Quiz: Civil Engineering
Exam: DFCCIL EXECUTIVE
Topic: CONCRETE TECHNOLOGY
Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes
Q1. Workability of concrete can be improved by
(a) Increasing flaky aggregate
(b) Decreasing coarse aggregate
(c) Increasing fine aggregate
(d) Increasing size of aggregate
Q2. The process of mixing some mortar in the mixer at the beginning of the first batch concrete mixing is called:
(d)None of these
Q3. The concrete cubes are prepared, cured and tested according to Indian standards code number
(a) IS: 515
(b) IS: 516
(c) IS: 517
(d) IS: 518
Q4. The percentage of the fine aggregate of fineness modulus 2.6 to be combined with coarse aggregate of fineness modulus 6.8 for obtaining the aggregates of fineness modulus 5.4, is:
Q5. Under normal conditions using ordinary cement, the period of removal of the form work, is
(a) 7 days for beam soffits
(b) 14 days for bottom slabs of spans 4.6 m and more
(c) 21 days for bottom beams over 6 m spans
(d) all options are correct
Q6. Under water concreting is done by:
(a) Dripping method
(b) Tremie method
(c) Cofferdam method
(d)All of the above
Q7. Concrete is unsuitable for compaction by a vibrator if it is………..
(b) earth moist
Q8. Compaction of concrete helps in
(a) segregation of aggregates
(b) Removal of excess water
(c) increase of density
(d)addition of required air voids
(a) Reduces the shrinkage of concrete
(b) Preserves the properties of concrete
(c) prevents the loss of water by evaporation
(d) All option are correct
Q10. The resistance of aggregate to wear is known as
(a) impact value
(b) abrasion resistance
(c) shear resistance
(d) crushing resistance
Sol. Workability of concrete is directly proportional to the size of aggregate. As increase in the size of aggregate, workability of concrete is also increased.
Sol. Buttering is the process of mixing some mortar in the mixer at the beginning of the first batch concrete mixing.
Sol. According to IS :516, concrete cubes are prepared, cured and tested.
fineness modulus of combine mix(z) = 5.4
fineness modulus of coarse aggregate (x) = 6.8
fineness modulus of fine aggregate (y) = 2.8
Percentage of fine aggregate
p = (x-z)/(z-y)×100=(6.8-5.4)/(5.4-2.8)×100
= 53% ⋍ 50%
Sol. Tremie method is used for under water concreting
Sol. Vibrator is unsuitable for compaction of plastic concrete because it is cohesive in nature.
Sol. compaction of concrete helps in removal of air voids and increase the density and strength of concrete.
Sol. Curing of concrete helps increase the strength of concrete and prevent shrinkage and loss of water by evaporation.
Sol. The resistance of an aggregate to wear is known as abrasion resistance.