Determine Silt Content of Sand

Experiment 1
Normal Consistency of Hydraulic cement
Theory
The correct amount of water needed should be determined exactly and correctly because many
properties of mortar such as rate of hydration, setting time, strength, workability depends on the
specific water cement ratio.
Cement is a finely ground powder of chemically combined argillaceous materials and calcareous
materials with iron oxide, gypsum and small amount of other ingredients. Cement, when mixed
with water it sets and hardens into a solid mass upon hydration. The normal consistency of
hydraulic cement refers to the amount of water required to make a neat paste of satisfactory
workability.
Apparatus
1. Weight and weighing devices.
2. Glass graduates (200 or 250) ml capacity.
3. Vicat apparatus with the plunger end, 10 mm in diameter.
4. Trowel and containers.
5. Mixing glass plate 30cm x 30cm

Procedure
1. Place the dry paddle and the dry bowl in the mixing position
in the mixer.
2. Place all the mixing water in the bowl.
3. Add the cement to the water and allow 30 s for a absorption
of the water.
4. Start the mixer at low speed for 30 s
5. Stop for (15 s) and make sure no materials have collected
on the sides of the bowel.
6. Start mixing at medium speed for (1 min).
7. Quickly form the cement paste into the approximate shape of
a ball with gloved hands.
8. Putting hand at (15cm) distance, throw the cement paste ball
from hand to hand six times.
9. Press the ball into the larger end of the conical ring,
completely fill the ring with paste.
10. Remove the excess at the larger end by a single movement
of the palm of the hand. Place the ring on its larger end on
the base of the plate of Vicat apparatus.
11. Slice off the excess paste at the smaller end at the top of
the ring by a single sharp- ended trowel and smooth the top.
(Take care not to compress the paste).
12. Center the paste under the plunger end which shall be
brought in contact with the surface of the paste, and tighten
the set-screw.
13. Set the movable indicator to the upper zero mark of the
scale or take an initial reading, and release the rod
immediately. This must not exceed 30 seconds after
completion of mixing.

14. The paste shall be of normal consistency when the rod
settles to a point10±1mm below the original surface in 30
seconds after being released.
15. Make trial paste with varying percentages of water until the normal consistency is
obtained make each trial with fresh cement.
Calculation
The percentage of water can be calculated from the following formula
(%) water = X 100
Trial 1
Weight of water (W wt) = M wt x g; M wt=V wt x g wt
V wt=84ml=84 x 10-6
m3, P wt=1000kg/m3, M wt=84 x 10-6
m3 x (1000kg/m3), M wt=84 x 10-3
kg
Wwt= 84 x 10-3
kg x 9.81m/sec
W ce= (0.3kg) x 9.81m/sec2
W wt/W ce = (84 x 10-3
kg/9.81m/s) / (0.3 x 9.81) N
W wt/W ce = 0.28
(%) water = X 100 = 28 %
Penetration depth (mm) = 4.5
Trial 2
Weight of water (W wt) =M wt x g; M wt=V wt x g wt

Vwt= 96ml=96 x 10-6
m3, g wt=1000kg/m3
, g wt=1000kg/m3
, M wt= (96 x 10-6
m3
) x (1000)
kg/m3
,
M wt=96 x 10-3
kg
Wwt = (96 x 10-3
x 9.81) N ; W ce= (0.3kg) x 9.81m/sec2
= 2.943
Wwt /Wce = 96 x 10-3 x 9.81/ (0.3 x 9.81) N=0.32
(%) water = X 100 = 32 %
Penetration depth (mm) = 13.5
Conclusion
Though the percentage of water lies on the standard range it is not normal consistent because the
percentage depth doesn’t lie between 10±1.
Experiment 2
Initial and final time of Setting of Hydraulic Cement
Objective
To determine the initial setting time and final setting time of a cement paste having normal consistency.
Theory
Up on hydration, cement forms a solid and hard mass when mixed with water which is known as setting
of cement and the time it takes is known to be the setting time. This time is affected by the amount of

