This set of Building Construction Multiple Choice Questions & Answers (MCQs) focuses on “Plain and Reinforced – Cement – 2”.
1. The specific surface of cement should not be lesser than __________
a) 550 cm2/gm
b) 1250 cm2/gm
c) 2250 cm2/gm
d) 5250 cm2/gm
Explanation: The specific surface serves as a measure of the frequency of particles having an average size. The specific surface of cement should not be lesser than 2250 cm2/gm.
2. ___________ is the binding material of acid-resistant cement.
b) Soluble glass
c) Soda ash
d) Caustic soda
Explanation: Soluble glass is the binding material of acid-resistant cement. It is a water solution of potassium silicate or sodium silicate.
3. Sodium fluosilicate added in the acid-resistant cement decreases the resistance of cement to water and acid and also retards the hardening process of soluble glass.
Explanation: An acid-resistant cement consists of acid-resistant aggregates like quartz, additives like sodium fluosilicate and soluble glass. Sodium fluosilicate added in the acid-resistant cement increases the resistance of cement to water and acid and also accelerates the hardening process of soluble glass.
4. The resistance to water of acid-resistant cement is increased by adding ______ of linseed oil.
Explanation: Acid-resistant cement is not water-resistant. However, the resistance to water of acid-resistant cement is increased by adding 0.50% of linseed oil. It is then called acid and water-resistant cement.
5. The presence of chromium oxide in cement imparts _____ colour.
Explanation: We can obtain cement of desired colour by mixing mineral pigments with the ordinary cement. The presence of chromium oxide in cement imparts a green colour.
6. Expanding cement is obtained by the addition of an expanding medium like _________ to the ordinary cement.
a) Sodium silicate
b) Potassium silicate
c) Sodium aluminate
Explanation: Expanding cement is obtained by the addition of an expanding medium like sulpho-aluminate to the ordinary cement. Therefore, the expanding cement expands while all other cements shrink. It is used to repair the damaged concrete surfaces.
7. The presence of cobalt in cement imparts _____ colour.
Explanation: The presence of cobalt in cement imparts blue colour. However, manganese dioxide is used to give black or brown coloured cement and oxide of iron in various proportions provide brown, yellow or red colour.
8. In England, high alumina cement is known by the trade name of ___________
b) Lumnite Fondu
d) Cement Fondu
Explanation: In England, high alumina cement is known by the trade name of Cement Fondu. However, in America, it is known by the trade name of Lumnite. This cement can stand high temperatures.
9. The total alumina content in high alumina cement should not be less than _______
Explanation: The total alumina content in high alumina cement should not be less than 32%. Also, it is specified that the ratio of alumina to lime by weight should lie between 0.85-1.30.
10. The final setting time of high alumina cement is about _______
a) 30 mins
b) 2 hours
c) 5 hours
d) 24 hours
Explanation: The final setting time of high alumina cement is about 5 hours. The setting action of this cement mainly depends on the chemical reactions and therefore it is not essential to grind it to a fine powder. Great amount of heat is evolved during setting.
11. Which of the following is not a hydrophobic admixture?
a) Lime silicate
d) Oxidised petrolatum
Explanation: Hydrophobic cement consists of admixtures which are used to reduce the wetting ability of the cement grains. The usual hydrophobic admixtures used are acidol, oxidised petrolatum and naphthenesoap.
12. Which of the following is not true about pozzuolana cement?
a) Pozzuolana cement can resist the action of sulphates
b) Less heat is evolved during its setting
c) Pozzuolana cement possesses a very low tensile strength
d) It imparts plasticity to the mortar prepared from it
Explanation: Pozzuolana cement possesses higher tensile strength and can resist the action of sulphates. It imparts plasticity to the mortar prepared from it and less heat is evolved during its setting.
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