Irrigation Engineering Questions and Answers – Joints Provision and Water Bars in RCC Ducts of Aqueducts

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This set of Irrigation Engineering Questions and Answers for Campus interviews focuses on “Joints Provision and Water Bars in RCC Ducts of Aqueducts”.

1. Which of the following is usually adopted for contraction and construction joints?
a) Rubber water bars
b) V-shape metal bars
c) PVC water bars
d) Z-shape metal bars
View Answer

Answer: c
Explanation: Metal water stops (both V-shape and Z-shape) and rubber water stops are used in ducts of aqueducts and super-passages in expansion joints. PVC water stops are generally adopted for Construction and contraction joints of aqueducts and super-passages.
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2. Which of the following is not a movement joint?
a) Contraction joint
b) Expansion joint
c) Sliding joint
d) Construction joints
View Answer

Answer: d
Explanation: The various types of joints involved in RCC constructions are divided into the movement joints and the construction joints. The movement joint includes contraction joints, expansion joints, and sliding joints.

3. A partial contraction joint is the one in which?
a) both the concrete and reinforcing steel are interrupted
b) only the concrete is interrupted
c) only the reinforcement is interrupted
d) none of them is interrupted
View Answer

Answer: b
Explanation: A complete contraction joint is the one in which both the concrete and reinforcing steel is interrupted. A partial contraction is the one in which only the concrete is interrupted the reinforcing steel running through. A distinction should also be made between them.

4. Which of the following is a movement joint with deliberate discontinuity but no initial gap?
a) Contraction joint
b) Expansion joint
c) Sliding joint
d) Construction joints
View Answer

Answer: a
Explanation: A joint which has no initial gap between the concrete on either side of the joint with a deliberate discontinuity and the joint being intended to accommodate contraction of concrete is called a construction joint. Expansion joint and Sliding joints are movement joints and there is a complete discontinuity in both the reinforcement and concrete.

5. Which of the following is a movement joint with complete discontinuity in both reinforcement and concrete and intended to accommodate either expansion or contraction of the structure?
a) Contraction joint
b) Expansion joint
c) Sliding joint
d) Construction joints
View Answer

Answer: b
Explanation: Expansion joint includes the provision of an initial gap which by opening or closing accommodates the expansion or contraction of the structure. It is sometimes advantageous to incorporate sliding surfaces for the design of the joint.

6. In reinforced concrete floors, the movement joints should normally be spaced at a maximum spacing of ____________
a) 6 m
b) 4.5 m
c) 7.5 m
d) 9 m
View Answer

Answer: c
Explanation: The concrete floor should be cast in panels with sides not more than 4.5 m in case of floors with a nominal percentage of reinforcement. The movement joints should be placed at a maximum spacing of 7.5 m for reinforced floors in two directions at right angles.
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7. The expansion joints in floors and walls should normally be provided at a spacing of not more than ___________
a) 30 m
b) 45 m
c) 50 m
d) 55 m
View Answer

Answer: a
Explanation: The maximum spacing of 30 m is provided between successive expansion joints or between the ends of the structure. The provision of movement joints in each element can be considered independently where sliding joints are provided between walls and either the floor or roof.

8. What is the maximum expansion or contraction allowed for the joint filler material with an initial gap of about 30 mm?
a) 10 mm
b) 5 mm
c) 20 mm
d) 30 mm
View Answer

Answer: a
Explanation: Joint fillers are normally compressible sheets or strip materials that are used as spacers and they are fixed to the face of first placed concrete. The maximum permissible expansion or contraction is of the order of 10 mm.

9. Which of the following can be used as support for an effective joint sealing compound in floor and floor joints?
a) Joint fillers
b) Water bars
c) Joint sealers
d) Primers
View Answer

Answer: a
Explanation: Joint fillers cannot function as water-tight expansion joints by themselves and they can be used as support for an effective joint sealing compound. The gap provided in the joint is being bridged by a water bar.

10. What provides a permanent watertight seal during the whole range of joint movement?
a) Water bars
b) Joint fillers
c) Joint covers plates
d) Joint sealers
View Answer

Answer: a
Explanation: These are the preformed strips of impermeable materials which are embedded in concrete during construction. It spans across the joint and provided watertight seal during joint movement. It is important to ensure proper compaction of the concrete with all water bars for the same purpose.

11. Which of the following is sometimes used in expansion joints to avoid the risk of fault in an embedded water bar?
a) Joint fillers
b) Joint sealers
c) Joint covers plates
d) Water stops
View Answer

Answer: c
Explanation: Joint cover plates are sometimes used in expansion joints and it may be of copper or sheet lead. It should be clamped to the concrete face on each side of the joint using suitable gaskets to ensure water tightness in case of the copper cover plate. In sheet lead, lead caulking is done to make it completely water-tight.

12. Joint sealing compounds are impermeable ductile materials which are required to ___________________
a) increase the bond
b) provide a watertight seal by adhesion to concrete
c) shorten the water path
d) avoid the risk of a fault in an embedded water bar
View Answer

Answer: b
Explanation: They are impermeable ductile materials and commonly used materials are based on asphalt, bitumen or coal tar with or without fillers. These are required to provide a water-tight seal by adhesion to the concrete. Water bars are used to increase the bond and shorten the water path.
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13. In case of the sealing joint, the lower part of the joint is occupied by joint filler.
a) True
b) False
View Answer

Answer: b
Explanation: The lower part is occupied by joint filler in case of the expansion joints. Since the retention of the material is assisted by gravity and sealing can be delayed until just before the reservoir is put in to service this type of joint is quite successful.

14. What is the most common metal used for water stops?
a) Monel metal
b) Annealed copper
c) Galvanised iron
d) Steel
View Answer

Answer: b
Explanation: When the thickness is not less than 1.5 mm, annealed copper is the most common metal used for water stops but it is likely to get brittle with time and may then crack. Sometimes galvanized iron or steel strips are also used though Monel metal is considered more durable.

15. The use of sealing compounds for vertical joints is very successful.
a) True
b) False
View Answer

Answer: b
Explanation: The use of sealing compounds is not very successful for vertical joints. A stepped joint with a water bar incorporated in the joint and sealing compound packed round the corrugation of the water would be much more successful instead of straight through-joint.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn