UNESCO-NIGERIA TECHNICAL & VOCATIONAL EDUCATION

REVITALISATION PROJECT-PHASE II

YEAR I- SE MESTER 2 PRACTICAL

Version 1: December 2008

NATIONAL DIPLOMA IN

CIVIL ENGINEERING TECHNOLOGY

SCIENCE AND PROPERTIES OF MATERIALS

COURSE CODE: CEC 104

TABLE OF CONTENTS WEEK 1: Grading tests on aggregates

Experiment 1: Sieve analysis of fine and coarse aggregates WEEK 2: Experiment 2: Determination of aggregate crushing value (ACV) WEEK 3: Experiment 3: Clay and silt content (Field setting test),

Moisture content and bulking of sand WEEK 4: Experiment 4: Determination of specific gravity of aggregates

Experiment 5: Determination of bulk density and voids of fine and coarse aggregates

WEEK 5: Experiment 6: Determination of setting time of cement

Experiment 7: Soundness test of cement WEEK 6: Experiment 8: Determination of specific gravity of cement

Experiment 9: Determination of fineness of cement WEEK 7: Experiment 10: Determination of compressive strength of cement WEEK 8: Experiment 11: Determination of compressive strength of cement WEEK 9: Site visit to any ongoing building construction WEEK 10: Testing of concrete cubes at 14 days

Experiment 12: Static modulus of elasticity of concrete

WEEK 11: Experiment 13: Consistency limits (Atterberg’s limit) WEEK 12: Experiment 14 WEEK 13: Experiment 15: Determination of aggregate impact value (AIV) WEEK 14: Experiment 16: Site visit to aggregate crushing plant WEEK 15: Site visit to deep excavation of soil

PROGRAMME: (ND) CIVIL ENGINEERING TECHNOLOGY

COURSE: Science and Properties of Materials

COURSE CODE: CEC104

COURSE SPECIFICATION : Practical Content

WEEK 1: GRADING TESTS ON AGGREGATES

EXPERIMENT 1: SIEVE ANALYSIS OF FINE AND COARSE AGG REGATES

Aim : To determine the sieve analysis on Fine and Coarse aggregates and their zones

Apparatus:

1. One set of B.S sieve of sizes 4.76, 2.40, 1.20, 600mm, 300mm, 150mm and

75mm.

2. One set of sieve sizes 38.1mm, 19.05mm, 9.52mm and 4.76mm.

3. A Balance readable and accurate to 0.1% of the weight of test sample.

Weighing Balance Set of Sieve

Theory:

Aggregate grading affects the strength of concrete mainly indirectly, through its

important effect on the w/c ratio required for a given workability. A badly graded

aggregate requires a higher w/c ratio and hence results in a weaker concrete.

Procedure:

1. For the fine aggregate, use a sample of approximately 1000gm and for the coarse

aggregate, approximately 3000gm.

2. Dry and clean all sieves and ensure that the samples are air dry.

3. Sieve the two samples in turn by shaking manually or mechanically.

Precaution: 1. Do not force the material through the sieves by hand pressure.

2. Lumps of fine material should be broken.

3. Only light brushing of the underside of the sieves should be done.

Results:

Complete a table as shown below for each material and hence plot grading curves on the

chart provided. By plotting also the zone limits according to B.S 882, determine the zone

for each aggregate.

Sieve size (mm)

Weight retained(g)

% retained % passing summation

Conclusion:

Comment on your results, grading, zone and compliance with standard specifications.

WEEK 2

EXPERIMENT 2: DETERMINATION OF AGGREGATE

CRUSHING VALUE (ACV). Aim: To determine, the aggregate crushing value of a sample of coarse aggregate. Apparatus: 1. A 152mm diameter, open ended steel cylinder with plunger and base plate.

2. A tamping rod of 9.5mm diameter and 609.6mm long.

3. A 3kg Balance.

4. A set of B.S test sieve of sizes: 12.7mm, 9.5mm and 2.0mm

5. A compression machine

Procedure: 1. Sieve the aggregate sample to pass through sieve size 12.7 mm and retained on

the B.S sieve 9.5mm.

