. These shall be made of cast

brass or bronze, but stout sheet of brass or steel may also be considered satisfactory provideddie inside surface of die joints are smooth and flush. 3 mm thick metal plate trapdoor ishinged tightly at die lower ends of hopper having quick release catches. The following are thedimensions of compacting factor apparatus used for the aggregate not exceeding 38 mm

nominal maximum size.

Details Dimension in mmUpper hopper A:

Top internal diameter 254Bottom internal diameter 127Internal height 279

Lower hopper B:Top internal diameter 229Bottom internal diameter 127

Internal height 229

Cylinder C:Internal diameter 152Internal height 305

Distance between bottom of upper hopper andTop of lower hopper 203And top of cylinder 203

a) Length of hand scoop 152 b) Stop watch

c) Tamping rod of diameter 16 mm and length 610 mmd) Platform weighing machine 1 no.

12



MATERIAL USED:

Cement, Sand, Aggregate, Water

PROCEDURE:

1) Take the sample with required proportions by weight or by volume with specified water cement ratio as direction by the teacher.

2) Apply a thin layer of petroleum jelly to the whole apparatus internally.

3) Place the sample of concrete gently in the hopper with a hand scoop without any

compaction. Fill up the concrete in level with brim.

4) Open the trap door so that the concrete falls into lower hopper.

5) If the concrete sticks to the sides of the hopper push it gently with help of rod from top.

6) Open the trap door of the lower hopper and allow the concrete to fall into the cylinder.

7) Remove excess concrete remaining above the level of the top of the cylinder stuck off bytrowel.

8) Clean the cylinder from outside and weight it to the nearest 10 gm

9) Refill the cylinder from the same sample of concrete in layers approx. 50 mm deep, everylayer is being heavily rammed by giving 25 blows with tamping rod or vibrated so as toobtain full compaction.

10) Clean the cylinder from outside and weight it again.

11) Record all the observation in the observation table

OBSERVATION TABLE:

Sl. No Particulars Specimens

1

a) Weight of cylinder W1 kg 6.3

b) Weight of cylinder concrete falling through standard

height = W2 kg

18.18

c) Weight of concrete (W2

-W1

) = W3

kg 18.18-6.3 = 11.88d) Weight of fully compacted concrete = W4 kg 19.40

e) Weight of fully compacted concrete (W4-W1) = W5

kg

19.40-6.3 = 13.10

f) Compacted factor =W3/W5 0.906

PRECAUTION:

1) Test should be performed immediately after the mixing is completed.

2) The convenient time for realizing the concrete from the upper hopper is 2 minutes after the mixing is completed.

12



3) The concrete, which sticks of the sides of hopper, should be gently pushed with the helpof tamping rod from top side.

4) Weighing should be done properly.

REFERENCES:

• IS: 1199-1959: Methods of sampling of and analysis of concrete.

• IS: 456-2000: Code of practice for plain and reinforced concrete.

• IS: 6461 (Part-VII)-1973

• Laboratory manual for concrete technology, T.T.T.I Chandigarh Publication


EXPERIMENT NO: 7 DETERMINATION OF pH

Aim: To determine the pH of given samples using (1) universal indicator (2) pH paper, and (3)digital pH meter

Principle:

pH value of water indicates the hydrogen ion concentration in water and concept of pH was putforward by Sorenson (1909). pH is expressed as the logarithm of the reciprocal of the hydrogenion concentration in moles/litre at a given temperature. The pH scale extends from 0(very acidic)

to 14 (very alkaline) with 7 corresponding to exact neutrality at 25o

C. pH is used in thecalculation of carbonate, bicarbonate and CO2, corrosion and stability index etc. While thealkalinity or acidity measures the total resistance to the pH change or buffering capacity, the pHgives the hydrogen ion activity. pH can be measured colorimetrically or electrometrically,Colorimetric method is used only for rough estimation. It can be done either by using universalsindicator or by using pH paper. The hydrogen electrode is the absolute standard for themeasurement of pH. They range from portable battery operated unites to highly preciseinstruments. But glass electrode is less subject to interferences and used in combination with acalomel reference electrode. This system is based on the fact that a change of 1 pH unit producesan electric charge of 59.1 m V at 25oC.

