UNESCO-NIGERIA TECHNICAL & VOCATIONAL EDUCATION

REVITALISATION PROJECT-PHASE II

YEAR I- SE MESTER II

PRACTICAL Version 1: December 2008

NATIONAL DIPLOMA IN

BUILDING TECHNOLOGY

BUILDING SCIENCE AND PROPERTIES OF MATERIALS II

COURSE CODE: BLD102

TABLE OF CONTENT

WEEK 1 Electrical Effects: Electro- Dynamic Effects Experiment

WEEK 2 Clay Brick WEEK 3 Hand - Made Bricks WEEK 4 Pressed Bricks Experiment WEEK 5 Determination of Crushing Strength of Bricks Week 6 Strength Tests on Limes WEEK 7 Effect of Grading of Aggregate on the Properties Of Concrete WEEK 8 Slump Test WEEK 9 Compacting factor test

WEEK 10 V.B Consistometer test WEEK 11 Determination of the Strength of Concrete WEEK 12 Soundness of Cement Test Week 13 Field Setting Test to Determine Silt Content WEEK 14 Soundness of Cement Test Week 15 Students Excursion

WEEK 1

ELECTRICAL EFFECTS: ELETRO- DYNAMIC EFFECTS ;EXPERIMENT

Electric currents and magnetic fields have important mutual effects.

.If an electric current is passed through a wire that is situated in a magnetic field

as shown in the figure below in {a}

Figure Force on a conductor in a Magnetic Field

.The wire tends to move, in the direction motion cutting the lines as shown above

in {b} it is on this effect that the operation of an electric motor depends. Both

explained the principle of electric motor.

.If a current is passed through a coil of wire suspended in a magnetic field as

shown at {a}, the action on each side of the coil is to cause rotational in the

direction shown.

.when the coil passed the vertical position {b}, a change in the direction of the

current is necessary if rotation is to continue in the same direction.

.If a conductor is moved across the line of force in a magnetic field, a current will

be generated in it. The direction of movement of conductor and the current flow

as shown in figure below explained the Principle of the Dynamo, the machine by

which electricity is mostly generated.

Details of the principle are illustrated below;

Figure Dynamo principle

For the direction of rotation shown at {a} current will flow in the coil as shown ;

as the coil approaches the vertical position{b}, the current dies away because, in

the position, the conductors are not cutting the line of force , but are running

parallel to them. In position {c} the direction of flow is revered, and is at its

maximum with the coil in the horizontal direction, dying away to zero in

position {d} .this type of output is known as alternating Current.

WEEK 2 Clay Brick

Procedure:

In manufacturing of clay bricks, it is usual first to grind the clay with water

to reduce it to the required plasticity for molding. Sometimes two or more

types of clays are mixed in order to produce a more suitable material. The

plastic clay is then molded into bricks, which are dried and then burned at

a high temperature (about 850 1,1000c) in kilns. The burning process

hardens the clay and gives the bricks the strength and durability required.

WEEK 3

Hand - Made Bricks:

Bricks are moulded by hand from clay which contains sufficient

water to render it thoroughly plastic, and the finished product

usually has a high porosity (about 28 - 35 percent). Their

durability is, however, quite satisfactory except where

temperature of burning are not high enough. Under - burned

bricks may be recognized by their lightness in colour and lack

of ring when stucks, and should not be used for building

work. Hand made bricks are usually sand faced, since the

moulds are dusted with sand to prevent the clay sticking. This

gives to the bricks a surface texture which contributes greatly to

their good appearance.

WEEK 4

Pressed Bricks Experiment

Plastic type: The strongest of all clay bricks are made by moulding under high pressure. Porosities as low as 8 percent

may be obtained by this means, and the bricks are afterward

burned at a temperature sufficiently high to give them a

vitreous surface.

Semi - Dry or Semi Plastic type: Bricks are also moulded by repeated pressing of clay containing minimum water content.

High moulding pressures are generally used but high density is

not always achieved. In fact, English example of this type of

brick frequently have porosities greater than 25 per cent,

though this may be due to the nature of the clays used rather

than to the process itself. The low moisture content allows

considerable economies to be achieved in burning, and also

much reduces volume and shape change during burning;

semi-dry bricks are notable for their regularity of size and

shape.

