🏗️ Resistance of aggregate to wear — the micro-Deval coefficient
In short
Wear of 2 × 500 g of 10/14 mm aggregate with 5 kg of Ø 10 mm steel balls and 2. The test is performed according to PN-EN 1097-1:2011; Fraction and test portions: 10/14 mm, two test portions of (500 ± 2) g; the laboratory sample ≥ 2 kg of 10–14 mm particles. The procedure comprises 8 steps; it is used for: Type testing and factory production control of aggregates for concrete and for asphalt mixtures, Selection of aggregate for concretes exposed to wear (road pavements, floors), Classification of coarse aggregate into the categories MDE10–MDE35.
At a glance
- Standard: PN-EN 1097-1:2011
- Category: Construction
- Procedure steps: 8
- Fraction and test portions: 10/14 mm, two test portions of (500 ± 2) g; the laboratory sample ≥ 2 kg of 10–14 mm particles
- Grading of the test portion: 30–40 % passing 11.2 mm or 60–70 % passing 12.5 mm
- Abrasive charge: (5000 ± 5) g of steel balls of Ø (10 ± 0.5) mm according to ISO 3290-1 per drum
Overview
The standard PN-EN 1097-1 describes the reference method, used in type testing and in cases of dispute, for determining the resistance to wear of coarse aggregates (the main text) and of aggregates for railway ballast (Annex A). It applies to natural, manufactured and recycled aggregates for building and civil engineering. The sample is usually tested wet, with water added (the MDE coefficient); Annex B describes the dry test (MDS). The present description is based on the edition PN-EN 1097-1:2011, which the Polish Committee for Standardization has withdrawn and replaced by PN-EN 1097-1:2024-05 — the differences in the new edition are to be checked before implementation.
The micro-Deval coefficient is the percentage of the original sample reduced to a size below 1.6 mm during the tumbling; a lower value means a better resistance to wear. The test consists in measuring the wear produced by friction between the particles of the aggregate and the abrasive charge in a rotating drum under prescribed conditions. The categories of resistance to wear of coarse aggregate according to the micro-Deval coefficient: MDE10, MDE15, MDE20, MDE25, MDE35 (as well as declared and no requirement).
In concretes exposed to wear (pavements, industrial floors) an aggregate with a low micro-Deval coefficient is recommended. The test is carried out alongside the Los Angeles test: both methods use the same 10/14 mm fraction with similar grading requirements, but they differ in the apparatus, in the abrasive charge and in the presence of water.
Method principle
Two test portions of (500 ± 2) g each of 10/14 mm aggregate are placed in separate stainless steel drums of an internal diameter of (200 ± 1) mm and an internal length of (154 ± 1) mm, (5000 ± 5) g of steel balls of a diameter of (10 ± 0.5) mm and (2.5 ± 0.05) l of water are added to each, they are closed with tight covers and rotated at a speed of (100 ± 5) rpm for (12 000 ± 10) revolutions. After the test the material from each drum is washed on a 1.6 mm sieve protected by an 8 mm sieve, dried to constant mass and the residue m is weighed; the coefficient MDE = (500 − m)/5 is calculated for each test portion to 0.1.
Applications
- Type testing and factory production control of aggregates for concrete and for asphalt mixtures
- Selection of aggregate for concretes exposed to wear (road pavements, floors)
- Classification of coarse aggregate into the categories MDE10–MDE35
- Testing of aggregates for railway ballast (Annex A)
- The dry test (the MDS coefficient, Annex B) and other fractions (Annex C)
Key parameters
| Parameter | Value |
|---|---|
| Fraction and test portions | 10/14 mm, two test portions of (500 ± 2) g; the laboratory sample ≥ 2 kg of 10–14 mm particles |
| Grading of the test portion | 30–40 % passing 11.2 mm or 60–70 % passing 12.5 mm |
| Abrasive charge | (5000 ± 5) g of steel balls of Ø (10 ± 0.5) mm according to ISO 3290-1 per drum |
| Water | (2.5 ± 0.05) l per drum |
| Revolutions | (12 000 ± 10) revolutions at (100 ± 5) rpm |
| Result | MDE = (500 − m)/5 for each test portion, to 0.1 |
Standard
- Standard number
- PN-EN 1097-1:2011
- Title (PL)
- Badania mechanicznych i fizycznych właściwości kruszyw — Część 1: Oznaczanie odporności na ścieranie (mikro-Deval)
- Title (EN)
- Tests for mechanical and physical properties of aggregates — Part 1: Determination of the resistance to wear (micro-Deval)
Step-by-step procedure
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Laboratory sample
The sample delivered to the laboratory is to contain at least 2 kg of 10–14 mm particles (other fractions for other applications — Annex C; state the fraction in the test report).
