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Presentation: 1
HARMFUL INGREDIENTS IN BRICK
1zubair4kb@gmail.com

Group: 1
Muhammad Zubair
M. Mahmood-Ul-Haq
Tasawar Iqbal
M. Ansar Hayyat

Necessary Ingredients of Brick
Affecting The Brick Quality
? Alumina
? Silica
? Lime
? Oxide Of Iron
? Magnesia

Alumina
? Alumina is main constituent of every clay
? It imparts plasticity
? It becomes very hard on burning
? A good brick-earth should contain 20 to
30 percent of Alumina
? Excess amount of alumina causes
shrinkage and warping of bricks during
drying and burning

Silica
? Presence of silica prevents cracks,
shrinking and warping of raw bricks
? Imparts uniform shape to the bricks
? Durability of bricks depends on the proper
proportion of silica in brick-earth
? A good brick-earth should contain about
50 to 60 percent
? Excess amount destroys the cohesion
between particles and brick becomes brittle

Lime
? A small quantity of lime is desirable in finely
powdered state to prevents shrinkage of raw
bricks
? It helps to lower the fusion temperature
? It also prevents shrinkage of raw bricks
? It helps to bind the particle together
? Should not exceed 5%
? The excess of lime causes the brick to melt
and hence its shape is lost.

Oxide Of Iron
? Imparts Red Color to the Brick
? It helps to fuse sand.
? A good brick-earth should contain about 5
to 6 percent
? Excess amount makes brick dark blue or
blackish and lesser amount makes it
yellowish

Magnesia
? It imparts yellow tint
? It is responsible for reducing shrinkage
? A good brick-earth should contain about1%
magnesia.
? Excess amount leads to the decay of bricks

Composition of Good brick-earth
? Alumina ( 20 to 30 %)
? Silica (50 to 60 %)
? Lime (A small quantity)
? Oxide of iron ( 5 to 6 %)
? Magnesia (A small quantity)

Harmful Ingredients in bricks
? Lime
? Iron pyrites
? Alkalis
? Vegetation and organic matters
? Pebbles

Lime
? Lime is one of the most dangerous
minerals
? The lime present in the brick is converted
into quick lime during burning process
? This quick lime slakes and expands in
presence of moisture
? As a result of which the brick splits or
bursts into pieces

Test for Determining Presence of
Lime in Brick-Earth
? Take a representative soil sample.
? Ground the soil into a loose form by hand
? Place a small amount of soil in the Petri dish
? Take a small amount of acid by a pipette and
put it over the soil sample in the Petri dish.
? Observe the reaction it creates.
? Lime is present if the reaction causes
effervescent (type of melting) or bubbling
action.

Iron Pyrites
? Iron Pyrite also affects the brick quality.
? Bricks are crystallized and disintegrated
during burning because of the oxidation
of iron pirates.
? Pyrites decolorize the bricks

Alkalis
? Alkalis exist in the brick earth in the form
of soda and potash
? Alkalis present in the brick earth lower the
fusion temperature abnormally as a result
of which the brick deforms and twists
? Alkalis absorb water from atmosphere
and make the walls damp
? When the moisture in the wall evaporates,
they leave behind efflorescence spoiling
the appearance of the building

Vegetation and organic matters
? The presence of vegetation and organic
matter in brick earth assists in burning.
? But if such matter is not completely burnt,
the bricks become porous.
? This is due to the fact that the gasses will
be evolved during the burning of the
carbonaceous matter and it will result in
the formation of small pores.

Pebbles
? Pebbles in brick earth create problem
during mixing operation of earth
? It prevents uniform and thorough mixing
of clay, which results in weak and porous
bricks
? Bricks containing grits mostly crack and
cannot be readily cut or worked.

Best Of Luck
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Harmful ingredients in brick

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