2. Prepare sufficient aggregate for tests (about 5kg) and ensure that it is in a clean

and surface dry condition (according to standard requirement, it should be oven

dried, 100-110ºC).

3. Place the cylinder on the base plate and fill with aggregate in three equal layers

giving 25 blows to each layer.

4. Level off the top of the aggregate with the tamping rod and weigh (weight A).

Insert the plunger so that it just rests horizontally on the surface of the aggregate.

5. Test sample in the compression machine loading at 40KN/MIN to a load of

40KN(10 minutes)

6. Remove the material from the cylinder and sieve on a 2.40mm B.S test sieve.

7. Determine the weight of the fines passing the 2.40mm sieve (weight B) and

express this as a percentage of the total weight of the aggregate used as shown in

the calculation below.

8. Carry out two tests. Calculations: Aggregate crushing value = B⁄A x 100

Results: Report the mean of the two values to the nearest for impact test. Conclusion: Comment on your results and compare with the permissible values. WEEK 3

EXPERIMENT 3: CLAY AND SILT CONTENT (FIELD SETTING

TEST), MOISTURE CONTENT AND BULKING

OF SAND

Aim: To determine the percentage clay and silt content, percentage moisture content and

variation of the percentage of bulking with moisture content of sand.

Apparatus:

1. 250,500 and 1000ml measuring cylinders.

2. A siphon-can apparatus.

3. A 3kg balance.

4. Mixing trowel and glass plate.

5. A 1% solution of common salt in water.

6. A scoop and stirring rod.

Procedure:

a. Clay and Silt Content (Field Setting Test)

1. Place 50ml of the 1% salt solution in a 250ml measuring cylinder.

2. Add the sand gradually until the level of the top of the sand is at the 100ml mark.

3. Add more salt solution to bring the total volume of the mixture in the cylinder to

150ml and cover the cylinder.

4. Shake vigorously and repeatedly by turning it upside down and allow it to settle

for 3 hours.

5. Measure the thickness of the clay and silt layers and express as percentage of the

height of the sand below.

Theory:

The clay and silt will settle above the sand and the height of this layer (in mm) can be

expressed as a percentage of the height of the sand below (in mm). If the ratio exceeds

8%, test by more accurate method should be made (sedimentation in sodium oxalate

solution). Then the content of clay, silt and fine dust should not exceed

- 15% by weight in crushed stone sand.

- 3% by weight in natural and crushed sand.

- 1% by weight in coarse aggregate

b. Moisture Content of Sand (Siphon Can Test)

1. Close the upper and lower siphon and fill the can with water to above upper

siphon.

2. Open the upper siphon and discharge the water to waste. Open the lower siphon

and collect the water in a 500ml measuring cylinder, this is the calibration volume

(Vc).

3. Check whether the water is at the level of the lower siphons.

4. Add 2kg of the damp sand stirring to remove air.

5. Draw on scum on the surface to the side of the can, open the upper siphon and

collect the water in a measuring cylinder, volume (V).

Theory:

The total volume displaced by the damp sand is given by

Vb= V + Vc = Volume of sand + Volume of water on sand.

= M/S (l+r) + M.R/(l + r)

Where M = mass of sand = 2000g

S = specific gravity of the sand obtained in expt. 6

r = required moisture content by dry weight.

c. Bulking of Sand

1. Place 800g of the surface-dry sand in 1000ml measuring cylinder without

compacting and measure its volume, Vd.

2. Tip the sand unto a glass plate and add 4% of the water (32g) and mix thoroughly,

ensuring that none of the materials escape.

3. Replace the materials and measure the new volume, Vw

4. The percentage of bulking is given by

(Vw – Vd)100/ Vd

5. Repeat the procedure, adding additional increments of 32g of the water until the

sand is saturated i.e. it does not hold water.

Results:

Report the values of the clay and silt content, as well as moisture content and plot the

graph showing the variation of bulking with moisture content.

Conclusion:

Comment on the tests and your results showing the relationship between the three tests.