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Separation of the fractions
Sieve on 10, 11.2 (or 12.5) and 14 mm sieves into the fractions 10/11.2 (or 10/12.5) and 11.2/14 (or 12.5/14) mm; wash each fraction separately in accordance with 7.1 of PN-EN 933-1:1997 and dry it at (110 ± 5) °C to constant mass.
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Making up the test portion
After cooling, mix the fractions so that 30–40 % passes 11.2 mm or 60–70 % passes 12.5 mm; reduce in accordance with PN-EN 932-2 to two test portions of (500 ± 2) g.
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Charging of the drums
Place each test portion in a separate drum, add (5000 ± 5) g of steel balls and (2.5 ± 0.05) l of water, fit the covers and place the drums on the rollers.
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Tumbling
Rotate the drums at a speed of (100 ± 5) rpm for (12 000 ± 10) revolutions.
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Recovery of the material
Collect the aggregate and the balls into a bowl without losing any particles; wash the inside of the drum and the covers with a wash bottle, keeping the washings. Tip the material with the washings onto the 1.6 mm sieve protected by the 8 mm sieve and wash it with a jet of clean water; separate out the balls.
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Drying and weighing
Dry the residue from the 1.6 and 8 mm sieves at (110 ± 5) °C to constant mass and determine the mass retained on the 1.6 mm sieve in accordance with PN-EN 933-1.
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Calculation
MDE = (500 − m)/5 for each test portion to 0.1 (m — the mass retained on the 1.6 mm sieve in grams); a lower value means a better resistance to wear.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Micro-Deval apparatus | One to four stainless steel drums (wall thickness ≥ 3 mm) of internal Ø (200 ± 1) mm × (154 ± 1) mm, with no protruding welds, with covers of ≥ 8 mm and water- and dust-tight seals, a motor of about 1 kW, a revolution counter stopping the drive | — |
| Steel balls | Ø (10 ± 0.5) mm according to ISO 3290-1 (the diameter checked by rolling them between bars 9.5 mm apart) | — |
| Test sieves | 1.6; 8; 10; 11.2 (or 12.5) and 14 mm | — |
| Balance | Accuracy 0.1 % of the mass of the test portion, for weighing the test portion and the charge | — |
| Ventilated oven | (110 ± 5) °C | — |
| Measuring cylinder | According to EN ISO 4788 for measuring out (2.5 ± 0.05) l of water; equipment for washing and for reducing samples according to PN-EN 932-2 | — |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Water | — | (2.5 ± 0.05) l per drum for the wet test; water for washing the fractions and the material after the test |
Health and safety (OHS)
- The drums with the balls and the water are heavy and noisy — hearing protection, fit and remove them with the drive switched off
- Check the tightness of the covers before starting (water and balls thrown out by centrifugal force)
- The oven at 110 °C — heat-resistant gloves when taking the bowls out
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN 1097-1:2011 — “Tests for mechanical and physical properties of aggregates — Part 1: Determination of the resistance to wear (micro-Deval)”.
How does this method work?
Two test portions of (500 ± 2) g each of 10/14 mm aggregate are placed in separate stainless steel drums of an internal diameter of (200 ± 1) mm and an internal length of (154 ± 1) mm, (5000 ± 5) g of steel balls of a diameter of (10 ± 0.5) mm and (2.
What is the measuring range and accuracy?
Fraction and test portions: 10/14 mm, two test portions of (500 ± 2) g; the laboratory sample ≥ 2 kg of 10–14 mm particles; Grading of the test portion: 30–40 % passing 11.2 mm or 60–70 % passing 12.5 mm; Abrasive charge: (5000 ± 5) g of steel balls of Ø (10 ± 0.5) mm according to ISO 3290-1 per drum; Water: (2.5 ± 0.05) l per drum.
How long does the test take?
The procedure comprises 8 steps. The standard does not give a duration for every stage — the laboratory's own procedure decides.
What equipment is required?
Micro-Deval apparatus, Steel balls, Test sieves, Balance, Ventilated oven, Measuring cylinder.
Where is this test used?
Type testing and factory production control of aggregates for concrete and for asphalt mixtures; Selection of aggregate for concretes exposed to wear (road pavements, floors); Classification of coarse aggregate into the categories MDE10–MDE35; Testing of aggregates for railway ballast (Annex A); The dry test (the MDS coefficient, Annex B) and other fractions (Annex C).
What safety precautions apply?
The drums with the balls and the water are heavy and noisy — hearing protection, fit and remove them with the drive switched off; Check the tightness of the covers before starting (water and balls thrown out by centrifugal force); The oven at 110 °C — heat-resistant gloves when taking the bowls out.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN 1097-1.