This set of Basic Construction Materials Questions and Answers focuses on “Curing of Concrete”.
1. The process of Rolling, folding and spreading of particle is known as the __________ of concrete.
Explanation: The materials of concrete should be mixed thoroughly so that there is a uniform distribution of materials in the mass of concrete. The thorough mixing also ensures that water cement paste completely covered the surface of aggregate.
2. For _______ mixing, the materials are stacked on watertight platform, which may be either of wood, Brick or steel.
Explanation: The mixing by hand is allowed in case of small works on unimportant work were small quantity of concrete is required. For important work, if hand mixing is to be adopted, it is advisable to use 10% more cement than specified.
3. For ________ mixing, all the material of concrete including water, are collected in a revolving drum and drummer is rotated for a certain period.
Explanation: It is found that the materials of concrete with the help of machine is more efficient and it produces concrete of better quality in a short time. The mixtures of various types and capacities are available in the market. They are may either be of tilting type or non tilting type.
4. For ordinary building works, the ___________ is formed and the concrete is conveyed in pans from hand to hand.
a) Conveyor belt
c) Human ladder
Explanation: The type of equipment to be used for transport of concrete depends on the nature of work, height above the ground level and the distance between the points of preparation and placing of concrete. For important words, the various mechanical devices such as a dumpers, truck mixer, conveyor belts, etc. may be used.
5. The term ________ of concrete is used to mean the compaction between aggregate and aggregate; between aggregate and reinforcement and between aggregate and forms.
Explanation: The main aim of consolidation of concrete is to eliminate air Bubbles and thus to give maximum density to the concrete. The importance of consolidation of concrete can be seen from the fact that a presence of 5% of voids reduce 30% strength of concrete.
6. The ________ are the gaps between two individual particles.
Explanation: The difference between voids and pores may be noted. The pores represent the opening within the individual particles. The process of consolidation of concrete can be carried out either by hand or by means of vibrators.
7. Form unimportant works, the consolidation of concrete is carried out by ______ method which include Ramming, tamping, spading and slicing with suitable tools.
Explanation: The Hand Method require use of a fairly wet concrete. It should however be remembered that wherever feasible, the hand competition should be preferred because the use of vibrator may lead to the segregation of the aggregates.
8. _________ vibrators consists of the Steel Tube which is inserted in a fresh concrete.
a) Surface vibrators
b) Internal vibrators
c) Vibrating table
d) Shutter vibrators
Explanation: The Internal vibrators or Immersion vibrators should be inserted and withdrawn slowly and they should be operated continuously while they are being withdrawn. In this, the Steel Tube is called poker and it is connected to an electric motor or a petrol engine through a flexible tube.
9. _________ vibrators are mounted on platforms or screeds.
a) Form vibrators
b) Surface vibrators
c) Shutter vibrators
d) Immersion vibrators
Explanation: Surface vibrators are used to finish concrete surface as a bridge floors, roads slabs, station platform, etc. These vibrators are found to be more effective for compacting very dry concrete mixes because the vibration acts in the same direction of gravity and the concrete is compacted in the confined zone.
10. __________ vibrators are attached to the form work and the external centring of walls, column, etc.
a) Shutter vibrators
b) Surface vibrators
c) Internal vibrators
d) Immersion vibrators
Explanation: In Form or Shutter vibrators, the Vibrating action is conveyed to concrete through the formwork. A considerable energy is absorbed by the formwork during transmission of vibration. Hence they are not generally used.
Sanfoundry Global Education & Learning Series – Construction and Building Materials.
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