Apparatus:

1. pH meter with electrode2. Beaker 3. Thermometer 4. Colour comparator with dieses5. Cuvettes

12



Fig. 9 Buffer solutions and pH meter with electrode

Reagents:

1. Buffer solutions2. pH paper

3. Indicator Universal

Procedure:

a) Using Universal Indicator1. 10 ml of sample is taken in a cuvette.2. Another 10 ml sample is taken in another cuvette and 0.2 ml of universal indicator is

added and placed in the hole provide for.3. A colour disc corresponding to this indicator is inserted into the comparator and the disc

rotated such that the 2 circles colours.4. The reading is noted.

5. The procedure can be repeated using an indicator whose range is near the value obtained.6. The extra pH is obtained.

b) Using pH Paper1. Dip the pH paper in the sample.2. Compare the colour with that of the colour given on the wrapper of the pH paper book.3. Note down the pH of the sample along with its temperature.

c) Using pH Meter

1. Follow the manufacturer’s operating instruction.

2. Dip the electrode in the buffer solution of known pH

3. Switch on the power supply and take the reading. Standardize the instrument using thecalibrating knob.

4. After cleaning, again dip the electrode in the buffer solution of pH 7. Note the reading. If it is 7, in the instrument is calibrated. If not, correct the value and is manipulated so thatthe reading in the dial comas to 7.0.

5. A solution whose pH is to be found is taken in a baker and the temperature knob isadjusted such that the temperature of solution is some as that in dial.

6. The electrode is washed with distilled water and reused with the solution and then it isdipped in the solution.

7. The reading on the dial indicates the pH of the solution.

Results: 12



SAMPLE NO. pH

pH paper pH meter Remarks

1 Blue 12 Alkaline

2 Red 6.30 Acidic

3 Red 6.00 Acidic

EXPERIMENT NO: 8

Object: Measurement of Total Dissolved Solids in Sewage

THEORY:

Sewage contains 99.9% water and only 0.1% solids but the nuisance caused by them is

considerable, as they are highly putrescible (readily degradable) and therefore require proper treatment before disposal. The solids present in sewage may be classified, as suspended anddissolved solids, colloidal solids and settleable solids, which may farther be subdivided intovolatile and non volatile solids. The volatile matter is organic matter. Quantification of volatile or organic fraction of solid which is putrescible is necessary as this constitutes the load on biologicaltreatment units or oxygen resources of a stream when sewage is disposed of in a river. Thedissolved solid may be inorganic also the inorganic fraction is considered when sewage is used for land irrigation or when reuse of sewage is done for any other purpose. The measurement of totaldissolved solids in water can be done in similar way, by taking the sample, of water, in place of sewage.

Apparatus:i) Evaporating dishesii) Drying oveniii) Standard filter paper iv) Digital weighing balance (microgram)v) Conical flask vi) Measuring cylinder

Procedure:

Take 50 ml of well mixed sewage sample in a measuring cylinder. Have four folder of the

standard filter paper and fix it on the funnel placed over a conical flask. Pour the sewage gently onthe tunnel and allow it to slowly filter down through the funnel shaped filter paper. Pour itintermittently so that the filtrate is only sewage containing dissolved solids and the suspendedimpurities are filtered out.

Transfer filtrate to a weighed evaporating dish (weight say A mg) and evaporate to dryness in thedrying oven. Dry evaporated sample for 1 hr in an oven at 180 oC and cool it. Weight it say as Bmg and calculate the dissolved solids as below.

CALCULATION AND RESULT

12



where: A = weight of filter + dried residue, mg, and B = weight of filter, mg.

Comments:

The total dissolved solids give an ides about the organic and inorganic matter present in thesewage in dissolved form. Organic matter is volatile and can be determined by igniting the residueat higher temperature at 550oC. Even the total dissolved solids give a fair idea about the organicmatter and the anticipated treatment of the wastewater. Treatment means to satisfy the BOD.BOD can be satisfied aerobically or anerobically. Aerobic treatment is better as it produces lessharmful end products but it is generally costly. So depending upon the foulness (organic solidmatter) and the funds available the selector of process is done.The total dissolved solids in the give sewage sample are 650 mg remarks permissible limit of dissolve solids in water is 500 mg/L where the value obtained from this result for the sewagewaters is much better than the limit value.

