Measuring the particle shape of aggregates for bituminous and cement concrete types

The particle shape of aggregates is determined by the percentages of flat (flakiness) and elongated particles it contains. For bituminous and cement concrete types, the presence of flat and elongated particles is considered undesirable, because it (negatively) influences the properties of mixtures.

When the proportion of flat particles in hydraulic concrete increases, the compressive strength decreases, the cement consumption increases and the workability decreases. It creates weak concrete, which can lead to breaking when overloaded. This also applies to bituminous mixtures, such as, for example, asphalt; an increase in the flat particles causes a reduction in compactness and the reduction in compressive and tensile strength. Therefore, evaluation of the shape of the particles, in particular with regard to flatness and length, is necessary.