water used to prepare cement paste; i.e. which is the water cement ratio. Cement pastes with different
water cement ratios will generally have different setting times.
Generally there are two types of setting times to be determined in the laboratory, initial and final setting
times. The duration of cement paste related to 25mm penetration of the vicat needle in to the paste in 30
seconds after it is released is called the initial setting time, while the final setting time is that related to
zero penetration of the vicat needle in to the paste. According to the Ethiopian standards the initial setting
time for cement should not be less than 45 minutes and the final setting time should not exceed 10hrs.
Apparatus
 Vicat Apparatus with the needle end, 1mm in diameter.
 Weights and weighing devices
 Graduated Cylinder (200 or 250) ml capacity
 Mixing Dish
 A Trowel and containers.
Procedure
1. Weigh (300) gm cement.
2. Prepare amount of water as to that calculated in normal consistency test.
3. Prepare a cement paste following same steps mentioned in the previous test (ExpNo. 1).
4. Allow the time of setting specimen to remain in the moist cabinet for 30 minutes after molding
without being disturbed. Determine the Penetration of the 1mm needle at this time and every (15)
minutes until a penetration of 25mm or less is obtained.
5. To read the penetration, lower the needle of Vicat Apparatus until it touches the surface of the
cement paste. Tighten the screw and take an initial reading. Release the set screw and allow the
needle to settle for 30 seconds, and then take the reading to determine the penetration.
6. Note that no penetration shall be made closer than (6mm) from any previous penetration and no
penetration shall be made closer than (9.5mm) from the inside of the mold. Record the results of

all penetration, then by drawing a curve determine the time when a penetration of 25 mm is
obtained. This is the initial setting time.
7. The final setting time is when the needle dose not sinks visible into the paste.
8. Draw a graph for (penetration - time). Show the time which gives penetration of (25 mm) this
will be the initial setting time.
Note: According to ASTM C150:
Initial time of setting should not be less than 45 min.
Final time of setting should not be more than 375 min.
Calculation
Observed Data
Elapsed Time
(min)
Penetration
depth ( mm)
15 40
30 40
45 39
60 38
75 37
90 33
105 28
120 29
135 26
150 24
345 11
360 10
375 10
390 8
405 7
420 3
435 3
450 2
465 0
480 0
The initial setting time = 120 minutes

The final setting time = 300 minutes
Conclusion
According to the Ethiopian standards the recommended initial setting time is a value which is not less
than 45 minutes and shouldn’t exceed 10 hours for the final setting time. Therefore in the case of our
laboratory conduct both the initial and final setting times are fulfilled according to our country’s standard.
Experiment 4
Silt Content of Sand
Objective
The main objective is to determine the content or presence of silt with in the sand.
Theory
Sand is a product of natural or artificial disintegration of rocks and minerals. Sand is obtained from
glacial, river, lake, marine, residual and windblown deposits. Sand which is used for making of mortar
should be well graded. The particles should not be all fine or coarse. Deposits of sand contain other
materials such as dust, loam and clay that are finer than sand. The presence of such materials to be bound
together and hence the strength of the mixture. The finer particles do not only decrease the strength but
also the quality of the mixture produced resulting in fast deterioration. Therefore it is very necessary to
make a test on the silt content before using the sand for the intended purpose.
Apparatus
 Clean water ( tap water)
 Funnel
 Sample sand
 Small size spoon
 Dish for taking sample of sand

 Graduated cylinder
 Scoop
Procedure
1. Take graduated cylinder or jar having a capacity of greater than 100ml
2. Pour 30ml of sand to the cylinder
3. Fill Water approximately ¾ of cylinder
4. Shake the cylinder
5. Leave the cylinder for about an hour.
6. Measure the amount of fines
Calculation
% of silt content in given sand can be calculated using the following formula
Silt Content (%) =
𝑨𝒎𝒐𝒖𝒏𝒕 (𝑨)𝒐𝒇 𝒔𝒊𝒍𝒕 𝒅𝒆𝒑𝒐𝒔𝒊𝒕𝒆𝒅 𝒂𝒃𝒐𝒗𝒆 𝒕𝒉𝒆 𝒔𝒂𝒏𝒅
𝑨𝒎𝒐𝒖𝒏𝒕 𝒐𝒇 𝒄𝒍𝒆𝒂𝒏 𝒔𝒂𝒏𝒅 (𝑩)
X 100
Since we did not get the collected data of our lab activity, we have assumed the values of A and B to be:
A=2 B=24
Silt Content (%) =
𝟐
𝟐𝟒
X 100 = 8.333 %
.

