This set of Engineering Chemistry Questions and Answers for Campus interviews focuses on “Construction Material Cement”.
1. Which type of cement possesses hydraulic qualities?
Explanation: Natural cement possesses hydraulic qualities. The fast-setting Rosendale natural cement mortars proved to be more efficient than the mortars based on lime and sand.
2. Select the incorrect statement from the following options.
a) Puzzolona is the oldest cement invented by Romans
b) Natural puzzolona is deposit of volcanic ash
c) Puzzolona was used in making concrete for construction of walls and domes
d) Puzzolona is quite setting cement and posses relatively low strength
Explanation: Natural cement is quite setting cement and posses relatively low strength. All the other options are correct. Puzzolona is the oldest cement invented by Romans, used in making concrete for construction of walls and domes.
3. Blast furnace slag is the mixture of
a) Slaked lime and calcium silicate
b) Aluminium silicate and hydrated lime
c) Calcium silicate and aluminium silicate
d) Silica, alumina and calcium oxide
Explanation: Blast furnace slag is the mixture of Calcium silicate and aluminium silicate. Ground-granulated blast-furnace slag is obtained by quenching molten iron slag (a by-product of iron and steel-making) from a blast furnace in water or steam, to produce a glassy, granular product that is then dried and ground into a fine powder.
4. Portland cement is made by calcining at temperature equals to
Explanation: Portland cement is made by calcining at temperature equals to 15000C. It is manufactured from chalk and clay which hardens under water and when hard resembles Portland stone in color.
5. Why Gypsum is added after calcination in the manufacture of Portland cement?
a) To prevent flash setting
b) To improve the quality of cement
c) To increase the lime saturation factor
d) None of the mentioned
Explanation: Gypsum is added after calcination to prevent flash setting and it acts as a retarder.
6. Who is recognized as the “Father of the modern Portland cement industry”?
a) Emil Abderhalden
b) Richard Abegg
c) Peter Agre
d) William Aspdin
Explanation: William Aspdin is recognized as the “Father of the modern Portland cement industry”. Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout.
7. All portland cements are hydraulic cement because of they
a) Set and harden in the absence of water
b) Set and harden in the presence of water
c) Do not harden after mixing water
d) None of the mentioned option
Explanation: All portland cements are hydraulic cements because they set and harden under water. This cement not only hardens by reacting with water but also forms a water-resistant product. Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout.
8. The percentage composition of alumina in Portland cement is
Explanation: The percentage composition of alumina in portland cement is 3-8 %. Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates, the remainder consisting of aluminium- and iron-containing clinker phases and other compounds.
9. Which compound causes the cement efflorescent, if present in excess?
a) Iron oxide
b) Alkali oxide
c) Sulphur trioxide
Explanation: Alkali oxides causes cement efflorescent if present in excess. The alkali metals react with oxygen to form several different compounds: suboxides, oxides, peroxides, superoxides, and ozonides.
10. Which compound imparts grey color, strength and hardness to the portland cement?
a) Iron oxide
c) Magnesium oxide
Explanation: Iron oxide imparts grey color, strength and hardness to the portland cement.
Sanfoundry Global Education & Learning Series – Engineering Chemistry.
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