Related Questions

An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture?
A Cork
B Saw dust
C Sand
D Chemically prepared foam
Porosity of fireclay refractories is __________ percent.
A 5-10
B 10-25
C 25-35
D 35-50
Addition of grog in fireclay brick during its manufacture is advantageous, because it results in
A Less shrinkage in heating, decreased apparent porosity & increased specific gravity
B High strength & thermal spalling resistance
C Less addition of water to get a workable plasticity & lesser time required for drying the raw refractories and hence increased rate of production
D All of the above
Grog addition in fireclay during brick manufacture is done to
A Reduce its shrinkage on heating
B Impart greater spalling resistance
C Enhance the strength of fired refractories
D All of the above
The solid brick shown is made of small square shaped bricks of side 1. when the large brick is disassembled into its component small bricks. the total surface area of all the small bricks is how much greater than the surface area of the large brick?
A 32
B 40
C 60
D 72
The method of moving each brick through a small horizontal distance before it is finally laid in any brick wall and pressing it by means of brick hammer, is known as
A Troweling
B Laying
C Grouting
D Placing
Thermal spalling mainly occurs during __________ of furnaces.
A Cooling down
B Warming up
C Both A & B
D Neither A nor B
Spalling resistance of a refractory can not be increased by
A Increasing its porosity
B Using a coarser grog during its manufacture
C Decreasing its thermal co-efficient of expansion
D Making it denser
With increase in porosity, the thermal conductivity of a solid substance
A Increases
B Decreases
C Remains unchanged
D May increase or decrease; depends on the solid
Spalling hammer is used for
A Driving wooden headed chisels
B Rough dressing of stones
C Carving of stones
D Breaking small projection of stones

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