Conclusion
According to the Ethiopian standard, if the % of silt content of the sand is greater than 6% it shall not be
used for construction.
Therefore, in the above laboratory experiment the % of silt content is 8.333% and it is not suitable for
construction purpose since it is greater than the standard value. Therefore the sand should be washed or
sieved to decrease its silt content.
Experiment 5
Workability of Mortar
Objective
To determine the workability of fluidity of fresh mixed mortar.
Theory
Mortar is a mixture of cement, sand and water. It is used to make a strong firm joint in bricks, blocks or
masonry units. In structural walls (those that carry loads in addition to their own weight), the mortar has
to be as strong as the units laid in order to transfer from the upper to the lower units. In nonstructural
walls also the mortar should be strong enough to carry the weight of the mass above it.
The composition of mortar can be varied in relation to its end use. Mortars of different quality can be
produced by varying the proportion or types of the constituents. For example, mortar produced from sand
of circular grains results in better workability than those produced from sand of angular grains. On the
other hand sands of angular grains give better strength.

Apparatus
 Mixing dish
 Trowel
 Flow table apparatus and flow mold
 Molds
 Balance
 Graduated cylinder
Procedure
1. Prepare cement sand and water with given proportion .
2. Mix cement and sand for about a minute(dry mix) then add the required amount of water and mix
for about two minutes.
3. carefully wipe the flow table top clean and dry then place the flow mold at the center of the table.
4. Fill the mortar to the mold with three layers and tamp 25 times each layer with a tamping rod.
5. Cut off the mortar to a plane surface.
6. Wipe the table top clean and dry being especially careful to remove any water from around the
edge of the flow mold.
7. Lift the mold away from the mortar and then drop and then drop the table 25 times within 15 sec.
through a height of 13 mm

8. Using the caliper determine the flow by measuring the diameter of the mortar along the lines on
the tabletop (take four readings)
According to ASTM standards, the mortar is said to be workable if the sum of the four diameters
is between 95 and 100.
Calculation
In order to find the workability measure of the concrete we will just calculate the average of the four
readings assumed since we are not given the results of our experiment:
AA’ = 15 BB’ = 15.6 CC = 15.73 DD’ = 15. 85
When they are summed up the result is 62.18.
By taking the average of the above readings workability of concrete = 62.18 / 4 = 15.545

Conclusion
According to ASTM standards, the mortar is said to be workable if the sum of the four diameters is
between 95 and 100 or 15.2 – 16 inches. And in our case the averages of the four readings is 15.545.
Here from our assumed data we have observed the sum of the four diameters to be 62.18. therefore our
concrete have got poor workability that it is not between 95 and 100 ELE which are the standards.
Experiment 6
Sieve Analysis
Objective
To determine the particle size distribution of a course and fine aggregates and also to determine the fines
modulus and to classify the aggregates as well graded and poorly graded.
Theory
It is very useful to know the physical and chemical characteristics of aggregates since they contain almost
65 to 75 percent of the total volume of concrete. In order to calculate the proportions of the materials used
and produce concrete of desired properties we need to know the characters of the aggregates and also its
grading system.
Apparatus
 Series of standard sieves
 Riffle box
 Electronic balance
 Sieve shaker
 Shovel
 Sieve brush

Procedure
Procedure for grading coarse aggregates
1. The first step was to weigh a 20 kg sample of coarse aggregates
2. Second a representative sample was quartered
3. The third step was that a sample of 2KG was taken from the quartered
4. Then empty sieves were weighed and the data was recorded.
5. Here the 2 KG sample was placed on the top sieve (the one having larger opening size).
6. Here after the sample was shook for about 2 minutes in a sieve shaker.
7. Finally the weight retained on each sieved was calculated.
Procedure for grading fine aggregates
1. The first step was to weigh a 2KG of a sample of fine aggregates
2. Second the sample was quartered using a riffle box.
3. The third step was to take a 500 gm from the quartered sample.
4. Then the pan was placed to the bottom of the sieve shaker and the other sieves were put
in to the pan with increasing opening sizes of the sieves.
5. In this step the 500 gm sample was placed on the top of sieve
6. Then the sample was shook for about 2 minutes in a sieve shaker
7. Doing the above, we weighed each sieve together with the aggregate retained on it.
8. Finally the weight retained on each sieve was calculated.

Calculation
For fine aggregates we can plot all the data in the following table
Sieve
(mm)
Weight
of
sieve
Weigh
t of
sieve
and
sand
Amount
Of
retained
Wt.
Retained
(%)
%
Cumuli.
Retained
%
Passing
9.5 454.6 454.6 0 0 0 100
4.75 566.6 567.3 0.7 0.14 0.14 99.86
2.36 396.6 420.5 23.9 4.85 4.99 95.01
1.18 372.4 457.3 84.9 17.24 22.23 77.77
0.6 312.5 523.4 210.9 42.82 65.06 34.94
0.3 308.9 444.3 135.4 27.49 92.55 7.45
0.15 277.8 310.2 32.4 6.58 99.13 0.87
Pan 416.5 420,8 4.3 0.87 100 0
sum 492.5 100 284
FM = (0.14+4.85+17.24+42.82+27.49+6.58+0.87)/100 =2.84
The following table is the Ethiopian standard for fine aggregates
Sieve Size (mm) Percentage Passing
9.5 100
4.75 95 – 100
2.36 80 – 100
1.18 50 – 85
0.6 25 – 60
0.3 10 – 30
1.15 2 – 10