WEEk 5

Determination of Crushing Strength of Bricks

Procedure;

Three whole bricks should be selectee from each batch to be tested

and the overall dimensions of each bed face (see Fig. Week5) of

each brick measured to the nearest 300mm. The area of the face

having the smaller area is taken as the area of the brick for

calculating the compressive strength.

Bricks without frogs are immersed in water for three days before

testing.

Bricks with frogs are immersed in water for twenty-four hours. They

are then removed from the water, allowed to drain for about five

minutes, wiped free from surplus moisture, and their frogs filled

with mortar composed of 1 part by weight of Portland cement to 1

Bed Face

Figure Week5

parts of sand. The bricks are stored under the damp sacks for twenty-

four hours and afterwards in water until tested seven days after the

frogs have been filled.

The bricks are crushed between sheets of 3-ply wood 3mm thick.

A very large-capacity testing machine is necessary to crush whole

bricks of the stronger types. If the capacity of the machine available is

limited to 100 tons or to a lower value, the strengths of bricks may be

compared by tests on quarter-bricks, the frogs being filled as required

for whole bricks. The strengths obtained will be lower than if whole

bricks were tested.

The strength of bricks is dependent mainly on method of molding

and on burning temperature, high strengths being associated with

low porosity and high burning temperatures.

WEEK6 STRENGTH TESTS ON LIMES

Mix 300 gram. of hydrated lime with 195ml of water for five

minutes. Mix the putty thoroughly with 900 gram of standard cement

testing sand, and fill six 4 in x 1-in 1-in moulds. The moulds should

be filled by pressing with the thumbs and smoothed off with a palate

knife. The specimens are stored in moulds in moist air in a slightly

warmed oven (250c) for twenty eight days. They are then removed

from moulds and stored in water half an hour before being tested

transversely on a 3-in span.

This experiment may be carried out using hydrated limes of the

following types

a. non hydraulic

b. semi hydraulic

c. hydraulic and

d. 75 per cent. Non hydraulic lime: 25 per cent Portland cement

e. Portland cement. The quantity of water used may have to be

varied to suit the requirements of different materials

WEEK 7 EXPERIMENT; EFFECT OF GRADING OF AGGREGATE ON THE

PROPERTIES OF CONCRETE

Mixes are prepared consisting in each case of 1 part (by weight) of cement and 6

parts aggregate. (48.5kg of cement and 20.1kg) of aggregate give a quantity

soluble for making one 4 in cube. In different mixes, the proportions of fine and

coarse aggregate are varied, in table 11 are given mixes whose proportion

provide

Table 11

Proportions by weight

Mix Cement Sand Gravel

A

B

C

D

E

F

1

1

1

1

1

1

6

4

3

2

1

0

0

2

3

4

5

6

A suitable range for observation of the effects of grading of aggregate on the

properties of concrete. Each mix is gauged with sufficient water to produce a

plastic, workable mix, an attempt being made to produce mixes of comparable

workability. The amount of water required for each mix is carefully noted and

the character of each mix is examined by working it with a trowel. A test

specimen is then made from mix, care being taken to compact the concrete

thoroughly, and its crushing strength determined after seven days or other

convenient interval. A typical set of result from the experiment are given in the

following table.

Table 12

Effect of aggregate grading on concrete properties

Mix Water content percentage by weight of

cement

Crushing strength at seven days

lb. per square inch

A

B

C

D

E

F

86

73

66

60

49

40

280

88

1,480

2,220

1,760

730

It will be observed that, as the proportion of fine aggregate in the mix increase,

so also does the amount of mixing water required. Also mixes E and F, deficient

in sand , will be found to work very harshly, and no amount of added water will

make them plastic. Mixes, A,. B and C on the other hand, provided sufficient

water is added, give very attractive mixes, plastic and workable. From the

appearance of the cubes and the crushing test results, mix F will be seen to be

very porous, and not very strong; mix E though still porous, should give good

strength. The other mixes appear satisfactorily dense, but the strength will fall off

rapidly from mix D, which should give good strength not very different from

mix E, to mix A, whose strength will probably be even lower than that of F

whose appearance is so unpromising.

