The cast iron when heated to red heat with powdered red haematite in an oven for increasing its toughness, is converted to
Grey cast iron
White cast iron
Mottled cast iron
Toughed cast iron
Correct Answer :
C. Mottled cast iron
Related Questions
A well seasoned timber may contain moisture up to
4 to 6 %
6 to 8 %
8 to 10 %
10 to 12 %
Pick up the correct statement from the following:
The free quartz suddenly expands at a temperature lower than 600°C
The lime stone resists fire upto about 800°C and at higher temperature it splits into CaO and CO2
The sand stone with silicates resist a fire in a better way
All the above
Bitumen may be dissolved in
Carbondioxide
Water
Sodium chloride
Carbon disulphide
The hardest rock is
Marble
Diamond
Talc
Quartz
Which of the following has more fire resisting characteristics?
Marble
Lime stone
Compact sand stone
Granite
Pick up the constituent of good brick earth whose excess causes the raw bricks shrink and warp during drying and burning, from the following:
Alumina
Lime
Iron-oxide
Magnesia
Pick up the incorrect statement from the following:
Plastics are chemical resistant
Plastics are durable
Plastics are ductile
Plastics are excellent electric insulators
The basic purpose of a retarder in concrete is
To increase the initial setting time of cement paste in concrete
To decrease the initial setting time of cement paste in concrete
To render the concrete more water tight
To improve the workability of concrete mix
According to IS specifications, the compressive strength of ordinary Portland cement after three days should not be less than
7 MPa
11.5 MPa
16 MPa
21 MPa
The amount of water used for one kg of distemper is
0.2 liter
0.4 liter
0.6 liter
0.8 liter
A first class brick when immersed in cold water for 24 hours should not absorb water more than
15 %
20 %
22 %
25 %
Seasoning of timber is done
To make it water proof
To paint its surface
To increase its temperature
To remove water
Pick up the correct statement from the following:
The theory of formation of concrete is based on the phenomena of formation of voids
The bulking of sand is taken into account while volumetric proportioning of the aggregates
The dry sand and the sand completely flooded with water, have practically the same volume
All the above
If the ore impurities is
Clay, lime stone is used as flux
Lime stone, clay is used as flux
Quartz, lime stone and argillaceous iron ores are used as flux
All the above
Stainless steel contains
18% of chromium and 8% nickel
8% of chromium and 18% of nickel
12% of chromium and 36% of nickel
36% of chromium and 12% of nickel
For preparing porcelains, the clay should be
Sufficiently pure
Of high degree of tenacity
Of good plasticity
All the above
Whitworth compressed steel is obtained when molten steel is subjected to a pressure of
5 kg/mm2
9 kg/mm2
13 kg/mm2
15 kg/mm2
Water paint is a
White wash
Colour wash
Whiting
All the above
Cast iron contains carbon approximately
1.5% to 5.5%
0.05% to 1.75%
0.250 %
None to these
The main ingredients of Portland cement are
Lime and silica
Lime and alumina
Silica and alumina
Lime and iron
Most commonly used solvent in oil paints, is
Petroleum
Spirit
Coal tar
Turpentine
Good quality cement contains higher percentage of
Tri-calcium silicate
Di-calcium silicate
Tri-calcium aluminate
Tetra calcium alumino ferrite
Lacquer is
Oil paint
Distemper
Spirit varnish
None to these
Pug mill is used for
Preparation of clay
Moulding of clay
Drying of bricks
Burning of bricks
Rapid hardening cement attains early strength due to
Larger proportion of lime grounded finer than normal cement
Lesser proportion of lime grounded coarser than normal cement
Lesser proportion of lime grounded finer than normal cement
Excess percentage of gypsum
Quick lime is
Calcium carbonate
Calcium oxide
Calcium hydroxide
None of the above
Study the following statements. (i) Hydraulic lime is suitable for white washing, (ii) Fat lime is suitable for whitewashing, (iii) Hydraulic lime is suitable for making mortar, (iv) Fat lime is suitable for making mortar. The correct answer is
(i) and (iv)
(ii) and (iii)
(i) and (ii)
(iii) and (iv)
Rocks formed due to alteration of original structure due to heat and excessive pressure are called
Sedimentary rocks
Igneous rocks
Metamorphic rocks
None of these
Plastic asphalt is
Used as a water proofing layer over roof
A mixture of cement and asphalt
A natural asphalt
A refinery product
The frog of a brick is normally made on its
Top face
Bottom face
Longer face
Shorter side