Per §3.3.2, which of the following salts in mixing water is described as 'completely destructive' to concrete strength?
- Sodium iodate
- Lead nitrate
- Zinc chloride
- Sodium carbonate
Show answer and solution
Correct answer: B. Lead nitrate
1. §3.3.2 reads: 'The effect of lead nitrate is completely destructive.'
2. Zinc chlorides retard set, sodium carbonate may cause quick setting, sodium iodate reduces initial strength — but none are described as completely destructive.
_Source: IGNOU ET-522 Block-1 Unit-3 Water, §3.3.2, p. 42_