Name: how aggregate size affects bulk density
Uploaded: 2024-09-12T16:16:40.000Z
Duration: 1 min 22 s
Channel: JoVE

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.

bulkdichtheid van aggregaat

Bulkdichtheid verwijst naar de massa van aggregaat deeltjes die een eenheid volume zouden vullen. Het concept van bulkdichtheid is ontstaan ​​door het onvermogen om aggregaat deeltjes op een manier te verpakken die lege ruimtes volledig elimineert. Daarom verwijst de term bulk naar het volume dat zowel de aggregaten als de lege ruimtes omvat. Deze meting is cruciaal wanneer aggregaten op volume worden gegroepeerd en wordt gebruikt om hoeveelheden van massa naar volume om te zetten.

De meeste natuurlijke minerale aggregaten, zoals zand en grind, vertonen doorgaans een bulkdichtheid van 1.521,75 tot 1.601,85 kg/m^3 en worden gebruikt om beton van normaal gewicht te produceren met een eenheidsgewicht van ongeveer 2.402,77 kg/m^3.. Aggregaten met een bulkdichtheid van minder dan 1.121,29 kg/m^3 worden geclassificeerd als lichtgewicht, terwijl die met een dichtheid van meer dan 3,68 m^3 als zwaargewicht worden beschouwd.

De bulkdichtheid van aggregaat deeltjes wordt beïnvloed door hun grootteverdeling; Hoewel aggregaten van één grootte slechts in beperkte mate kunnen worden gecompacteerd, kan het introduceren van kleinere deeltjes in de openingen tussen grotere de bulkdichtheid verhogen. De optimale bulkdichtheid van een mix van fijne en grove aggregaten wordt bereikt wanneer fijne aggregaten ongeveer 35 tot 40 procent van de totale aggregaat massa uitmaken.

Bulkdichtheid van aggregaat

The bulk density of aggregates indicates the mass of aggregates within a unit volume, including the void spaces existing among them. It is generally ...

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Civil Engineering

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Unit 1

Aggregates and Water

Aggregaten en water

KEY TERMS AND CONCEPTS

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Bulk Density of Aggregate

how aggregate size affects bulk density

Bulk density describes the mass of aggregate that fills a unit volume, including the empty spaces between particles. Those void spaces remain because aggregate particles cannot be packed so tightly that every gap disappears. In practice, bulk refers to the total volume of both the particles and the spaces around them.

This measurement matters when aggregates are batched by volume. It also helps convert materials measured by mass into a volume-based quantity. Natural mineral aggregates such as sand and gravel usually have a bulk density of about 95 to 100 lb/ft 3, and they are commonly used to make normal-weight concrete with a unit weight of about 150 lb/ft 3.

Aggregates can also be grouped by bulk density. Materials below 70 lb/ft 3 are classified as lightweight. Materials above 130 ft 3 are considered heavyweight.

Particle size distribution changes bulk density. Aggregates made of one size can only be compacted to a limited degree. When smaller particles fit into the gaps between larger ones, the bulk density increases. The best bulk density in a mix of fine and coarse aggregates is reached when fine aggregates make up about 35 to 40 percent of the total aggregate mass.

How Aggregate Size Affects Bulk Density

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JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

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How Aggregate Size Affects Bulk Density

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