WEEK 4

EXPERIMENT 4: DETERMINATION OF SPECIFIC GRAVITY OF

AGGREGATES.

Aim: To determine the specific gravity of Fine and Coarse aggregates.

Apparatus:

1. A pycnometer

2. A balance of 3kg capacity

3. 11/2 liters gas jar and ground glass disc

4. A drying duster or soft absorbent cloth

Procedure:

a. Fine Aggregate

1. Fill the pycnometer with distilled water to full capacity with the screw cap

in position, dry the outside and weigh = p

2. Unscrew cap and introduce a sample of surface dry (oven dry) sand of

known weight, 500gm = B

3. Replace the cap and refill the pycnometer to full capacity with distilled

water and eliminate any trapped air by rotating the pycnometer on its side

whilst covering the hole with a finger. Dry the outside and reweigh with a

finger. Dry the outside and reweigh = Ps

4. Carry out two tests.

b. Coarse Aggregate

1. Use 1000gm sample = B

2. the procedure is similar to that of fine aggregate but using the gas jar and

ground glass disc in place of the pycnometer

3. Carry out two tests.

Calculations

Apparent Sp. Gs = B (P + B – Ps)

Results

Report the individual and mean results

Conclusion

Comment on your results and compare them with standard results.

EXPERIMENT 5: DETERMINATION OF BULK DENSITY AND

VOIDS OF FINE AND COARSE AGGREGATES

Aim: To determine the Bulk density and void ratio of fine and coarse aggregates

Apparatus:

1. Weighing balance of 5kg and 25kg capacity

2. Cylinders of 2.83 and 14.15 liters nominal capacity.

3. Scoop and drying duster.

Procedure:

1. The small cylinder is used for fine and the large one for coarse aggregate

2. Calibrate each cylinder to determine its actual volume.

3. Fill the appropriate dried cylinder overflowing with the surface – dry aggregate by

means of the scoop, the aggregates being discharged from a height of not more

than 5cm above the top of the cylinder.

4. Level the surface with a straight edge and determine the net weight of the

aggregate in the cylinder.

Calculation:

Bulk density = _Net wt. of aggregate_____ (kg/m3) Actual volume of Cylinder

Void ratio = 1 – Loose bulk density

Gs x 100

Results:

Report the loose bulk densities for the individual and mean result to the nearest kg/m3

and also report the void ratio.

Conclusion:

Comment on your results and the test.

WEEK 5 EXPERIMENT NO. 6: DETERMINATION OF SETTING TIME OF CEMENT Aim: To determine the standard consistence, initial and final setting time of a cement

sample.

Apparatus:

1. The vicat apparatus complete with mould, plunger, initial and final set needles;

2. Gauging trowel and

3. Weighing balance.

Vicat Apparatus and Accessories

Theory:

The purpose of this preliminary test is to determine the water/cement ratio required to

produce a cement paste of standard consistence. This often involves a process of trial and

error until the desired paste is achieved which will allow the vicat plunger to penetrate to

a point 5 to 7mm from the bottom of the vicat mould. Initial setting time is the time

elapsed since the mixing water was added to cement until the needle cannot penetrate

beyond 5mm from the bottom of the mould. The final setting time is the time elapsed

when the annular attachment (final set needle) cannot make an impression on the surface

of the cement paste. According to BS 4550 requirement, the initial setting time must not

Mould Tank

Automatic Vicat Apparatus

be less than 45 minutes and the final setting time must not be more than 10 hours for

normal cement.

Procedure:

A. Determination of Standard Consistency:

Mix carefully 400 grams of cement and add relevant quantity of water. Start with

a W/C ratio of 0.30 and vary this according to the penetration of the plunger. The

gauging time should be 5 minutes. Fill the mould lying on the steel plate in one

layer using the gauging trowel and smooth off the top of the paste and place the

mould under the plunger.

Lower the plunger onto the surface of the paste (i.e. from the 40mm mark),

release quickly and allow settling. The paste which will allow the plunger to sink

to within 5 to 7mm of the bottom of the mould is the standard consistence

required. If this is not achieved, change the W/C ratio properly and repeat the test

until the standard consistence is obtained. Record the W/C ratio for the standard

paste.

