This set of Repair and Rehabilitation of Structures Multiple Choice Questions & Answers (MCQs) focuses on “Techniques for Repairing Cracks”.
1. Periodic observation of cracks is done using telltales.
a) True
b) False
View Answer
Explanation: In order to repair the cracks, the nature of the cracks (i.e.) whether it is active or dormant must be determined. For accomplishing this, cracks are observed periodically to determine their nature and are done using the telltales.
2. While using telltales the marking is placed at the ________ of the crack.
a) middle
b) start
c) end
d) top
View Answer
Explanation: Usually the marks are placed at the end of the crack while using telltales to identify the growth of the cracks by which the nature of the crack is determined and also sometimes a pin or toothpick is slightly wedged into the crack and it falls when if there is any extension of the defect.
3. When notched tape is used the movement is indicated by _______ of the tape.
a) tearing
b) falling
c) compression
d) breaking
View Answer
Explanation: The notch tape is placed at the end of the crack and when the cracks starts to increase in length, the tape is torn which indicates the movement of the crack and the cracks is determined to be an active crack. If the tearing of the tape is not found then the crack is a dormant crack.
4. Which of the following device is used when accurate readings of the cracks are desired?
a) Telltales
b) Strain gauges
c) Extensometer
d) Vernier caliper
View Answer
Explanation: When accurate reading about the cracks is needed the extensometer is used because they give accurate reading about the dimensions of the crack when compared with other devices and also they provide stress strain measurements of the cracks.
5. Cracks in the concrete are bonded by the injection of ______ bonding components under pressure.
a) epoxy
b) ether
c) acetylene
d) resin
View Answer
Explanation: Usually the cracks in the concrete are bonded by injecting epoxy bonding components under pressure through holes about \(\frac{3}{4}\) inches in diameter and \(\frac{3}{4}\) inch deep at 6 to 12 inches center as these epoxy components have good bonding and adhesive properties than any other components.
6. Which of the following methods involves enlarging the crack along their exposed surface and filling them suitable material?
a) Epoxy injection
b) Routing and sealing
c) Stitching
d) External stressing
View Answer
Explanation: Routing and sealing method, the exposed surface of the crack is enlarged and is filled with suitable sealant material according to the nature of the cracks and this technique is mainly adopted thorough water tightness of the joint is not required and also in places where appearance is not needed.
7. In stitching technique, the concrete cracks are sealed using _______
a) steel dogs
b) copper dogs
c) aluminum dogs
d) bonze dogs
View Answer
Explanation: The stitching on the concrete cracks is made on the side which is opening first with the help of steel dogs that are bent into the broad flattened letter U shape which seals the cracks.
8. The dogs used for stitching are of uniform length and orientation.
a) True
b) False
View Answer
Explanation: The dogs that are used for stitching are of variable length and orientation so the tension that is transmitted across the crack doesn’t revolve around a single plane but it is spread over the adjacent areas there by strengthening the adjacent areas.
9. In order to provide resistance to the shear along the crack _________ stitching is preferred.
a) shear
b) diagonal
c) horizontal
d) vertical
View Answer
Explanation: For providing resistance to the shear that is developed along the crack usually diagonal stitching is provided in a random manner so that the anchor points don’t form a plane of weakness.
10. When cracks are repaired using eternal stressing the cracks are closed by inducing compressive force.
a) True
b) False
View Answer
Explanation: When the cracks are closed by inducing compressive force the width of the cracks gets smaller thereby sealing the cracks and also this compression force facilitates residual compression.
Sanfoundry Global Education & Learning Series – Repair and Rehabilitation of Structures.
To practice all areas of Repair and Rehabilitation of Structures, here is complete set of Multiple Choice Questions and Answers.
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