Moon PowerPoint Template

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Testing of Cement
Field Test
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Colour
Physical properties
Presence of lumps
Strength
Colour should be uniform
Typical cement colour (gray colour with
light greenish shade)
It gives an indication of excess of lime or
clay and the degree of burning.
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Physical properties
• Feel smooth when touched or rubbed in between
fingers.
• If felt rough, indicates adulteration with sand.
• If hand is inserted in cement bag, hand feels cool
and not warm.
• If it immersed in water, it should sink and should
not float
• A paste of cement feel sticky
• If it contains clay & silt as adulterant, it
give earthy smell.
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Presence of Lumps
• It should free from hard lumps.
• It is due to the absorption of moisture from
atmosphere.
• If a bag contains lumps it should be
rejected.
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Strength
• It is tested by three methods:
1. Briquettes with a lean or weak mortar are
made (75mm x 25mm x 12mm).
The proportion of cement & sand is 1:6.
Immersed in water for 3 days.
• If cement is good it will not be broken easily
and difficult to convert powder form.
2. A block is prepared (25 x 25 x 200) and
immersed in water for 7 days.
• Then it is placed on supports 150 mm
apart and loaded 340N.
• It should not show signs of failure.
3. Thick paste of cement with water is made
on thick glass and kept in water for 24
hours.
• It should set and not crack.
Laboratory test for Cement
• When cement is loose:
φ Sample is taken from at least 12 points
from heap.
• When cement is in bags:
φ At least from 12 different packages or
bags.
Purpose of testing
• To determine physical & chemical
properties
• To regulate the various stages in
manufacturing
• Behavior of cement
Standard Tests
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Chemical composition
Fineness
Compressive strength
Tensile strength
Consistency
• Setting time
• Soundness
Chemical Composition
• Ratio of alumina to iron oxide < 0.66
• Lime saturation factor (LSF):
 Ratio of lime to Al2O3, Fe2O3 & SiO2
0.66 > and < 1.22
CaO – 0.7 so3
2.8 sio2 + 1.2 al2o3 + 0.65 fe2o3
• Total loss on ignition should < 4%
• Total Sulphur content < 2.75%
• Weight of insoluble residue < 1.5%
• Weight of Magnesia < 5%
Fineness
• Sieve test is conducted with the standard BIS
sieve no. 9.
• 100g is taken and sieved for 15 min
• The residue should < 10%
• In Permeability apparatus test, specific surface
area is calculated;
•It should not < 2250 cm2/g
•It gives the idea of uniformity of fineness
Compressive strength
• Mortar of cement & sand is prepared, 1:3.
• Water is added, water cement ratio 0.4:1
• It is placed in moulds & form cubes of sides 70.6
or 76 mm.
• The cement required is 185 or 235g
• Compacted in vibrating machine in 2 min.
•Moulds placed in damp cabin for 24 hrs
•Specimens are removed & placed in
water for curing.
• It is tested in compressive testing machine
after 3 and 7 days.
• Every side is calculated and average is
taken.
• For 3 days: > 115 kg/cm2 or 11.5 N/mm2
• for 7 days: > 175 kg/cm2 or 17.5 N/mm2
Tensile Strength
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Formerly used to have indirect indication
for compressive strength
• At present used for rapid hardening test.
• Procedure:
1. Mortar is prepared cement(1) : Sand (3)
2. Water is added 8%
3. Mortar is placed in briquette moulds.
• Typical briquette is formed.
• A small heap is formed at its top.
• It is beaten down by a standard spatula till
water appears on the surface.
• Same procedure is repeated for other
sides of briquettes.
• 12 standard briquettes are prepared
• The quantity of cement may be 600g for
12 briquettes
• It is kept in damp cabin for 24 hrs.
• It is carefully removed from mould and
submerged in clean water for curing.
• It is tested in testing machine after 3 and 7
days.
• The load is applied at the rate of 35
kg/cm2
• The cross section of briquettes at least
section is 6.45 cm2
• Ultimate tensile stress = failing load
6.45
• After 3 days: > 20 kg/cm2
• After 7 days: > 25 kg/cm2
Consistency
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It is used to determine the % of water
required for preparing cement pastes for
other tests
• Procedure:
1. Take 300g cement, add 30% or 90g of
water
2. Mix water and cement on a non-porous
surface. Mixing should be done.
• Fill the mould of Vicat apparatus.
• The interval between the addition of water
to the commencement of filling the moulds
is known as the time of gauging.