B. Initial Setting Time Test:

Prepare a second cement paste of standard consistence and place in the vicat

mould as described before. Lower the 1mm2 needle of the vicat apparatus gently

onto the surface of the paste, again, release quickly and allow it to sink to the

bottom of the mould. Repeat this every 10 minutes until the paste has stiffened

sufficiently for the needle to sink no further than 5 – 7mm from the bottom of the

mould (read this on the scale).

Record the initial setting time

C. Final Setting Time Test:

Replace the needle used in (b) above by a 1mm2 needle fitted with metal annular

attachment in vicat apparatus. Following the previous process, allow the annular

attachment to fall gently onto the surface of the test paste. Note the time for the

needle to make an impression on the surface of the paste but for the attachment to

fail to do so. This is the final setting time. Record it.

NOTE: Don’t discard the remaining paste yet. It can be used for Exp. No. 2

(soundness test) – ahead.

Result:

Report the W/C ratio of paste of standard consistence and also the initial and final setting

time.

Conclusion:

Comment on your results. Compare your results with the values specified by BS4550.

EXPERIMENT 7: SOUNDNESS TEST OF CEMENT

Aim: To determine the soundness of a cement sample by the “Le chatelier” method of

measuring its expansion

Apparatus:

1. The Le Chatelier method

2. Gauging trowel and glass plate.

3. Water container and water heater with thermostat (control).

Theory:

This test uses the expansion property of cement to determine its soundness. The

difference between the two measurements, D1 and D2 (described below) give the

expansion of the cement. According to BS 4550, this difference should not be more than

10mm for normal (or sound) cement.

Procedure:

Prepare a cement paste of the standard consistence. Place the Le Chatelier mould on the

glass plate and fill it with the paste keeping the slit of the mould gently closed by tying

with a piece of cotton whilst this operation is being performed. Cover the top of the

mould with another piece of glass and immediately immerse the whole specimen in clean

water, recording the temperature of the water before immersion. Prepare six (6) samples.

After 24 hours, remove mould and measure the distance between the pointers – (D1). Re

– submerge in water and boil in the water heater for 1 hour; the water to reach boiling

point in 25 – 30 minutes. Remove the mould from the water and cool in an air – tight

container. Finally, measure the difference between the pointers – (D2).

Result:

Report W/C ratio and difference between the two measurements. Reports the average of

the six samples

Conclusion:

Comment on the test and your result with respect to BS 4550 specification.

WEEK 6 EXPERIMENT 8: DETERMINATION OF SPECIFIC GRAVITY OF

CEMENT

Aim:

To determine the specific gravity of cement

Apparatus:

1. Specific gravity bottle

2. Weighing balance, oven and funnel

Materials:

Cement, kerosene and distilled water.

Procedure:

1. Weigh the empty S.G bottle = W1

2. Fill the bottle with distilled water and weigh

3. Empty the bottle and dry in oven at low temperature and allow to cool

4. Fill the bottle with kerosene and weigh = W3

5. Weigh small quantity of cement (say 20gm) = W5

6. Pour out some kerosene from the bottle and add this cement carefully to the bottle

using the funnel. Then fill the bottle to the brim with kerosene and weigh = W4.

7. Perform the two tests.

Result:

Tabulate your result like this

Test 1 Test 2

Weight of empty bottle (W1)

Weight of bottle + water (W2)

Weight of bottle + kerosene (W3)

Weight of cement (W5)

Weight of cement + Kerosene (W4)

Calculation:

Sp. Gr., S = W5 (W3 – W1)_________ (W5 – W3 – W4) (W2 – W1)

Conclusion:

Comment on the two results. Take the specific gravity of cement as 3.15

EXPERIMENT 9: DETERMINATION OF FINENESS OF CEMENT

Aim: To determine the fineness of cement

Apparatus:

1. Weighing balance

2. BS Sieve 170/90 microns.

Procedure:

1. Weigh 100g of cement and place in sieve BS 170/90 microns

2. Break with hands any lumps present in the weighed cement

3. Sieve it by gentle motion of the wrist for 15mins continuous.

Result: The residue when weighed should not exceed 10% by weight of the cement

sample

Conclusion:

Comment on the result.

