5.14 : 骨材の嵩密度

The bulk density of aggregates indicates the mass of aggregates within a unit volume, including the void spaces existing among them. It is generally expressed in pounds per cubic foot.

Aggregates that are compacted densely achieve a higher bulk density compared to aggregates that are compacted loosely.

When aggregates of different sizes are compacted, the smaller particles fill the gaps between the larger particles, resulting in a higher bulk density than when compacting aggregates of similar sizes.

Additionally, the shape of aggregates also influences their bulk density. Rounded aggregates pack with fewer voids than angular ones, thereby contributing to higher bulk density of rounded aggregates.

Also, the existence of moisture on the surface of aggregates pushes the adjacent aggregates apart which hinders its dense packing.

The percentage of void spaces is calculated using the bulk density of the aggregate, the bulk specific gravity in the saturated surface-dry state of aggregate, and the unit mass of water.

The amount of void spaces indicates the volume of mortar required to fill the gaps between the coarse aggregates in the concrete mix.