Correct Answer - Option 3 : Angular aggregates
Concept:
Aggregates are the important constituents of the concrete which give body to the concrete and also reduce shrinkage. Aggregates occupy 70 to 80 % of total volume of concrete.
Aggregates are classified on the basis of shape, texture, size, and grading
Classification of aggregates on basis of shape –
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Rounded aggregates / spherical - Rounded aggregates result the minimum percentage of voids (32 – 33%) hence gives more workability. They require lesser amount of water-cement ratio. They are not considered for high strength concrete because of poor interlocking behaviour and weak bond strength.
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Irregular or partly rounded aggregates - Irregular aggregates may result 35- 37% of voids. These will give lesser workability when compared to rounded aggregates.
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Angular aggregates - Angular aggregates result maximum percentage of voids (38-45%) hence gives less workability and high strength due to interlocking.
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Flaky aggregates - When the aggregate thickness is small when compared with width and length of that aggregate it is said to be flaky aggregate. Or in the other, when the least dimension of aggregate is less than the 60% of its mean dimension then it is said to be flaky aggregate.
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Elongated aggregates - When the length of aggregate is larger than the other two dimensions then it is called elongated aggregate or the length of aggregate is greater than 180% of its mean dimension.
