This set of Concrete Technology MCQs focuses on “Factors Causing Variation in the Quality of Concrete”.
1. Generally what is the w/c ratio?
Explanation: Generally the water cement ratio is .42-.5 and if it exceeds it will create pores in concrete.
2. The slump would not exceed 50 mm when compacting concrete with vibrators.
Explanation: Segregation means concrete cement slurry & fine aggregates &coarse aggregate collapsed & have no slump & after hardening no strength but workability is the checking the concrete how much time used after mixing.
3. The levelling operation that removes humps and hollows and give a true, uniform concrete surface is called ____________
Explanation: The levelling operation that removes humps and hollows and give a true, uniform concrete surface is called Screeding.
4. What is the limitation of plasticizers?
a) A good plasticizer is one which does not cause air-entrainment in concrete > .1-.2%
b) A good plasticizer is one which does not cause air-entrainment in concrete > 5%
c) A good plasticizer is one which does not cause air-entrainment in concrete > 10-20%
d) A good plasticizer is one which does not cause air-entrainment in concrete > 1-2%
Explanation: A good plasticizer is one which does not cause air-entrainment in concrete is greater than 1-2%.
5. What is the allowed reduction of water with super plasticizers without reducing workability.
Explanation: Super plasticizers permits reduction of water content about 30% without reducing the workability.
6. A lower ratio leads to ___
a) Higher strength and durability
b) Higher strength but low durability
c) Lower strength but high durability
d) Lower strength and durability
Explanation: A lover ratio leads to higher strength and durability, but may make the mixture difficult to work.
7. Silica fume is _________
a) Less reactive
c) More reactive
d) Absent in concrete
Explanation: One of the most beneficial uses for silica fume is in concrete, because of its both properties, it is a very reactive pozzolana.
8. Content of SiO2 in silica fume?
Explanation: The content of SiO2 in silica fume is 85-97%. 35% is the content of SiO2 in Calcareous (ASTM C618 Class C) Fly Ash.
9. What is the content of Al2O3 in fly ash?
c) Up to 30%
Explanation: The content of 2O3 in fly ash has been tested according to procedures specified in IS: 1727-1967.
10. Find the odd one out.
a) Water reducing plasticizers
b) Water reducing plasticizers
c) High performance plasticizers
d) Super plasticizers
Explanation: Water reducing plasticizers, Water reducing plasticizers, High performance plasticizers are the types of plasticizers available in India.
Sanfoundry Global Education & Learning Series – Concrete Technology.
To practice MCQs on all areas of Concrete Technology, here is complete set of 1000+ Multiple Choice Questions and Answers.