WEEK 8

TITLE: SLUMP TEST

OBJECTIVE:

To assess the workability of concrete.

Apparatus:

Truncated conical mould 100mm diameter at the top, 200mm at the

bottom and 300mm height.

Steel tamping rod 16mm diameter, 600mm long rounded at one end,

Diagram:

Figure: slump cone

Theory:

The slump is the difference between the height of concrete before

removing a slump cone and after removing it.

Procedure:

1. The inside of the mould should be cleaned before each test

and the mould placed on a hard, flat, impervious surface.

2. The mould should be filled in three layers of concrete of

approximately equal depth. Each layer is rode with 25 stokes

of the rounded end of the tamping rod; after the top layer

has been rode, the surface of the concrete is struck off level

with the top of the mould with a trowel or the rod. Any

spillage is cleaned away from around the base of the mould,

and the mould is then lifted vertically from the concrete.

3. The slump is the difference between the height of the

concrete before and the greatest height after the removal of

the mould. If any specimen collapses or shears off laterally,

the test should be repeated with another sample of the same

concrete; if in the repeat test, the specimen should again

shear; the slump should be recorded together with the fact

that the specimen sheared.

4. If after the slump measurement has babe completed, the side

of the concrete is tapped with a rod, a well-proportioned

cohesive mix will gradually slump further but a harsh no

cohesive mix is likely to collapse.

WEEK 9 Title: compacting factor test

Objectives:

This test is a more sensitive method of measuring the workability of

concrete than the slump test, as it is designed to give a figure as a

measure of workability for any kind of concrete mix made with

aggregate not over 38mm maximum size.

Apparatus:

Compacting factor apparatus

Hand scoop

Balance capable of weighing 7kg and accuracy 1g

Trowel;

Diagram

Figure: compacting factor apparatus

Theory:

Included in procedure:

Procedure:

1. The doors of the hoppers are closed and the lower cylinder is

fixed centrally in position and covered.

2. The top hoppers filled with the sample of concrete of this

hopper is released and the concrete is allowed to fall into the

lower hopper; than the concrete is similarly released from

the lower hopper and fall into the cylinder. Cohesive mixes

have a tendency to stick in one or both of the hoppers, and, if

this happens, the concrete may be helped through by

pushing a rod gently into the concrete from the top.

3. The excess concrete is struck off by two trowels working

inwards and the full cylinder then removed and weighed,

giving the partially compacted weight.

4. The cylinder is emptied ad refilled in layers approximately

50mm deep and heavily rammed or vibrated (if of low

workability), and completely filled. The concrete in the

cylinder is again weighed.

Compacting factor (CF) = 1st net weight

2nd net weight

A higher value indicates greater workability.

WEEK 10 Title: V.B Consistometer test

Objective:

This test can be regarded as an extension of the slump test which

is performed in the same apparatus, being the first part of this test.

Apparatus:

a. Consistometer (see figure) consisting of a vibrating table T,

on which is fixed a cylinder container C. A slump cone S (of

size as for slump which rest centrally in the container. A

funnel F is held on a; swivel arm A, for filling with concrete.

On the swivel arm on the opposite side is a rod R, holding a

transporatent disc D, with a weight w (270g) including the

rod and disc).

b. Tamping road, 16mm diameter, 600mm long.

c. Stop watch accuracy 0.5s.

Diagram

Figure: V-B Consistometer

Theory:

Included in the procedure

Procedure;

1. The cone is filled with concrete as for the slump test. The set

screw G is loosened and the funnel is swung to one side. The

surface of the concrete is struck off. The mould is removed

carefully and the slump is measured if required. This can be

done when the disc is swung round into position and

lowered down the rod just to touch the slump concrete. The

slump may be read off the rod scale.