WEEK 7 EXPERIMENT 10: DETERMINATION OF COMPRESSIVE

STRENGTH OF CEMENT Aim: To test the compressive strength of cement using cubes. Apparatus: 1. Cement mortar mixer or mixing tray and tools;

2. Standard vibrating machine;

3. 6 No. 70mm cube moulds;

4. An adequate quantity of standard sand

5. A weighing balance and thermometer

6. petroleum jelly and

7. Compression testing machine.

Theory:

Cement paste alone is not used for this test because of the unacceptably large variations

of strength thus obtained. Standard aggregates are used for making prescribed mortar or

concrete test mixes to eliminate effects from the measured strength of the cement.

Procedure:

A. Preparation of Test Specimen

Clean the moulds and oil with thin coat of mould oil. Apply a thin film of

petroleum jelly to the joints of the two halves of the moulds and also to the

contact surfaces of the bottom of the mould and its base plate in order to ensure

that no water escapes during the vibration. The mix proportion to be used is 1:3

(one part by weight of cement to three parts by weight of the standard sand) with

a W/C ratio of 0.4. Weigh the quantities of material for the 6 cubes as follows:

cement, 1110gm; standard sand, 3330gm; water, 444gm.

B. Mixing

Mix dry the cement and sand mixture in a mortar or on a mixer or a mixing tray

with a trowel for one minute and then with water for a further 4 minutes,

producing a cement mortar of homogenous consistency. Ensure that none of the

materials are allowed to escape during mixing.

C. Compaction

Place the assembled mould on the vibrating machine secures it into position and

fills with prepared cement mortar, using a suitable hopper to facilitate filling.

Vibrate the mould at 1200 + 400 vibrations/minute for two minutes. Prepare 6

similar moulds.

D. Curing

Cover each cube with an impervious sheet immediately after vibration for 24

hours to cure at room temperature. Record the room temperature and relative

humidity. After 24 hours, remove the cubes from their moulds, mark them for

identification (i.e. date of cast and group No.) and immerse in clean water until

just prior for testing. Record the temperature of the water.

E. Testing

Test three of the prepared cubes at 3 days and the remaining three at 7 days. The

rate of loading of the compression testing machine should be 34.475N/mm2/min.

Minimum permissible compressive strength is 23N/mm2 for 3 days.

Results:

Report the mean compressive strength in N/mm2 at 3 and 7 days to the nearest 0.5N/mm2

Conclusion:

Compare your results with BS 4550 requirements i.e. 13N/mm2 and 23N/mm2 for

concrete and mortar cubes at 3 days respectively.

WEEK 8 EXPERIMENT 11: DETERMINATION OF COMPRESSIVE

STRENGTH OF CEMENT

Aim: To test the compressive strength of cement using concrete cubes

Apparatus:

1. 12 Nos. 150mm cube moulds

2. 1 cylindrical shape of mould to cast concrete cube

3. Vibrating machine or tamping rod

4. Concrete mixer or mixing tray

5. Thermometer and petroleum jelly

6. Compression Testing machine

7. Curing Tank

ADR-Auto 250/25 Compression Machine 250/25 kN capacity

EL39-5600 Compression Frame Jig Assembly with Accessories

Reversible Concrete Mixer

Materials:

1. Coarse – aggregate, crushed rock, 19.05mm max. size.

2. Fine aggregate, River sand, cement sample to be tested.

3. Mixing water, weighing, mixing and curing facilities.

Concrete Moulds

Procedures:

a. Preparations of Specimen

Use 1.6 mix proportions (cement/Aggregate ratio) by weight and 0.6 W/C ratio

based on 6kg of cement for the 6 cubes. Determine sand; 19.05mm Aggregate

proportion and the weight of materials required and measure them.

b. Mixing:

Mix the cement and aggregates dry in a mechanical mixer or mixing tray with a

trowel for one minute until the mixture is uniform. Add the water and mix

thoroughly for three minutes.