12



EXPERIMENT NO: 9

Object : CONDUCTIVITY

INTRODUCTION:

The conductivity of a solution is a measure of its ability to carry an electric current and varies both with the number and type of ions the solution contains. Conductivity can be measured in aconductivity cell connected to a Wheatstone Bridge circuit. The physical measurement made in alaboratory determination of conductivity involves setting the cell constant to and using it todetermine the conductivity and hence the specific conductance (K).

The molarities of various dissolved ions, their valences and their actual and relative concentrationsafter conductivity. Most inorganic acids, bases and salts are relatively good conductors.

Conversely molecules of organic compounds that do not dissociate in aqueous solution conductcurrent very poorly.

SIGNIFICANCE:

Practical applications of conductivity measurement area:

a) Conductivity is at least as good a criterion of the degree of mineralization as the morecommonly used “total dissolved solids” for assessing the effect of diverse ions on chemicalequilibrium physical effect on plants and animals, corrosion rates etc.

b) The purity of distilled and deionised water can be checked by the determination.

c) Variations in dissolved minerals concentrations of raw water or waste matter samples can be noted.

d) Conductivity measurement allows an estimate of the sample size that should be used for the common chemical determination.

e) Conductivity measurement makes possible the determination of the amount of ionic

reagent needed in certain precipitation.

GENERAL DISCUSSION:

The standard unite of electrical resistance is Ohm (Ω). The standard unite of electricalconductance (G) is its inverse, the Siemens. Resistively is the resistance measured betweenopposite faces of a rectangular Prism and is reported in Ohms unit length. Conductivity is thereciprocal of resistance and reported in Siemens per unit length. Specific conductance is definedas the conductance of a conductor 1 cm2 in cross sectional area.

PRICIPLE:

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Commonly used instrument which is used in the conductivity test is known as the conductivitymeter. The principle involves setting the cell constant to unit reading given by the conductivitymeter can be directly read as the specific conductance of the sample

APPARATUS:

Fig. 10 Conductivity Cell

1. Conductivity Cell: Non Platinum Electrode Type

Conductivity Cell contains electrodes constructed durable metals are widely used for continuousmonitoring and field studies. Such cells are to be calibrated by comparing the conductivity of themater being tested with the result obtained with the laboratory instruments. Determination of cellconstant with KCL may introduce a significant error if the cell and instrument are not properlydesigned.

REAGENTS:

1. Standard KCL, 0.01 M 745.6 mg anhydrous KCL is dissolved in conductivity meter andmade up to 1000 m) at 25 °C. This is the standard reference solution, which at 25 °C has aspecific conductance of 1413 µmho/cm. It is satisfactory for most maters when using a cell with a

constant between 1 and 2. PROCEDURE:

1. Determination of cell constant arid conductivity of KCL solution.The KCL solution is taken in a beaker. The electrode is washed with distilled water and is

then dipped into the KCL solution. The cell constant of the instrument is set 1 and theconductivity reading is noted. Then the specific conductance of the solution is determined fromthe formula

K = C x L/A

Where, K = specific conductance of the solutionC = conductivity of the solutionL/A = Cell constant of the instrument.

12

Cell Constants Available k=0.1, k=1.0(k=10.0 available for CS200and CS200TC only)Measuring Surface Graphite (CS150) orPlatinum blackcoated platinum (CS200)Body Material Epoxy



2. Determination of the specific conductance of the matter sample.

CALCULATION: K = C x L/A K = C (L/A)

Sl. No. K C K/C C1. 1.411 X 10-3 2.25 X 10-3 0.627 0.5

2. 1.411 X 10-3 2.25 X 10-3 0.624 0.513. 1.411 X 10-3 2.25 X 10-3 0.627 0.51

1. K = 0.5 x 0.627 = 0.3132. K = 0.51 x 0.624 = 0.3183. K = 0.51 x 0.627 = 0.320

Result: The conductivity of the matter sample comes out to be 0.315 milliohms/cm

EXPERIMENT NO: 10

Object: To determine the coefficient of discharge (Cd) for Venturimeter

Apparatus:

12



Venturimeter is fitted across a pipeline leading to a collecting tank, stop watch, U-Tubemanometer connected across entry and throat sections etc.

