🏗️ Methylene blue value of aggregates (MB) — dye adsorption by clay minerals in the 0/2 mm fraction of fine and all-in aggregates: portions of a 10 g/l methylene blue solution added to a suspension of at least 200 g of the fraction in 500 ml of water, after each portion a stain test on filter paper, result in grams of dye per kilogram of the fraction; reference method for type testing and disputes, MBF for the 0/0,125 mm fraction in Annex A, PN-EN 933-9

Construction PN-EN 933-9

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN 933-9:2022-07 (English version; the field on the card breaks off at Annex D; our translation of the Polish card text): “This document specifies the reference method used for type testing and in case of dispute for determining the methylene blue value (MB) of the 0/2 mm fraction in fine aggregates or all-in aggregates. Annex A also specifies the reference method for determining the methylene blue value (MBF) of the 0/0,125 mm fraction. For other purposes, in particular factory production control, other methods may be used provided that correlations with the appropriate reference method have been established. Annex B specifies the preparation of the 10 g/l methylene blue solution and Annex C specifies the procedure for determining the methylene blue value of kaolinite (MBk). Annexes B and C are normative. The informative Annex D…”. We read the text of the standard in the sample extract of SIST EN 933-9:2022 (EN 933-9:2022) from the cover to subclause 8.1 (preparation of the suspension, page 9); we do not have the rest — the stain test (8.2), Figure 1 (procedure diagram), calculations (Clause 9), test report (Clause 10) and Annexes A–E.

ACCORDING TO THE TEXT OF EN 933-9:2022 (foreword, Clauses 1–8.1). The standard was prepared by CEN/TC 154 “Aggregates” (secretariat BSI); it replaced EN 933-9:2009+A1:2013. Technical changes according to the foreword: addition of a reference to EN 933-2 (sieves); definition of the laboratory sample; division of the apparatus clause into 6.1 (general) and 6.2 (specific — coloured glass bottle from former Annex C); the 0,125 mm sieve moved to Annex A; the note on other stirrers moved into the main text; pre-drying temperature raised to (110 ± 5) °C for natural and manufactured aggregates and Clause 7 divided into a general part, preparation without drying and with drying; clarification of the procedure with a figure (Clause 8); alignment of scope, definitions and test report; reordering of annexes (normative first); recommendations on checking MBK moved to new C.1; restructuring of Annexes A, C and D, shortening of titles, removal of line numbers in Annex E. Scope (Clause 1): as on the card; conformity with a limit value by a single addition of the amount of dye corresponding to that value (for production control) is described in informative Annex D, an example data sheet in Annex E; warning: use of the standard can involve hazards (dust, noise, heavy lifting). Normative references: EN 932-2 (reducing laboratory samples), EN 932-5 (common equipment and calibration), EN 933-2 (test sieves). Definitions (Clause 3): laboratory sample, sub-sample, test portion, fines — fraction passing the 0,063 mm sieve, fraction di/Di, constant mass — successive weighings at least 1 h apart differing by no more than 0,1 % (usually after drying at (110 ± 5) °C). Principle (Clause 4): successive portions of methylene blue solution are added to the test portion suspended in water; after each portion the adsorption of dye by potential clay minerals is checked by a stain test on filter paper — the presence of free dye indicates the end of adsorption; the MB or MBF value is then calculated in grams of dye adsorbed per kilogram of the fraction tested. Reagents (Clause 5): methylene blue solution of standard or technical quality (10,0 ± 0,1) g/l (Annex B), used no later than 28 days after preparation, stored in the dark; distilled or demineralized water; kaolinite of known MBK value (Annex C) — a kaolinite with MBK from 1 g to 2 g per 100 g of kaolinite is recommended so as not to use excess dye. Apparatus (Clause 6, generally according to EN 932-5): burette, pipette, micropipette or bottle-top dispenser dosing 5 ml and 2 ml with an accuracy of 0,2 ml; quantitative ashless filter paper (< 0,010 % ash), 95 g/m², thickness 0,20 mm, filtration speed 75 s, pore size 8 µm; glass rod 300 mm × 8 mm; paddle stirrer with variable speed up to (600 ± 60) r/min with three or four blades (75 ± 10) mm (other stirrers if they give the same results); balance accurate to 0,1 % of the test portion mass; timer; 0,125 mm and 2 mm sieves according to EN 933-2 with a guard sieve; sieve brush; beaker of about 1 l or 2 l; 1 l glass flask; ventilated oven (110 ± 5) °C; thermometer accurate to 1 °C; spatula; desiccator; for preparing the solution — a coloured glass bottle. Test portion (Clause 7): at least 200 g of the 0/2 mm fraction, with or without pre-drying; masses to 1 g. Without drying (7.2): from the laboratory sample according to EN 932-2 two sub-samples of at least 200 g of the 0/2 mm fraction each, sieved through the 2 mm sieve (with a guard sieve, e.g. 4 mm, and a brush), the particles retained on the 2 mm sieve are discarded; on one the moisture content W = 100 × (M − M′)/M′ is determined (drying to constant mass; other methods are permitted, e.g. microwave) and it is discarded; the other is reduced to a mass greater than [200 × (1 + W/100)] g (without an exactly specified value), weighed as M0 and the dry mass M1 = M0/(1 + W/100) is calculated — the test portion for MB is then not heated. With drying (7.3): reduction according to EN 932-2, drying to constant mass at (110 ± 5) °C for natural and manufactured aggregates or below 45 °C for others, sieving through the 2 mm sieve, mass M1. Suspension (8.1): (500 ± 5) ml of distilled or demineralized water in the beaker, addition of the test portion while stirring with a spatula; the dye solution is stirred, the burette filled and the stock placed in a dark place; this is where the extract we read ends.

STATUS (cards as of 02.10.2026). The card of PN-EN 933-9:2022-07 (English version) has no “Withdrawn” header — the standard is CURRENT: published 14-07-2022, 21 pages, price group L, