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One kilogram of ice absorbs about 334 kJ when it changes phase to water at 0 °C. This makes ice attractive for cooling concrete because:
Answer & Solution
Correct answer: C.
1. Sensible cooling by chilled water is limited by how cold the water can get and how much can be added.
2. Replacing part of the mixing water with ice harvests the 334 kJ per kg latent heat of fusion as well.
3. The unit calls ice one of the basic methods of lowering concrete placing temperatures for this reason.
4. All of the ice must melt before mixing completes so the concrete remains homogeneous.
5. Cost, expansion and segregation are not the reasons the unit gives.
_Source: IGNOU Concrete Technology, Unit 7 "Concreting Equipment" (Mixers, Cableways, Batchers, Buckets, Pre/Post Cooling)._
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