Per §5.3.4, rounded aggregates produce more workable concrete than ang…

Question

Per §5.3.4, rounded aggregates produce more workable concrete than angular or flaky aggregates principally because:

Accepted Answer

C. {'text': 'Rounded grains act like ball bearings and reduce internal friction in the mix', 'label': 'C'}

1. §5.3.4: 'The rounded shape also acts as ball bearing and reduces internal friction.' For a given volume rounded aggregates have less surface area and fewer voids than angular or flaky aggregates.
2. This is why river sand and gravel give better workability than crushed sand and aggregate.
_Source: IGNOU ET-522 Block-2 Unit-5 Workability & Fresh Concrete-I, §5.3.4, p. 7_

Answer

{'text': 'The Portland cement reacts chemically in a different way with rounded grains', 'label': 'A'}

Answer

{'text': 'Rounded grains permanently absorb noticeably less mixing water than crushed types', 'label': 'B'}

Answer

{'text': 'Rounded grains in the mix carry a measurably higher specific gravity than angular ones', 'label': 'D'}