Which properties of concrete are affected by flaky aggregates?

Concrete produced using flaky and elongated aggregates will be prone to segregation, poor surface finish, high cement and sand demand.

How the shape flakiness and elongation of the aggregate can affect the strength towards pavement?

Flaky and elongated particles have larger specific surface area, which results in higher demand of cement paste in cement concrete mix. These particles impede compaction or break during rolling and decrease the strength of pavement layer.

Why flaky and elongated aggregates are not preferred in construction?

Due to high surface area to volume ratio, the flaky and elongated particles lower the workability of concrete mixes. Flaky and elongated particles are considered undesirable for base coarse construction as they may cause weakness with possibilities of braking down under heavy loads.

What is the difference between flakiness and elongation of aggregate?

The Flakiness Index of aggregates is the percentage by weight of particles whose least dimension (thickness) is less than 0.6 times their mean dimension. The Elongation Index of aggregates is the percentage by weight of particles whose greatest dimension (length) is greater than 1.8 times their mean dimension.

What are the disadvantages of using flaky and elongated aggregates?

Flaky and elongated aggregates can adversely affect concrete. Flaky and elongated aggregates are difficult to compact. Therefore using flaky and elongated aggregates will reduce concrete workability, which required more amount of water to produce a workable mix. Increasing water content will reduce concrete strength and durability.

How does the shape of aggregate affect the strength of concrete?

The full role of shape and texture of aggregate in the development of concrete strength is not known, but possibly a rougher texture results in a larger adhesive force between the particles and the cement matrix. Likewise, the larger surface area of angular aggregate means that a larger adhesive force can be developed.

What is the flakiness index of aggregates?

The Flakiness Index of aggregates is the percentage by weight of particles whose least dimension (thickness) is less than three- fifths (0.6times) of their mean dimension.

What is the importance of particle shape in concrete grading?

In addition to the aggregate grading, the particle shape is of importancefla. The usual shapes of the particles are; Rounded (river gravel) improves the workability of concrete due to the less friction between the surfaces. 2. Irregular having rounded edges. 2. Flaky considered as a source of weakness.

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