EN 1097-1-2011 pdf download.Tests for mechanical and physical properties of aggregates – Part 1: Determination of the resistance to wear (micro-Deval).
This EN 1097-1 describes the reference method used for type testing and in case of dispute for determining the resistance to wear of coarse aggregates (main text) and aggregates for railway ballast (Annex
A). For other purposes, in particular factory production control, other methods may be used provided that an appropnate working relationship with the reference method has been established. The sample is normally tested in a wet condition, but the test may also be carried out in a dry condition. This European Standard applies to natural, manufactured or recycled aggregates used in building or civil engineering.
2 Normative references
The following referenced documents are indispensable for the apphcation of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 932.2, Tests for general properties of aggregates — Part 2: Methods for reducing iaboratoiy samples EN 932-5, Tests for general properties of aggregates — Pail 5: Common equipment and calibration EN 933-1:1997, Tests for geometrical properties of aggregates — Part 1: Determination of particle size distribution — Sieving method
EN ISO 4788. Laboratory glassware — Graduated measuring cylinders (ISO 4788:2005)
ISO 3290-1, Rolling bearings — Balls — Part 1: Steel bails
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply:
test portion
sample used as a whole in a single test
3.2
test specimen
sample used in a single determination when a test method requires more than one determination of a property
3.3
laboratory sample
reduced sample derived from a bulk sample for laboratory testing
3.4
constant mass
mass determined by successive weightings performed at least 1 h apart and not differing by more than 0.1%
NOTE In many cases. constant mass can be achieved after a test portion has been dried for a pre-detecmined period in a specified oven at (110 ± 5) C. Test laboratories can determine the time required to achieve constant mass for specific types and sizes of sampie dependent upon the drying capacity of the oven used.
4 Principle
The test determines the micro-Deval coefficient WhiCh jS the percentage of the original sample reduced to a size smaller than 1,6 mm during rolling.
The test consists of measuring the wear produced by friction between the aggregates and an abrasive charge in a rotating drum under defined conditions.
When rolling is complete, the percentage retained on a 1,6 mm sieve is used to calculate the micro-Deval
coefficient.
The test method described In this European Standard is the reference method and is carried out with dry aggregate with the addition of water to give a value of MDE. Annex B gives details of how the test can be performed without the addition of water, to give a value of 1DS-
NOTE A k)wer value of the micro-Deval coefficient indicates a better resistance to wear.
5 Apparatus
Unless otherwise stated, all apparatus shall conform to the general requirements of EN 932-5.
5.1 General apparatus
5.1.1 Balance, capable of weighing both the test specimen and the charge to an accuracy of 0,1 % of the
mass of the test portion.
5.1.2 Test sieves: 1,6 mm, 8 mm, 10mm, 11,2 mm (or 12,5 mm) arid 14 mm.
5.1.3 Ventilated oven, controlled to maintain a temperature of (110 ± 5) C.
5.1.4 Means of washing the sieved sample.
5.1.5 Equipment for reducing the laboratory samples to a test portion, as described in EN 932-2,
5.1.6 Graduated glass measuring cylinder (or cylinders), conforming to EN ISO 4788, or other means
of measuring (2,5 ± 005)1 of wate”r.
5.2 Additional apparatus required for the determination of the micro-Deval coefficient of aggregate
5.2.1 A typical micro-Deval apparatus as shown in Figure 1. A micro-Deval apparatus shall have the following essential characteristics as specified in 5.2.2, 5.2.3, 5.2A, 5.2.5 and 5.2.6.
5.2.2 It shall consist of one of four hollow drums, closed at one end, having an inside diameter of (200 ± 1) mm and an Internal length measured from the base to the inside of the lid of (154 ± 1) mm. The drums shall be made of stainless steel at least 3 mm thick which are placed on two shafts which rotate on a horizontal axis.
5.2.3 The insides of drums shall be free of protrusions resulting from welding or the method of attachment. The drums shall be closed by fiat lids at least 8 mm thick and fitted with watertight and dust tight seals.
5.2.4 The abrasive charge shall consist of steel balls complying with ISO 3290-1 (10 ± 0,5) mm in diameter. NOTE The diameter of the balls can be checked quickly by passing them over parallel bars 9,5 mm apart.EN 1097-1-2011 pdf download.