Per §5.3.7, the air-entraining agent increases the workability of fres…

Question

Per §5.3.7, the air-entraining agent increases the workability of fresh concrete by acting:

Accepted Answer

B. {'text': 'As a surface-active agent that reduces internal friction (bubbles act as ball bearings)', 'label': 'B'}

1. §5.3.7: 'The air-entraining agent being surface active, reduces the internal friction between the particles. The air bubbles can be viewed to act as ball bearings, enabling the particles to slide past each other, thus increasing mobility.'
2. Pozzolanic materials likewise add lubricating effect.
_Source: IGNOU ET-522 Block-2 Unit-5 Workability & Fresh Concrete-I, §5.3.7, p. 7_

Answer

{'text': 'As a strong chemical retarder of the Portland cement setting reaction in the early hours', 'label': 'A'}

Answer

{'text': 'By substantially raising the specific gravity of the mix and so improving overall flow', 'label': 'C'}

Answer

{'text': 'By forming a continuous watertight crust on the upper concrete surface during placing', 'label': 'D'}