For complete hydration of Portland cement, the total water required as a percentage of cement weight is approximately:
A{'text': 'About 23 percent', 'label': 'A'}
B{'text': 'About 30 percent', 'label': 'B'}
C{'text': 'About 38 percent', 'label': 'C'}
D{'text': 'About 50 percent', 'label': 'D'}
Answer & Solution
Correct answer: C. {'text': 'About 38 percent', 'label': 'C'}
1. §1.6.1 (after Figure 1.3): bound water is 23 percent and gel-pore water is about 15 percent, so 'a total of 38 percent of water by weight of cement is required for complete hydration and to occupy the space within the gel-pores.'
2. Adding more than 38 percent leaves capillary cavities and weakens the concrete.
_Source: IGNOU ET-522 Block-1 Unit-1 Cement, §1.6.1, p. 10_
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