C. Compaction:

Fill the concrete into the moulds in two approximately equal layers and vibrate

mechanically or tamp each layer for at least 25 strokes uniformly distributed over

the mould. Trowel the sides of the cubes carefully and smooth off the top.

D. Curing:

Cover the top of the cubes with polythene sheets and place damp sacks over them

for 24hours. De-mould the cubes and mark their tops for identification. Weigh the

cubes; immerse the cubes in clean water in the curing tank until ready for testing.

Record the temperature of the water.

E. Testing:

Remove the cubes, wipe out and weigh. Test 3 cubes at the ages of 3 and 7 days

each. Determine and record the crushing loads on the compression Testing

machine.

Calculation:

Compressive Strength = Crushing load __ (N/mm2) Area of specimen

Density = __weight of specimen___ (kg/m3) Volume of the Specimen

Result:

Report the weights of the materials used the room and curing tank temperature, the

weight and density of the cubes, the crushing load and strength of the cubes.

Conclusion

Comment on the workability of the mix and the test results. Report the mean compressive

strength in N/mm2 at 3 and 7 days to the nearest 0.35N/mm2 and compare with B.S 4550

requirements.

WEEK 9

SITE VISIT TO ANY ONGOING BUILDING CONSTRUCTION

Aim: To see the casting of concrete beams, columns and floor slabs

Outcome of students visit to the site: Write report describing what you have seen and

comment on the quality of these structural members. A typical report would be five pages

of writing plus diagrams.

WEEK 10 TESTING OF CONCRETE CUBES AT 14 DAYS

Remove the cubes, wipe out and weigh. Test 3 cubes at the ages of 14 days.

Determine and record the crushing loads on the compression Testing Machine.

Calculation: Compressive Strength = Crushing load __ (N/mm2) Area of specimen

Density = __weight of specimen___ (kg/m3) Volume of the Specimen

Result:

Report the weights of the materials used, the room and curing tank temperature, the

weight and density of the cubes, the crushing load and strength of the cubes.

Conclusion:

Report the mean compressive strength in N/mm2 at 14 days and compare with B.S

4550 requirements.

EXPERIMENT 12: STATIC MODULUS OF ELASTICITY OF CONC RETE

Aim: To determine the static (secant) modulus of elasticity of hardened concrete

Apparatus:

1. The concrete cylinders prepared in week 8 experiment 10

2. Mechanical Extensometer

3. Compression Testing Machine.

Theory:

When a stress is applied to the concrete, the observed strain is made up of two parts: the

elastic strain and the creep. Therefore, the secant modulus determined from laboratory

tests depends on the rate of application of the load. Thus, BS 1881 specifies a rate of

loading of 15N/mm2/min., and the secant modulus shall be that cube strength plus

1N/mm2.

Procedure:

1. Place the extensometer centrally over the concrete cylinder and tighten the screw

and remove the two spacer bars.

2. Fit the two dial gauge in the tapped holes in the upper ring and adjust them to

zero. Place the cylinder in the compression test machine and centralize it on the

platen.

3. Load the specimen at a rate 15N/mm2 for four stresses representing 15, 25, 33 and

50% of the ultimate cube strength, taking dial gauge reading at the loading

increment with a little delay as possible.

4. Maintain the maximum load for three minutes and take another dial gauge

reading. Reduce the load to zero taking the dial gauge readings at the same

percentage of ultimate cube strength.

Note: The dial gauge readings are divided by 2 to obtain the average deformation on

both sides of the cylinder.

Result:

Plot the stress – strain curve for loading and unloading. Determine the initial tangent

modulus at a stress of 33% of the strength. Report all the obtained results in this format.

Dial Gauge Reading Strains

Load (KN)

Stress (N/mm2)

Loading (mm)

Unloading (mm)

Loading (mm)

Unloading (mm)

Conclusion:

Comment on the test and your result e.g. the initial tangent modulus and secant tangent

modulus and evaluate their compliance with standard values.