Fig. 11 the Venturi meter operation.

Formula:

Theoretical discharge through Venturimeter

Q th = [A1 .A2 (2g.H)1/2] /[A12-A2

2] ½

Actual discharge through Venturimeter

Q ac = V/t = (A.∆ H)/t

Where:

A1: Cross section area of Venturimeter at entry section

A2: Cross section area of Venturimeter at throat section

H: Pressure head difference in terms of fluid flowing through pipeline system.

V: (A.H) i.e. Volume of water collected in collecting tank. 12

Downstream Pressure ta

UpstreamFlow

UpstreamPressure tap

Venturi Throat

DownstreamFlow



A: Cross section area of collecting tank.

H: (H2-H1) i.e. Depth of water collected in collecting tank.

t : Time required to collect the water up to a height H in the collecting tank.

Theory:

Venturimeter is a device consisting of a short length of gradual convergence and a long length of gradual divergence. Pressure tapping is provided at the location before the convergencecommences and another pressure tapping is provided at the throat section of a Venturimeter. Thedifference in pressure head between the top tapping is measured by means of a U-tubemanometer. On applying the continuity equation & Bernoulli’s equation between the twosections, the following relationship is obtained in terms of governing variables.

Qth = [A1.A2(2g.H) 1/2]/ [A12-A2

2] 1/2....................................................................... 1.

H = Hm [(ρm /ρw) – 1]

ρm & ρw be the densities of manometric liquid & fluid (water) flowing through pipeline system.

In order to take real flow effect into account, coefficient of discharge (Cd) mast be

Introduced in equation 1 then,Qac = Cd.A.(2g.H) 1/2

Therefore, Cd = Qac/Qth

Theoretical discharge is calculated by using equation 1. Actual discharge is calculated bycollecting water in collecting tank & noting the time for collection.

Qac= A. (H2 –H1)/t = V/t =(A.H) / t

Procedure:

* Note the pipe diameter (d1) and throat diameter (d2) of Venturimeter.

* Note the density of manometric liquid i.e. mercury (ñm) and that of fluid flowing through pipeline i.e. water (ñw)

* Start the flow and adjust the control valve in pipeline for maximum discharge.* Measure the pressure difference (Hm) across the Venturimeter by using U-tube

manometer.

* Measure flow rate i.e. actual discharge (Qac) through Venturimeter by means of collectingtank.

* Calculate the theoretical discharge (Qth) through Venturimeter by using the formula.

12



* Decrease the flow rate by adjusting the control valve and repeat the process for at leastfive times.

* Determine the coefficient of discharge (Cd) for each flow rate and find the mean value of coefficient of discharge (Cd) mean.

* Plot a graph of (Qac) on y-axis versus (Qth) on x-axis.

* Calculate the slope of graph of (Qac) versus (Qth), it gives mean value of coefficient of discharge (Cd) mean graphically.

Observation:

Diameter of pipe d1 = 0.025 mDiameter of throat d2 = 0.0125 mArea of collecting tank A = 0.5 x 0.3 = 0.15 m2

Area of pipe at entry, A1 = [(π/4) d12] = [(π/4) (0.025)2] = 4.908 x 10-4 m2

Area of pipe at throat, A2 = [(π/4) d22] = [(π/4) (0.0125)2 = 1.227 x 10-4 m2

Density of mercury, ρm = 13600 kg/m3

Density of water, ρw = 1000 kg/m3

Observation Table:

Sample Calculation:

For Observation No.

