Aggregate

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Aggregate

What is Aggregate?

Aggregate: Granular material such as sand, gravel, or crushed stone used in concrete, asphalt, and base courses.

Description

Aggregate is a commonly used term in the construction industry. Aggregate refers to sand, gravel, crushed stone, or slag that forms the bulk of concrete, asphalt, and road base. Classified as fine (≤ 4.75 mm) or coarse (> 4.75 mm), aggregates occupy up to 75 % of concrete volume, providing compressive strength and dimensional stability. Gradation, cleanliness, and hardness directly affect workability, strength, and durability of mixes. Aggregates are sourced from natural pits or quarries and tested for deleterious materials, abrasion resistance, and absorption.

FAQs

  • Why is aggregate important in concrete?

    It provides strength, volume, and reduces shrinkage.

  • What is the difference between coarse and fine aggregate?

    Particle size—coarse is larger than 4.75 mm; fine is smaller.

  • How is aggregate quality tested?

    ASTM C33 covers grading, impurities, and soundness requirements.

  • Can recycled concrete be used as aggregate?

    Yes—processed RCA (recycled concrete aggregate) is common in road base.

  • What is gap-graded aggregate?

    A blend missing intermediate sizes, used for stone matrix asphalt.

  • Does aggregate affect concrete color?

    Yes—exposed aggregate finishes reveal natural stone hues.

  • Who supplies aggregates?

    Quarry operators and sand & gravel producers deliver by truck or rail.

Fun Fact

Fun Fact: The world’s largest open‑pit aggregate quarry, Thornton Quarry in Illinois, spans nearly 1.5 by 1 mile and supplies Chicago’s construction market.

Links

CSI Code

03 05 00

NAHB Code

330