The value of the material a quarry produces depends not only on its size but on which application’s standard requirements it meets. Concrete plants, asphalt plants and road and railway projects want to see documents and test reports showing that the aggregate they buy complies with the relevant standards. Understanding the standards allows a production plant to be designed correctly, quality control to be set up correctly and the product to be sold into higher-value markets.
In this guide we give a general overview of aggregate product standards, the category logic they use, the main test standards, and the concepts of conformity assessment and factory production control. Note: Standards are revised periodically; for exact limit values and current versions, refer to the text of the relevant standard in force. This article is for general information.
Main Aggregate Product Standards
| Standard | Scope |
|---|---|
| EN 12620 | Aggregates for concrete |
| EN 13043 | Aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas |
| EN 13242 | Aggregates for unbound and hydraulically bound materials for use in civil engineering work and road construction |
| EN 13450 | Aggregates for railway ballast |
| EN 13139 | Aggregates for mortar |
| EN 13055 | Lightweight aggregates |
| EN 13383 | Armourstone |
These standards define which properties of the product must be determined and which test methods are used to measure them. For most properties, rather than a single limit value, categories are defined; the user (specification or project) chooses the category that suits its needs.
How Does the Category Logic Work?
The basic approach of the European aggregate standards is this: the standard defines the test method for measuring a property and the possible result ranges as categories. The producer declares which category its product falls into. For example, there are different categories for the “Los Angeles coefficient”; a lower LA value means a more durable aggregate. A project may require a lower LA category for a wearing course that needs high resistance, while a wider category may be sufficient for sub-base.
This approach makes it possible to show clearly which applications different products from the same quarry are suitable for.
Main Properties and What They Mean
| Property | What it measures | Production factors that affect it |
|---|---|---|
| Aggregate size (d/D) | The lower and upper sieve sizes of the product | Screen apertures and screening efficiency |
| Grading (particle size distribution) | Particle size distribution by sieve analysis and tolerances | Crusher setting, screening efficiency, stockpile segregation |
| Fines content | Proportion of material below 0.063 mm | Washing, crusher type, clay content |
| Quality of fines (methylene blue, sand equivalent) | Whether the fines contain harmful clay | Quarry selection, washing, hydrocyclones |
| Flakiness index / shape index | Proportion of flat and elongated particles | Crusher type and setting, reduction ratio, use of a VSI |
| Percentage of crushed surfaces | Proportion of crushed particles in gravel aggregates | Degree of crushing of the gravel |
| Los Angeles resistance to fragmentation | Resistance to impact and abrasion | Rock quality |
| Micro-Deval (MDE) | Resistance to wear in wet conditions | Rock quality |
| Polished stone value (PSV) | Retention of skid resistance on the road surface | Rock mineralogy (critical for asphalt wearing courses) |
| Particle density and water absorption | Volume–mass relationship, porosity | Rock type and weathering |
| Freeze-thaw resistance | Durability in cold climates | Rock porosity |
| Chemical properties | Chloride, sulphate, total sulphur, organic matter | Source selection, washing |
| Alkali-silica reactivity | Risk of long-term expansion in concrete | Rock mineralogy |
Main Test Standards
The test methods referred to in the product standards are mainly grouped under the following series:
- EN 932 series: Tests for general properties of aggregates; sampling, sample reduction, petrographic description.
- EN 933 series: Geometrical properties; sieve analysis, flakiness index, shape index, percentage of crushed surfaces, sand equivalent, methylene blue test.
- EN 1097 series: Mechanical and physical properties; Los Angeles, Micro-Deval, density and water absorption, polished stone value.
- EN 1367 series: Thermal and weathering properties; freeze-thaw, magnesium sulphate soundness.
- EN 1744 series: Chemical properties.
The sampling method is critical to the reliability of test results. A sample taken from the surface of a stockpile may not represent the whole product because of segregation (stockpile management).
Key Properties by Application
| Application | Key properties |
|---|---|
| Concrete aggregate | Grading, fines content and quality, particle shape, water absorption, chemical properties, alkali-silica reactivity, freeze-thaw |
| Asphalt wearing course | Los Angeles, polished stone value (PSV), flakiness, crushed surfaces, adhesion to bitumen |
| Asphalt binder and base courses | Grading, LA, particle shape |
| Unbound road layers (sub-base, base) | Grading, fines content and quality, LA, Micro-Deval |
| Railway ballast | Narrow grading, very good particle shape, high resistance to fragmentation and wear, limited fines |
| Mortar aggregate | Fine grading, fines content and quality |
Conformity Assessment and Factory Production Control (FPC)
Because aggregates are classed as construction products, conformity assessment is required when they are placed on the market. In Europe this means CE marking against the relevant harmonised standards; some countries also operate national marking schemes. For aggregates, this process is usually based on certification of the factory production control system by a notified body.
