TILES
Common Tiles
Uses: roofing,
flooring, paving,
drains, walls
Encaustic Tiles
Uses:
decorative
purposes in
floors, walls
MANUFACTURE OF TILES
• PREPARING OF CLAY
• MOULDING CLAY
• DRYING
• BURNING
1. Preparation of clay:
 Suitable clay for tiles is ground into fine powder in pug mills.
 Powdered clay is mixed with large quantity of water in a
tank.
 Coarse heavy particles settle at the bottom of tank whereas
finer particles are taken into the lower tank.
 Water is allowed to dry off & fine clay left after such process
is used for manufacture of tiles.
 Sometimes, a mixture of ground glass & pottery-ware is
added to clay to make the tiles hard & impervious
2. Moulding:
 Clay is filled in moulds which represent the exact pattern or shape in
which tiles are to be produced.
 Done with wooden moulds or mechanical means or potter’s wheel.
3. Drying:
 Moulded tiles are placed flat one above the other in form of heaps.
 After 2 days, the irregularity of tiles due to warping is corrected by
slightly beating them with a flat wooden mallet.
 After cleaning the edges, tiles are stacked on edge under a shade,
which prevents warping & cracking of tiles due to rain & sun.
4. Burning:
 The tiles are then burnt in kilns.
 A typical kiln, known as Sialkote Kiln , for accommodating about
30000 to 40000 tiles.
 Circular in shape & is protected by a shed.
 A layer of bricks is laid flat on the rows of long narrow flues.
 The burning is effected by firing wood placed in these flues.
 The bricks are arranged in such a way that open spaces are left in b/w
them.
 Above the layer of bricks, the dried tiles are placed on edge layer by
layer.
 The closing of doorways is effected by brickwork in mud.
 The top of kiln is covered with a layer of old tiles placed in a loose
condition.
 Regulation of heat is important.
 Fire is gentle in the beginning. It
removes moisture.
 It is then raised to about 800°C.
 It is slackened for a period of
about 6hrs & then raising the
temp. to white heat (1300°C).
this temp. is maintained steady
for a period of 3hrs. This process
is repeated.
 The flues are filled with the fuel
& the doorways are closed by
brickwork in mud.
SIALKOTE KILN
 The kiln is then gradually allowed to cool down. It requires
about 72hrs to complete the process of burning the tiles.
 The tiles are taken out of the kiln.
 The underburnt tiles are sorted out & they are placed on the
top of kiln in the subsequent burning of tiles.
 It is thus seen that this kiln is an intermittent kiln.
Test on Tiles
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Water absorption
Crazing resistance
Bond strength
Thermal shock resistance
Modulus of rupture
Moisture expansion
Scratch hardness
Water absorption
• In this test method, water absorption of tile specimens is
calculated based on a five hour boiling water method. This test
is used to determine the degree of maturation of the ceramic
tile body or for evaluating structural properties that may be
required during installation.
• Five (5) test pieces, weighing at least 50 grams and cut from
the center of whole tiles are required for one test. Test pieces
are dried to a constant mass, weighed and placed in boiling
water for five hours then soaked in room temperature water for
24 hours. Wet weights are determined after soaking for 24
hours. The difference in weights of test pieces before and after
boiling is used to calculate percent water absorption
Crazing resistance
• This method evaluates resistance of tile specimens to crazing.
• Test specimens are subjected to heat and steam under pressure
and evaluated for crazing failure. Test pieces are observed
visually with the aid of oblique lighting and inks or dyes to
identify crazing failures.
• Ten (10) whole tiles having facial dimensions of 6" × 6" or 6"
× 8" or less are required for one test. For larger tiles, five (5)
whole tiles are required which are cut and tested.
Bond strength
• In this test method, the bond strength between tile specimens
and a mortar bed when bonded with portland cement paste is
determined. The test method may be used to evaluate glazed
ceramic wall tile, ceramic mosaic tile, quarry tile, pressed floor
tile, and porcelain tile. This method also includes both facemounted and back-mounted tile.
• Five (5) whole tiles are required for a single test. The test
specimens are bonded to a mortar bed and cured for seven
days to create the test assembly. Once cured, the bond strength
is assessed by applying a shear load force until bond failure.
The results are reported in pounds per square inch (psi) units
and the nature of failure is also included in the test report.
Thermal shock resistance
• Resistance of tile specimens to thermal shock under normal
conditions of use is determined. The test pieces are subjected
to alternating low and high temperatures and visually observed
for defects with the aid of inks or dyes.
• Ten (10) whole tiles are required for a single test. The test
pieces are subjected to ten cycles of alternating temperatures
of 15 ± 5˚C and 145 ± 5˚C. Depending on the water absorption
value of the test pieces, the test method includes two
procedures, with or without immersion in water. The test
pieces are inspected for damage as a result of temperature
cycling.
Modulus of rupture
• Modulus of rupture of tile specimens is determined by this test
method. The test method is applicable to both glazed and
unglazed tiles.
• Ten (10) whole tiles are required for a single test. Test pieces
are supported by two beams and a direct load is applied by a
single loading beam in the center until breakage occurs.
Moisture expansion
• In this test method, moisture expansion of ceramic tiles is
determined. Moisture expansion is achieved by heating tiles in
boiling water and measuring the proportional change in length.
• Five (5) test pieces of size 1" × 4" are required for a single test.
Test pieces are re-fired in a kiln and placed in boiling water for
24 hours after initial length measurements. Moisture expansion
is calculated from the difference of length measurements
before and after boiling.
Scratch Hardness
• In this test method, the resistance to scratching of ceramic tile
is evaluated using the Mohs scale of mineral hardness. The
ceramic tile surface is scratched using the mineral from each
hardness class.
• Three (3) whole tiles are required for a single test. The highest
number mineral on the Mohs scale that does not scratch the tile
surface is reported.
TESTS ON TILES
• FLEXURAL STRENGTH TEST
• PERMEABILITY TEST
• WATER ABSORPTION TEST