Civil Engineering Paper
1.Which of the following statements are wholly correct regarding broken-brick aggregate useable in concretes?
1. Broken-brick aggregate is obtained by crushing waste bricks; and it has a density varying between 1000 kg/m3 – 1200 kg/m3.
2. Such aggregate is usable in concrete for foundation in light buildings, floorings and walkways.
3. Such aggregate may also be used in light-weight reinforced concrete floors.
1 and 2 only
2 and 3 only
1 and 3 only
1, 2 and 3
2. In handling air-entraining admixtures the beneficial amount of entrained air depends upon certain factors like
1. Type and quantity of air-entraining agent
2. Water-cement ratio of the mix
3. Strength of aggregates
4. Extent of compaction of concrete
(a) 1, 2 and 3 only
(b) 1, 2 and 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4
Which one of the following statements is not correct with respect to fly ash?
(a) As part replaceinent of cement in the range of 15% – 30%, fly ash reduces the strength in the initial period, but once the Pozzolanic process sets in, higher strength can be obtained.
(b) Fly ash as a part replacement of sand has a beneficial effect on strength even at early age.
(c) Fly ash as a part replacement of sand is economical.
(d) A simultaneous replacement of cement and fine aggregates enables the strength at a specified age to be equalled depending upon the water content.
4. Which one of the following statements is not correct with respect to the properties of cement?
(a) Highly reactive Pozzolanas enhance the early age strength of the composite cement.
(b) Pozzolanic activity refines pore structure which decreases electrolytic resistance of concrete.
(c) The expansion due to alkali-silica reaction can be controlled by replacement of as high as 60% of OPC with high-calcium Pozzolana.
(d) Such high amounts of replacement cements result in higher accelerated carbonation depths compared to pure use of OPC only
5. Hydration of which compound is responsible for increase in strength of cement in later age?
(a) Tr-calcium Aluminate (C3A)
(b) Tetra-calcium Alummoferrite (C4AF)
(c) Tr-calcium Silicate (C35)
(d) Di-calcium Silicate (C25)
6. The creep strain of cement attains its terminal value by
(a) 1 year
(b) 2 years
(c) 5 years
(d) 6 months
7. Which of the following methods will help in reducing segregation in concrete?
1. Not using vibrator to spread the concrete
2. Reducing the continued vibration
3. Improving the cohesion of a lean dry mix through addition of a further small quantity of water
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 and 3 only
(d) 2 and 3 only
8. On an average, in a 125 mm slump, the concrete may lose about (in first one hour)
(a) 15 mm of slump
(b) 25 mm of slump
(c) 40 mm of slump
(d) 50 mm of slump
9. Permeability in concrete is studied towards providing for, or guarding against, which of the following features?
1. The penetration by materials in solution may adversely affect the durability of concrete; moreover, aggressive liquids ‘attack’ the concrete.
2. In case of reinforced concrete, ingress of moisture and air will result in corrosion of steel leading to an increase in volume of steel, resulting in cracking and swilling of the concrete cover.
3. The moisture penetration depends on permeability and if the concrete can become saturated with water it is less vulnerable to frost action.
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 and 3 only
(d) 2 and 3 only
10. Which one of the following methods/techniques will be used for placing of concrete in dewatered ‘Caissons or Coffer’ dams?
(a) Tremie method
(b) Placing in bags
(c) Prepacked concrete
(d0 In-the-dry practice