🛤️ Soluble binder content of an asphalt mixture

Construction PN-EN 12697-1

Overview

THE KEY NOTATION (measurement of 23.09.2026). The key "PN-EN 12697-1" matches on the beginning of the notation and shows 39 laboratories / 60 entries. Sixteen of these entries, at eight laboratories, are OTHER PARTS of the standard (-11, -12, -17, -18) — but only ONE laboratory is on the list solely because of another part; the other seven also have records of part 1. A colon after the number ("PN-EN 12697-1:") would cut off the other parts together with that one laboratory, but it would also take away TWO laboratories whose record is correct, only without the year ("PN-EN 12697-1") — the list would shrink to 36 laboratories / 41 entries. That would trade one laboratory that does not belong on the list for two that do, so the key stays without a colon — for the same reason as with PN-EN 1338.

The standard PN-EN 12697-1 describes methods of determining the soluble binder content in samples of asphalt mixtures; they are suitable for quality control during the production of the mixture in the plant and for checking conformity with the product specification. The standard takes a harmonised approach which allows certain differences in the details of the procedures of individual laboratories: clause 5 describes the basic operations, Annex A gives guidance (the scheme A.1), and Annex B equivalent variants of the apparatus: hot extractors (with a paper or a mesh filter), the Soxhlet extractor, the bottle shaker, the centrifugal extractor, cold dissolution by stirring and the automatic extractor; for the separation of the filler a continuous-flow centrifuge, a pressure filter or bucket centrifuges. Annex C gives the determination of the mineral residue in the extract by ignition, and Annex D guidance for polymer-modified binders.

The soluble binder is the percentage by mass of the binder which can be extracted from a water-free sample; the insoluble binder is the percentage by mass of the binder remaining on the aggregate particles after the extraction. The 2020 edition replaced PN-EN 12697-1:2012: the title no longer restricts the method to hot mixtures, the accuracy of the balance was changed to ± 0.1 g, clause 4 was supplemented with the preparation of samples of mixtures with a high content of mineral constituents, a procedure for the automatic extractor was added and a clause on the precision of automatic devices.

In the Polish requirements WT-2 2014 (GDDKiA) the soluble binder content S is the reference value for assessing the bitumen content of a mixture: it is determined as the mean result of at least 8 extractions during the validation of production, and the insoluble binder Bn = B − S (B — the total bitumen) must not exceed the theoretical value Bn = 0.014·F + 0.1 (F — the filler content in %). The standard warns that the solvents (dichloromethane, trichloroethylene, toluene, xylene, perchloroethylene and others) are harmful to health and are subject to occupational exposure limits.

Method principle

The determination of the binder content in a test portion of the mixture prepared according to PN-EN 12697-28 comprises four operations: (a) extraction of the binder by dissolution in a hot or a cold solvent, (b) separation of the mineral constituents from the binder solution, (c) determination of the amount of binder by difference of masses or by recovery of the binder from the solution (B.3), (d) calculation of the soluble binder content S as a percentage of the mass of the original dry test portion (the formulae 5.5.2–5.5.5 for the difference method, for full recovery and for recovery from part of the solution with a volumetric or a gravimetric calculation). The extraction procedure must ensure that no soluble binder remains on the particles, and the separation of the filler that the residue after the ignition of the recovered binder does not exceed 0.5 % (filler < 6 % of the mass of the aggregate) or 1 % (filler ≥ 6 %) according to Annex C.

Applications

• Quality control of asphalt mixtures in the plant (validation of production, factory production control)
• Checking the conformity of a mixture with the specification and with the type test (WT-2 2014: the soluble binder S as the reference value)
• Recovery of binder from a mixture for further tests (penetration, softening point)
• Determination of the grading of the aggregate recovered after extraction according to PN-EN 12697-2
• Testing of mixtures with polymer-modified binders (Annex D)

Key parameters

Standard

Standard number

PN-EN 12697-1:2020-08

Title (PL)

Mieszanki mineralno-asfaltowe — Metody badań — Część 1: Zawartość lepiszcza rozpuszczalnego

Title (EN)

Bituminous mixtures — Test methods — Part 1: Soluble binder content

Step-by-step procedure

1. Preparation of the test portion

   Prepare the laboratory samples according to PN-EN 12697-28 so as to obtain test portions; with mixtures of a high content of mineral constituents take the capacity of the apparatus of B.2 into account. If the sample may contain water: dry it to constant mass, determine the water content according to PN-EN 12697-14 or proceed according to PN-EN 12697-28.

2. Weighing

   Weigh the test portion to 0.1 g and place it in the extraction apparatus in accordance with the requirements of the method chosen from B.1.

3. Extraction of the binder

   Dissolve the binder in a hot or a cold solvent so that no soluble binder remains on the particles of the aggregate (in a few cases all traces are hard to remove — see A.4).

4. Separation of the mineral constituents

   Collect the binder solution and separate the filler by the method of B.2 (continuous-flow centrifuge, pressure filter, bucket centrifuge); the effectiveness is confirmed by a residue after the ignition of the recovered binder of ≤ 0.5 % or ≤ 1 % according to Annex C (the check is not made on every sample).

5. Recovery of the aggregate

   Transfer the clean aggregate onto a tray, evaporate the solvent from the aggregate and from the apparatus, transfer any remaining fine mineral particles from the apparatus onto the tray, weigh it and record the mass of the aggregate. If need be, determine the grading of the recovered aggregate according to PN-EN 12697-2, taking into account the filler retained on the filter.

6. Amount of binder

   The difference method: add the mass of the filler from the filter to the mass of the recovered aggregate. The recovery method: recover the binder from the solution according to B.3.

7. Calculation and test report

   Calculate S as a percentage of the mass of the original dry test portion according to 5.5.2 (difference), 5.5.3 (full recovery) or 5.5.4/5.5.5 (recovery from part of the solution, a volumetric or a gravimetric calculation); for dried test portions M is the mass of the dry test portion and Mw is disregarded. For binders with a significant insoluble fraction, calculate the total binder according to A.4.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Chlorinated and aromatic solvents (dichloromethane, trichloroethylene, toluene, xylene, perchloroethylene) are harmful to health and subject to occupational exposure limits — work in a fume hood, train the staff, wear gloves resistant to solvents
• Hot extractors and the evaporation of the solvent — a risk of burns and of fire; no naked flame near flammable solvents
• Keep trichloroethylene in tight containers protected from UV; check regenerated solvent for acidity

Frequently asked questions