* Pressure head differenceH = Hm [ρm /ρw) – 1]

= 5/100 [(13600 /1000) – 1= 5/100 [12.6]= 0.63 m

* Actual discharge,Qac = (A.H) /t

= (0.15 x 0.10 /100)/ 52= 2.8846 x 10-4 m3/sec

* Theoretical dischargeQth = [A1.A2(2g.H1/2)]/ [A12-A22 ] 1/2

= [4.909 x 10-4 x 1.227 x 10-4(2 x 9.81 x 0.63)]1/2/

Sl. No

ManometricReading

PressureHead

difference

Tank Reading

Timet

ActualDischarge

Qth =A1.A2(2g.H)1/2

/ [A12-A2

2] 1/2

Cd = Qac

LeftLim

b

Right

Lim b

Diff h2- h1

H =Hm [(pm

/pw)-1]

Initial Final Diff.H2-H1

Qac =(A.H) /t

Qth

h1

mh2

mHm

mm H1

mH2

mHm

Sec m3 /sec m3 /sec

1 11.20 16.20 5 0.63 2.2 12.20 10 52 2.884 x 10-4 4.455 x 10-4 0.647

2 11.30 16.40 5.10 0.6426 1 11 10 48 3.125 x 10-4 4.499 x 1-04 0.6945

3 10.60 15.80 5.20 0.6552 1.5 11.50 10 45 3.33 x 10-4 4.453 x 10-4 0.7485

4 10.10 16.90 6.80 0.8568 2.7 12.70 10 41 3.6585 x 10-4 5.1938 x 10-4 0.704

5 9.40 17.60 8.20 1.0332 3.5 13.50 10 36 4.1667 x 10-4 5.7054 x 10-4 0.730

12



[(4.909 x 10-4)2 - (1.227 x 10-4)2]1/2 = 4.4552 x 10-4 m3/sec

* Coefficient of dischargeCd = Qac /Qth

Cd = 2.8846 x 10-4 /4.4552 x 10-4

Cd = 0.647Hence the average value of the Coefficient of discharge is 0.705.

Venturimeter

Fig. 12 the Venturi meter

PRECAUTIONS:

Flow pressure should be control in a way to active the measurable manometer difference accuracy has to bementioned. The time of scale reading of the stop watch should be handled properly to measure accuratetiming table.

12



Fig. 13 Experimental Setup to determine Cd for the Venturi meter

EXPERIMENT NO: 11

Object: Atterberg Limit: Liquid Limit and Plastic Limit of SoilsD 4318 -95

“Abstracted with permission, from the 1996 Annual Book of ASTM Standards, copyrightAmerican Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA19428-2959”

Sample Preparation Procedure for Liquid Limit:

1. Select 200 to 250 gm specimen 12



2. Adjust the water content of the specimen by adding distilled water and mixing on a glass plate with a spatula. This specimen should be close to, but not past, the liquid limit of thesoil.

3. Place the prepared soil in a container and let the specimen stand for at least 16 h.

Sample Preparation Procedure for Plastic Limit:

1. Select 20gm specimen of the same sample used for the preparation for the liquid limit test.This sample should be dry enough so that it will not be sticky.

2. Place this sample in the same container and on top of the wetter specimen.

Scope:

This test method covers the determination of the liquid limit, plastic limit and plasticity index of soils. The liquid and plastic limits of soils are often referred the as the Atterberg limits. Definitions:

Liquid Limit (LL or wL): the water content, in percent, of a soil at the arbitrarily defined boundary between the semi-liquid and plastic states.

Plastic Limit (PL or w p): the water content, in percent, of a soil at the boundary between the plastic and semi-solid states.

Plasticity Index (PI): the range of water content over which a soil behaves plastically.

Significance and Use:

This testing method is used as an integral part of several engineering classification system tocharacterize the fine-grained fractions of soils and to specify the fine-grained fraction of construction materials. The liquid limit, plastic limit and plasticity index of soils are also usedextensively, either individually or together, with other soils properties to correlate withengineering behaviour such as compressibility, permeability, compatibility, shrink-swell and shear strength.

Apparatus:

Liquid Limit Device – a mechanical device consisting of a brass cap suspended from a carriagedesigned to control its drop onto a hard rubber base. The device may be operated by either a handcrank or electric motor.

Cup – brass with mass (including cap hanger) of 185 to 215 gm.

Cam – designed to raise the cap smoothly and continuously to its maximum height, over adistance of at least 180o of the cam rotation, without developing an upward or downward velocityof the cup when the cam follower leaves the cam.

Flat Grooving Tool – a tool made of plastic or non-corroding metal having specified dimensions.

