Understanding the Essential Characteristics of Aggregates in Concrete Production

Aggregates are vital components in the creation of concrete, serving as inert granular materials that include gravel, crushed stone, sand, slag, recycled concrete, and geosynthetic aggregates. They can be natural, manufactured, or recycled, influencing the overall quality and performance of concrete. In this discussion, we delve into the physical requirements of aggregates, focusing on parameters such as resistance to fragmentation, wear, polishing, abrasion, particle density, bulk density, and durability, as outlined by European Standards (EN – 12620).

1. Resistance to Fragmentation of Coarse Aggregate:

To assess the resistance to fragmentation, the Los Angeles test method is employed, measuring the Los Angeles coefficient. The obtained coefficient is categorized according to specific applications, as detailed in Table 12. Impact values are also considered and categorized based on Table 13.

2. Resistance to Wear of Coarse Aggregate:

The resistance to wear is determined through the micro-Deval test, with results categorized in Table 14 based on application or end-use.

3. Resistance to Polishing:

For aggregates used in surface courses, the polished stone value (PSV) is assessed and categorized as per Table 15.

4. Resistance to Surface Abrasion:

Surface abrasion resistance (aggregate abrasion value – AAV) is determined and categorized according to Table 16.

5. Resistance to Abrasion from Studded Tires:

The abrasion resistance from studded tires (Nordic abrasion value – An) is evaluated and categorized based on Table 17.

6. Particle Density and Water Absorption:

Particle density and water absorption are measured according to EN 1097-6, with results provided on request.

7. Bulk Density:

Bulk density is determined in accordance with EN 1097-3, with results available on request.

8. Durability:

Durability is assessed through various tests, including freeze and thaw resistance, volume stability (drying shrinkage), and alkali-silica reactivity.

Understanding the Significance of Aggregates in Concrete: The properties of concrete, encompassing workability, durability, strength, weight, and shrinkage, are intricately tied to the characteristics of the aggregate used.

Common Coarse Aggregate Size in Concrete Production: Typically, aggregates passing a 20mm sieve and retained on a 12.5mm sieve are preferred for concrete production.