141. Alkali-Silica reactivity is a potential cause of distress in
- sludge treatment plant
- hydraulic jump
- concrete
- drinking water
142. Which of the following is present in the highest percentage in coal fly ash suitable to be used in concrete?
- Aluminium oxide
- Silicon oxide
- Calcium oxide
- Magnesium oxide
143. Which of the following parameters is critical in designing cement concrete mix exposed to repeated freeze-thaw?
- Water reducer
- Accelerator
- Entrained air
- Excess cement
144. A concrete pour of 1080 m3 is planned with a 120 m3/hr capacity. If the efficiency of the plant is assumed to 75%, what will be approximate time taken for completing the pour?
- 8
- 9
- 7.5
- 12
145. The batching accuracy (in %) of water used for mixing concrete should be within
- ± 2
- ± 1
- ± 5
- ± 3
146. In shotcreting, what is the purpose of accelerating chemical?
- to adjust the workability of shotcrete
- to accelerate the initial strength gain
- to provide better finish to shotcrete
- to improve the bonding between substrate and shotcrete
147. The strength and quality of concrete depends on
- aggregate shape
- aggregate grading
- surface area of the aggregate
- all of the above
148. The lower water cement-ratio in concrete produces
- more density
- small creep and shrinkage
- more bond
- all of the above
149. The strength of concrete is directly proportional to
- water cement ratio
- cement water ratio
- sand cement ratio
- water aggregate ratio
150. Identify the corresponds to accelerator : retarder.
- NaOH : KOH
- CaCl2 : CaSO4
- KOH : NaOH
- NaCl : CaCl2