Aggregates & Crused stone

The size standards for construction aggregates in China primarily follow GB/T 14685-2022 "Pebble and Crushed Stone for Construction", while the international standards widely referenced are ASTM C33/C33M (United States) and EN 12620 (Europe). There are some differences in their classification and terminology.

Summary of Core Differences

• Terminology:

  1. China Standard (GB/T 14685): Primarily uses the term "crushed stone," classified into continuous grading and single-size grading based on particle size distribution.

  2. International Standards (ASTM/EN): ASTM commonly uses the term Coarse Aggregate. EN also uses Coarse Aggregate but has more detailed categories.

• Typical Size Grading:

  1. China Standard:

     • Continuous Grading: 5-10mm, 5-16mm, 5-20mm, 5-25mm, 5-31.5mm, 5-40mm

     • Single-Size Grading: 10-20mm, 16-31.5mm, 20-40mm, 31.5-63mm, 40-80mm

  2. International Standards:

     • ASTM C33: Uses size numbers like #57 (25-10mm), #67 (25-4.75mm), #8 (12.5-2.36mm), etc., with specific particle size range requirements.

     • EN 12620: Uses D/d notation (e.g., Dmax=20mm, Dmin=10mm) or standard sieve fractions (e.g., Gc 85/20).

• Definition of Maximum Particle Size:

  1. China Standard: Nominal Maximum Size, defined as slightly smaller than the smallest standard sieve size where the cumulative mass percentage retained reaches ≥95%.

  2. ASTM/EN: The concept of Nominal Maximum Size is similar, referring to the first sieve size that allows a small amount of particles (typically <10%) to be larger. The specific definition details vary slightly.

• Particle Shape Requirements:

  1. China Standard: Controlled by limiting the flaky and elongated particle content with specified percentage limits.

  2. ASTM/EN: Also control the content of flaky and elongated particles, but the test methods and limit values may differ. The EN standard has a more detailed classification for particle shape.

• Key Differences:

  1. Grading Systems: The Chinese standard uses intuitive, continuous millimeter ranges for naming. ASTM uses coded "size numbers" that require memorization.

  2. Level of Detail: The European standard EN 12620 provides a more systematic and detailed specification for aggregate properties (e.g., shape, fines content).

  3. Application Orientation: The size grading in international projects (e.g., using ASTM) is often closely tied to specific concrete applications (e.g., paving, structural).

Conclusion: The Chinese standard is highly practical and intuitive for engineering applications. Compared to international standards, the core physical requirements (strength, cleanliness, particle shape) are aligned. The main differences lie in the grading/naming systems and some details of test methods. For international trade or participation in global projects, the key is to convert Chinese specifications to the corresponding ASTM or EN specifications based on the project requirements.

Selecting the appropriate aggregate size is crucial for ensuring project quality and cost-effectiveness.

• Size Type (China Standard): 5-10mm, 5-16mm

  • International Approx. Specs: ASTM: #8, #89; EN: Fine Aggregate / 8-16mm

  • Main Applications:

    1. Precast Concrete Elements: For precast slabs, pipe piles, etc., requiring good flowability and a smooth surface finish.

    2. Architectural Rendering Mortar: Used as an aggregate.

    3. Thin-layer Asphalt Concrete: e.g., for road surface wearing courses.

• Size Type (China Standard): 5-20mm, 5-25mm

  • International Approx. Specs: ASTM: #67, #57; EN: 0/22, 4/22

  • Main Applications:

    1. Commercial Reinforced Concrete: The most commonly used specification for main structural elements like beams, slabs, columns, and walls in buildings.

    2. Prestressed Concrete.

    3. Cement Products.

• Size Type (China Standard): 10-20mm, 16-31.5mm

  • International Approx. Specs: ASTM: #57, #467; EN: 11/22, 16/32

  • Main Applications:

    1. Foundation Concrete: e.g., for large equipment bases, pile caps.

    2. Road Concrete: For pavement layers requiring high flexural strength.

    3. Hydraulic Concrete: (Larger sizes are used for mass concrete).

• Size Type (China Standard): 20-40mm, 31.5-63mm

  • International Approx. Specs: ASTM: #3, #357; EN: 22/45, 32/63

  • Main Applications:

    1. Mass Concrete: e.g., dams, large foundations, where it helps reduce cement content and heat of hydration.

    2. Railway Ballast.

    3. Ground Improvement, Drainage Layers.

• Size Type (China Standard): Stone Chips / Manufactured Sand (0-5mm)

  • International Approx. Specs: ASTM: Fine Aggregate; EN: 0/4, 0/8

  • Main Applications: Serves as Fine Aggregate, mixing with cement and water to form mortar, filling the voids between coarse aggregates, and constituting the complete concrete skeleton.

  • Summary Recommendation:
    When promoting your products, directly link the aggregate size to the customer's specific application scenario. For example, recommend 5-25mm aggregate for commercial housing projects, and 20-40mm or larger sizes for dam projects, explaining the technical reasons behind the choice (such as workability, strength, economy).