Gauge – A metal gauge block for adjusting the height of the drop of the cap to 10 mm 12



Ground Glass Plate – used for rolling plastic limit threads

Fig. 14 Liquid Limit Machine

Calibration of Apparatus:

Determine that the liquid limit device is clean and in working order. Adjust the height of the dropof the cap so that the point of the cap that comes in contact with the base rises to a height of 10 ± 0.2 mm.

12



Fig. 15 Liquid Limit Test Set

Procedure for Liquid Limit:

1. Place a portion of the prepared sample in the cap of the liquid limit device at the pointwhere the cap rests on the base and spread it so that it is 10 mm deep at its deepest pointfrom a horizontal surface over the soil. Take care to eliminate air bubbles from the soilspecimen. Keep the unused portion of the specimen in the storage container.

2. From a groove in the soil by drawing the grooving tool, bevelled edge forward, throughthe soil from the top of the cup to the bottom of the cup. When forming the groove, holdthe tip of the grooving tool against the surface of the cup and keep the tool perpendicular to the surface of the cup.

3. Lift and drop the cup at a rate of 2 drops per second. Continue cranking unit the twohalves of the soil specimen meet each other at the bottom of the groove. The two halvesmust meet along a distance of 13 mm (1/2 in).

4. Record the number of drops required to close the groove.

5. Remove a slice of soil and determine its water content, w.

6. Repeat steps 1 through 5 with a sample of soil at a slightly higher or lower water content.Whether water should be added or removed depends on the number of blows required toclose the grove in the previous sample.

Note: The liquid limit is the water content at which it will takes 25 blows to close the grooveover a distance of 13 mm. Run at least five tests increasing the water content each time.As the water content increases it will take less blows to close the groove.

Procedure for Determination of the Plastic Limit:

1. From the 20gm sample select a 1.5 to 2gm specimen for testing.

2. Roll the test specimen between the palm or fingers on the ground glass plate to from a

thread of uniform diameter

3. Continue rolling the thread until it reaches a uniform diameter of 3.2 mm or 1/8 in.

4. When the thread becomes a diameter of 1/8 in. Reform it into a ball.5. Knead the soil for a few minutes to reduce its water content slightly.

6. Repeat steps 2 to 5 until the thread crumbles when it reaches a uniform diameter of 1/8 in.

7. When the soil reaches the point where it will crumble, and when the thread is a uniform

diameter of 1/8″, it is at its plastic limit, Determine the water content of the soil.

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Fig 16 Plastic Limit Set

Fig 17 Plastic Limit Roller

Note: Repeat this procedure three times to compute an average plastic limit for the sample.Calculation:

Trial

no.

No of

blow

Container

No

Container

weight

Weight of

Container

with soil

Weight of

Container

with dry soil

Moisture

content in

percent

1

2

3

21

15

12

1

2

3

19.5

18.85

18.81

50.84

53.76

47.80

43.68

45.66

40.92

29.6

30.2

31.17

From graph it is observed the moisture contain corresponding to 25 blows is 28.61approximately

Liquid Limit, LL:

Plot the relationship between the water content, w, and the corresponding number of drops, N, of the cup on a semi-logarithmic graph with water content as the ordinates and

arithmetical scale, and the number of drops on the abscissas on a logarithmic scale. Drawthe best fit straight line through the five or more plotted points. 12



Take the water content corresponding to the intersection of the line with the 25 dropabscissa as the liquid limit, LL, of the soil.

Plastic Limit, PL:

Compute the average of the water content obtained from the three plastic limit tests. The plastic limit, PL, is the average of the three water content.

Trial

no.

Container

No

Weight of

Container

with soil

Weight of

Container with

dry soil

Weight of

water

Weight of

dry soil

Moisture

content

1 4 20.56 20.22 0.39 1.21 28.09

Hence, Plastic Limit = 28.09 and Plasticity Index = liquid limit – plastic limit

Plasticity Index:

Calculation the plasticity index as follows:PI = LL-PL = 28.61 – 28.09 = 0.52

Where:LL = Liquid Limit, andPL = Plastic Limit.

Report:

1. Sample identification information2. Liquid Limit, Plastic Limit, and Plasticity Index to the nearest whole number.

Test Works in Civil Engineering

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