2. With the arm fixed in this position, holding the disc resting

on the concrete and with stop watch ready, thee watch is

started the instant that vibration is begun; and the watch is

stopped at the moment the concrete has been fully

compacted as compacted as observed through the disc, i.e

when the disc is fully covered underneath with cement

grout. The result is the time in seconds recorded to nearest

0.5s being expressed as V-B degrees.

An approximate guide to compacting factors, slump, and vebe

degrees suitable for concrete for different purposes are given in

the following table:

The presence of salt salts out and coagulates the colidal particles

which may be present, and which otherwise would remain in

suspension in the water layer.

WEEK 11 DETERMINATION OF THE STRENGTH OF CONCRETE After the casting of concrete, the concrete should be cured for 7 days -14 days. .To demonstrates to student how Schmidt Hammer is used to determine the strength of concrete on site. .the lower pitch sound indicates that the strength of the concrete is low. .The higher pitch sound gives the higher strength of concrete. Week. 12 Title: SOUNDNESS OF CEMENT TEST Objectives: To Determine the Soundness of cement test. Apparatus: le chatelier apparatus Diagram Procedure

mix10gofcementwiththequantityofwaterrequiredtogiveapasteofstandardconsistency,vigorouslyfor240sonanonporoussurfacebymeansoftwotrowels.

Placethemouldononeglassplateandfillitwiththepastetakingcaretokeepthesplitofthemouldgentlyclosedwhilethisoperationisbeingperformed.

Coverthemouldwithotherglass,uponwhichasmallweightisplaced. Immersethewholeimmediatelyinwateratatemperatureof20+10Candleavethese

fortwentyfourhours.

Removethemouldfromthewaterthenmeasurethedistanceseparatingtheindicatorpointstothenearest0.5mm.

Immersethewholeandbringthewatertoboilin2530minutesandkeepboilingfor1hour.

Removethemouldfromthewatertocool. Measurethedistanceseparatingtheindicatorpointtothenearest0.5mm.

Result

The difference between the two measurements represents the expansion of the cement to the nearest 1mm

Week 13 FIELD SETTING TEST TO DETERMINE SILT CONTENT Prepare an approximately 1m solution of common salt by dissolving 2.5g of sodium chloride in 250ml of tap water. Pour 50ml of this solution into a 250ml measuring cylinder and then add sand until the volume of sand is about 100ml; add more of the salt solution until the total volume in the measuring cylinder is 150ml. Placing the palm of the hand over the open end of the cylinder, shake vigorously, place on a level bench, tap until the sand surface is level. Allow to stand for three hours. Record the height of the sand, and of the silt above it.

Calculate the percentage of silt present. Report on the suitability of the sand as fine aggregates in the preparation of

concrete.

Note: the presence of salt out and coagulates the colloidal particles which may be present and which otherwise would remain suspension in the water layer.

WEEK 14

Title: Soundness of Cement Test.

Objective: To determine Soundness of Cement

Apparatus: Le Chatelier Apparatus

See week 7 for the theoretical explanation of this test.

Mix 10g of cement with quantity of water required to give a paste standard consistency vigorously for 240s on a non porous surface by means of two trowels.

Place the mould on one glass plate and fill it with paste taken care to keep the split of the mould gently closed while this operation is being performed.

Cover the mould with other glass, upon which a small weight is placed. Immerse the whole immediately in water at a temperature of 20 10C and leave

these for twenty four hours.

Remove the mould from the water then measure the distance separating the indicator points to the nearest 0.5mm.

Immerse the whole and bring the water to boil in 25 30 minutes and keep boiling for 1hour.

Remove the mould from the water to cool. Measure the distance separating the indicator point to the nearest 0.5mm.

Result

The difference between the two measurements represents the expansion of the

cement to the nearest 1mm

WEEK 15. STUDENTSEXCURSION. Pictures on excursion from Ajaokuta steel rolling mill at Kogi state, Nigeria.

The process of the production is described by the arrows.

CoverTABLE OF CONTENTWEEK 1WEEK 2WEEK 3WEEK 4WEEk 5WEEK 6WEEK 7WEEK 8WEEK 9WEEK 10WEEK 11Week. 12Week 13WEEK 14WEEK 15.Return to Table