Factory production control (FPC) is the system a producer sets up to ensure that the aggregate it produces continuously meets its declared properties. Typical elements:
- Raw material control and quarry management,
- Control of the production process (crusher settings, screen condition, washing),
- Testing and records at defined frequencies (sieve analysis, fines, etc.),
- Calibrated test equipment,
- Management of non-conforming product,
- Staff competence and documentation.
For current regulations and certification procedures, consult the competent authorities and notified bodies.
The Effect of Plant Design on Compliance
- Grading and particle shape: Crusher type and stage, settings and screening efficiency are decisive. Flakiness problems are usually solved through crusher selection and setting (aggregate quality and particle shape guide).
- Fines: Controlled with washing equipment and hydrocyclones (screw sand washer, hydrocyclone).
- Manufactured sand: Fines content and particle shape are managed with a VSI and sand classification (manufactured sand production).
- Screening efficiency: Worn screen media and overloading lead to out-of-grading product (vibrating screen guide, screen media selection).
- Rock quality: Properties such as LA, MDE and PSV depend on the rock; they cannot be changed by plant design, but can be improved by separating weak zones (rock properties).
Common Mistakes
- Not linking test results with plant settings; seeing the problem only in the laboratory.
- Running screen media until it tears; noticing out-of-grading product too late.
- Taking non-representative samples from stockpiles.
- Sending material from quarry zones of different quality to the same product without separating them.
- Not reflecting the categories in the customer’s specification in the production plan.
A Field Example
Suppose a basalt quarry wanting to enter the asphalt wearing course market finds that its flakiness index does not meet the category in the specification. The rock’s LA and PSV values are suitable; the problem is the secondary cone crusher, running at a high reduction ratio and half-fed. When the reduction ratios are balanced between stages, the cone crusher is run choke fed and a VSI is added at the tertiary stage, the flakiness index falls to the target category. The quarry thus gains access to a higher value-added market.
Frequently Asked Questions
Which standard applies to concrete aggregate?
EN 12620 is the basis for concrete aggregates; the project specification sets the required categories.
Is CE marking mandatory for aggregate?
Conformity assessment is required for aggregates placed on the market as construction products. The details of current regulations and their application should be confirmed with the competent authorities.
How can the flakiness index be reduced?
Crusher type and setting, balancing reduction ratios, choke feeding and shaping with a VSI are the most effective methods.
Can the Los Angeles value be changed by plant settings?
The LA value is essentially a property of the rock; plant settings affect it only to a limited extent. Separating weak zones can improve the result.
Plant-Related Causes of Non-Conforming Product and Related Parts
| Problem | Possible plant cause | Related part / guide |
|---|---|---|
| Excess oversize | Torn or worn screen media | Screen wires and panels (vibrating screen spare parts) |
| Excess undersize | Blinded screen, insufficient screen area | Screen media selection |
| High flakiness | Worn mantle–concave, wrong setting, half-fed crusher | Mantle and concave (cone crusher spare parts) |
| Non-cubical fine aggregate | Worn VSI rotor tips and anvils | VSI parts (VSI crusher spare parts) |
| Too many fines | Insufficient washing, worn screw | Screw parts (screw washer spare parts) |
| Product fluctuation in an impact crusher | Worn blow bars, apron setting | Blow bars (impact crusher spare parts) |
For the relationship between particle shape and wear parts in cone crushers, see our mantle and concave replacement guide; for the effect of apron setting on the product curve in impact crushers, see our impact apron guide.
Example Test Frequency Plan for Factory Production Control
| Test | Example frequency approach |
|---|---|
| Sieve analysis (grading) | Frequent for each product (e.g. weekly or according to production quantity) |
| Fines content and quality | Frequent, especially for sand products |
| Flakiness / shape index | Periodic |
| Los Angeles, Micro-Deval | Less frequent; when the source changes |
| Density and water absorption | Periodic |
| Freeze-thaw, chemical tests | Infrequent; when the source changes and as required by the standard |
Actual test frequencies should be set according to the annexes of the relevant standard and the requirements of the certification body.
Glossary
- d/D: The lower (d) and upper (D) sieve sizes in an aggregate size designation.
- Category: A class of value range for a property defined in the standard.
- FPC: Factory production control.
- PSV: Polished stone value; important for asphalt wearing courses.
- MDE: Micro-Deval coefficient.
- Methylene blue value: An indicator of the amount of harmful clay in the fines.
More Questions
Can the same product be used for both concrete and asphalt?
If the product meets the categories required by both standards and the project, it can be used; however, a separate declaration and testing may be required for each application.
Should there be an aggregate laboratory at the plant?
A plant laboratory is a great advantage for basic tests (sieve analysis, fines, moisture); other tests can be carried out in accredited laboratories.
How often do standards change?
Standards are revised periodically; producers need to follow the current versions.
Support from CSP Mühendislik
CSP Mühendislik supports the design of crushing, screening and washing plants for producing aggregate to target standards, the optimisation of existing plants and the supply of spare parts. You can browse our vibrating screen spare parts page for screen media and parts and our crusher spare parts page for crusher parts, and see our crushing and screening plant set-up guide for plant planning.