WEEK 11 EXPERIMENT 13: CONSISTENCY LIMITS (ATTERBERG’S

LIMIT) As moisture is removed from a fine-grained soil it passes through a series of state i.e.

plastic, semi-solid and liquid. The moisture contents of soil at the points where it passes

from one stage to the next are known as consistency limits.

a. Liquid limit (L.L)

Aim: The minimum moisture content at which the soil will flow under its own weight.

Apparatus: 1. Liquid limit device and grooving tools. 2. Distilled water 3. Balanced water 4. Drying oven 5. Desiccators 6. Evaporating dish 7. Watch glasses drying can 8. Spatula.

Weighing Balance Casagrande Apparatus

Drying Oven

Procedure: 1. The limits should be determined on what portion of the soil finer than a No. 40

sieves or a N0. 36 sieve.

2. Take above 100gms of moist soil and mix it thoroughly with distilled water to form

a uniform paste.

3. Place a portion of the paste in the cup of the liquid limit depth smooth the surface

off to maximum depth of (12.5mm) and draw the grooving tool through the same

sample along the symmetric axis of the cup, holding the tool perpendicular to the

cup at the point of contact.

4. Turn the crank at a rate of about two revolutions per second and count the blows

necessary to close the groove in the soil on a distance of (12.5mm). The groove

should be closed by a flow of the soil and not by slippage between the soil and the

cup.

5. Take approximately 10gms of soil near the closed groove for a water content

determination.

6. By altering the water content of the soil and repeating steps 2 to 5, obtain four water

content determinations in the range of ten to forty blows.

Plot a logarithm graph of water content (%) against the number of blows

Calculation/ conclusion

Read from the graph, the LL No. from the 25No.’s of blows against the corresponding

moisture content (%)

a. Plastic Limits (PL)

Aim: The minimum moisture content at which the soil can be rolled into a thread of

3mm diameter without breaking up.

Apparatus:

Same as in liquid limit test

Procedure:

1. Mix thoroughly about 15ms of the moist soil

2. Roll the soil on a glass plate with the hand until it is in diameter

3. Repeat the step 2 until 3mm diameter thread shows sign of crumbling

4. Take some of the crumbling material obtained in step 3 for a water content

determination

5. Repeat steps 2-4 to obtain three determinations which can be averaged to give the

plastic limit.

Conclusion:

The result from the average plastic limits from the oven then.

b. PLASTICITY INDEX

Aim: This is a range of moisture content over which a soil is plastic

Procedure: The liquid limit and the plastic limit shall be determined by the procedure

indicated in the previous notes.

Calculation/conclusion:

The plasticity index (PI) shall be calculated from the formula:

PI = LL – PL

SHRINKAGE LIMIT :

Aim: The maximum moisture content at which further loss of moisture does not cause a

decrease in the volume of the soil.

Apparatus:

a. Same as in the liquid limit test

b. Shrinkage limit cone/ mould

Shrinkage limit cone/mould

Procedure:

1. The mould should be thoroughly cleaned and a thin film of silicon grease should

the be applied to its inner walls to prevent the soil from adhering to the mould

2. A soil sample weighing about 150gms shall then be taken from the material

passing sieve No.36 (420 minutes).

The sample shall be placed on the flat glass plate and thoroughly placed mixed

with distilled water, using palette knives: until the mass becomes a smooth

homogeneous paste, with moisture content approximately the liquid limit of the

soil.

3. Soil- mixer mixture shall be placed in the mould; the mould shall be slightly

jarred to remove any air pockets in the mixture. The soil shall be leveled off

along the top of the mould with palette knife; all soil altering to the run of the

mould shall be removed by wiping with a damp cloth.

4. The mould shall be placed in an oven for 24 hours at a temperature range of

1050- 1º C to complete drying.

5. The mould and soil shall then be cooled and the mean length of the soil bar

measured. If the specimen had become curved during drying, it shall be

carefully removed from the mould and the top and bottom surfaces measured.

The mean of these two lengths shall be taken as the length of the oven- dried

specimen.