Conclusion
The fineness modulus of our experiment is 3.25. And the calculated percentage passing of the experiment
carried on sieve analysis satisfies the Ethiopian Standard.
Experiment 7
Workability test of concrete (slump test)
Objective
The main objective of this test is to determine the workability of concrete in different
construction area.
Theory
A concrete mix, which is either produced at a ready mix plant or on site, must be made of the right
amount of cement, aggregates and water to make the concrete workable enough for easy compaction and
strong enough for good performance in resisting stresses after hardening. If the mix is too dry, then its
compaction will be too difficult and it is too wet, then the concrete is likely to be weak.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.1 1 10
Percent
Passing
By
Weight
(%)
Sieve Size (mm)
Gradation Curve
Lower Limit
Upper Limit
Passing(%)

During mixing the mix might vary without the change very noticeable at first. For instance, a load of
aggregate may be wet or drier than what we expected these due to variations in the amount of water added
to the mix. These all necessitate a check on the workability and strength of concrete after producing.
Slump test
Slump is a measurement of concrete's workability or fluidity. It's an indirect measurement of concrete
consistency or stiffness. A slump test is a method used to determine the consistency of concrete. The
consistency or stiffness indicates how much water has been used in the mix.
In the slump test the distance that a cone full of concrete slumps down is measured when the cone is lifted
from around the concrete. The slump can vary from nil on dry mixes to complete collapse on very wt
ones. One drawback with this test is that it is not helpful for very dry mixes.
There are three types of slump
1. True Slump: where the concrete just subside, keeping its shape approximately
2. Shear Slump: where the top half of the cone shears off and slips sideways down an inclined plane.
3. Collapse Slump: where the concrete collapses completely.
Apparatus
 Standard Slump cone 300 mm high with a bottom D. of 200 mm and top
D. of 100mm
 Scale for measurement(tape)
 Tamping rod (steel) 16mm diameter, 600mm long, with one end rounded

Procedures
1. The first step was cleaning up the cone
2. Second, someone stand with feet on the foot rests.
3. Thirdly, the cone was filled with concrete up to one third of its height and the layer was rod
concrete exactly 25 times using the tamping rod.
4. Two further layers of equal height were added, then it was rode in each one in turn exactly
25 times, and the rod was allowed to penetrate through in to the layer below. After Roding
the top layer it was kept sure that there was a slight discharge of concrete.
5. Then the concrete was strike off using steel float
6. The cone was wiped and the base plate was kept clean by keeping someone’s feet still on the
foot rests.
7. Very carefully the cone was lifted straight up, was turned over and was put down on the base
plate next to the mound of concrete. As soon as the cone was lifted the concrete was slump
to some extent.
8. Finally using the tape it was measured from the underside of the rod to the highest point of
the concrete to the nearest slump end.
Standard Data
Slump (mm) Degree of Workability
0 – 25 Very Low

25 – 50 Low
50 – 100 Medium
100 – 175 High
> 175 Collapse
Conclusion
 In our laboratory conduct we found slump 30mm. so our concrete degree of workability
is low
 We observed that the slump of the concrete was a true slump
EXPERIMENT 8
REBOUND HAMMER TEST
Objective
hammer.

index. The compressive strength can be read directly from the graph provided on the body of the hammer.
Procedure
1. Before commencement of a test, the rebound hammer should be tested against the test
anvil, to get reliable results, for which the manufacturer of the rebound hammer indicates
the range of readings on the anvil suitable for different types of rebound hammer.
2. Apply light pressure on the plunger – it will release it from the locked position and allow
it to extend to the ready position for the test.
3. Press the plunger against the surface of the concrete, keeping the instrument
perpendicular to the test surface. Apply a gradual increase in pressure until the hammer
impacts. (Do not touch the button while depressing the plunger. Press the button after
impact, in case it is not convenient to note the rebound reading in that position.)
4. Take the average of about 15 reading

Conclusion
The rebound hammer test is a modernized instrument that measures the strength of a concrete without
destructing it. Hence it a method of choice for easy, quality and fast measurements.
Experiment 9
Compressive strength of Concrete
Objective
 knowing compressive-strength of concrete
 by testing concrete-cube
Theory

