Harmful ingredients in brick

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
Presentation Link: www.bcivil.weebly.com

Harmful ingredients in brick

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