Calculation/ conclusion:

The shrinkage limit of the soil shall be calculated as a percentage of the original length of

the specimen using the formula;

S.L = 1- (length of oven dry sample) x 100

(Initial length of specimen)

WEEK 12

EXPERIMENT 14 a. Testing of concrete cube at 28 days Testing: Remove the cubes, wipe out and weigh. Test the last three cubes at age of 28 days.

Determine and record the crushing loads on the compression testing machine. Calculation: Compression strength = Crushing load (N/ mm²) Area of specimen Density = Weight of Specimen (Kg/ m³) Volume of the Specimen Result: Report the weights of the materials used the room and curing tank temperatures, the

weight and density of the cubes, the crushing load and strength of the cubes.

Conclusion: Report the mean compressive strength in N/mm² and compare with B.S 4550

requirements.

b. Water absorbtion/ compressive strength of brick Water absorbtion: Aim: To determine the percentage of water absorption in brick. Apparatus: 1. Washing balance 2. Curing tank 3. Compression testing machine 4. Drying oven 5. A piece of cloth

Procedure: 1. Weigh the brick 2. Immerse brick in water for 24 hours 3. Remove sample from water and clean surface with dry cloth and record the weight as

‘A’ 4. Oven dry brick for 30 minutes and weigh it as ‘B’ Calculation: Percentage of absorption = A – B x 100 B Result:

Report the percentage of absorption.

Conclusion:

Comment on your result by comparing with the standard values.

CRUSHING OF BRICK Aim: To determine the compressive strength of brick after immersion and oven dry. Apparatus:

1. Compressive testing machine.

Testing: Determine and record the crushing loads on the compression testing machine. Result: Report the compressive strength. Conclusion:

Comment on your result by comparing with standard and requirement.

WEEK 13 EXPERIMENT 15: DETERMINATION OF AGGREGATE IMPACT

VALUE (AIV) Aim: To determine the impact of a sample of Coarse Aggregate Apparatus: 1. An Aggregate impact testing machine complete with standard cylindrical measure of

76.2mm diameter and 50.8mm high and tamping rod of 9.5mm diameter and

228.6mm long.

2. A set of B.S. test sieves of sizes: 12.7mm, 9.52mm and 2.40mm.

3. A 3kg balance.

Theory:

The impact value is expressed as percentage of fines passing the 2.40mm sieve (to the

nearest whole number) to total weight of sample. The permissible AIV is 45% for

ordinary concrete used for wearing surfaces.

Procedure: 1. Prepare a sample of the coarse aggregate which passes the 12.7mm sieve and is

retained on the 9.52mm sieve.

2. Prepare sufficient aggregate for two tests and ensure that it is in a clean and surface

dry condition.

3. Fill the 7.6mm diameter cylinder in three equal layers giving 25 strokes of the 22.9cm

metal tamping rod to each layer.

4. Level off the top of the aggregate to the nearest gram and use the same weight of

material for each test = weight A.

5. Place the whole of the sample in the cup, fix firmly in position on the base of the

impact machine, and apply 25 blows of the tamping rod.

6. Subject the sample to 15 blows by applying the hammer to fall freely.

7. Sieve the crushed aggregate on a 2.40mm sieve and determine the percentage passing

by weight = weight B

8. Carry out two tests.

Calculation: Aggregate Impact Value (AIV) = B x 100 A Result:

Report the mean of the two tests.

Conclusion:

Comment on your results by comparing them with the standard values.

WEEK 14 EXPERIMENT 16: SITE VISIT TO AGGREGATE CRUSHING PL ANT Aim: To understand the production of aggregates, see the equipments and materials

produced.

Outcome: Write report describing what you have seen and also comment on quality of

aggregates. A typical report will be four pages of writing plus diagrams.

WEEK 15 SITE VISIT TO DEEP EXCAVATION OF SOIL Aim: To see soil profile, identification of soil colours, touch and soil types.

Outcome: Students are to report on what they have observed and identified on the field.

A typical report of five pages, diagrams inclusive.