Compressive strength
The compressive strength of a material is defined as the resistance to failure under the action of a
compressive force. For concrete compressive strength is an important parameter to determine the
performance of the concrete during service condition. The major objective of concrete structures
is carrying loads coming to them. These loads may be of dead, live, earthquake, wind or snow
types or their combinations. The concrete produced, therefore, must not fail under the actions of
any of such loads. The commonest work for hardened concrete involves taking a sample of fresh
concrete and putting into special cube molds so that, when hard, the cubes can be tested to failure
in a special machine in order to measure the strength of the concrete. The results obtained from
compression test on hardened concrete cubes are used to check that its strength is above the
minimum specified and to assess the control exercised over the production of concrete
Factors Affecting Compressive Strength
 Stress Distribution in Specimens.
 Effect of L/d ratio.
 Specimen Geometry.
 Rate of Loading.
 Moisture Content.
 Temperature at Testing.
Apparatus:
 Cube Mould (150x150x150 mm )
 Tamping bar (16 mm diameter )
 Spatula vibrator,
 Steel Float/Trowel
 Mixer
Procedure
1. The first step was to use the same concrete mix for which workability was determined.
2. Second cubical molds (15x15x15) cm3 were prepared and oiled in order to easily molding of
the concrete cubes.
3. Then concrete was filled in the cubical mold and vibrated in order to remove air bubbles for
about 30 seconds.

4. At this stage the surface was smoothened and the excess concrete on the cube molds were
removed by using spatula and also the mixing dates at the top of the concrete were recorded.
5. Here the concrete was removed after 24 hours from the mold and was cured in water for 7
days.
6. Then the concrete specimens were load to failure at 3, 7 and 28 days of age by using testing
machine and the failure loads were recorded in each case.
7. Finally the stresses at failure were calculated.
Calculation
The compressive strength can be calculated from the following formulas:
Compressive Strength (Mpa) = failure load (KN)/contact area (m2)
Test age
(days)
Dimensions (cm) Area “A”
(cm2 )
Volume
(cm3
)
Failure Load
“F” (KN)
Strength
(Mpa)(F/A)
L W H
7 15 15 15 225 3375 874.6 388.71

Conclusion
Compressive strength of the concrete is 38.87 from the test we done.
To have more accurate result we need to add other test and we use the mean of the compressive
strength to represent compressive strength of the concrete.

Experiment 10
Testing of reinforcing steel
Objective
The main objective is to determine yield strength, tensile strength or a reinforcement bar and to draw
stress strain diagram.
Theory
Steel is mainly composed of iron, but the iron is alloyed, or associated with, various other materials. It is
up on the nature and relative amounts of these special ingredients that the physical properties of steel
depend. For instance, introducing the metal chromium results in a pronounced resistance to rusting among
other useful properties and is given the name stainless steel. The element manganese, on the other hand,
gives good wearing properties to steel, making it suitable for use in the manufacture of rains. There are,
therefore, various types of steels, known respectively as chromium steels, manganese steels, and so on,
according to the alloying elements, which give the steel their characteristic properties.
A substance which plays an important part in the type of steel used for construction is the element carbon.
The percentage of carbon in steel directly influences its essential structural properties. An increase in
carbon content results in an increase in strength, but this is accompanied by a marked decrease in
ductility. Ductility, or absence of brittleness, is one of the important requisites of structure steel.

Apparatus
 Universal Testing Machine ( UTM)
 Reinforcement bar with diameter of 20 and length of 1m.
 Strain Gauge
 Caliper
Procedure
 The first step was to measure the diameter of the test bar using a caliper.
 The second step was to fit the test bar in to grips of the testing machine
 Then a strain gauge was fitted on to the bar to read elongation at different loadings
 Gradually increased axial tensile force was applied to failure on the bar and the loading and the
corresponding elongation was recorded at instants.
Calculation
Stresses are determined at different loadings and the resulting strains and plot stress-strain curve for the
tested bar.
The steel is a size of 24 mm.
Area =
𝝅𝑫𝟐
𝟒
= 452.4mm2
Fracture stress = Failure Load /Area = 351.3 MPa
Yield stress = 266.7 MPa
Strain = (Change in length/original Length) * 100
𝟐.𝟓
𝟐𝟎
𝑥 100 = 12.5%
Conclusion
The reinforced bar was elongated by 2.5 cm and finally broke up. And the graph is shown as below.

Determine Silt Content of Sand

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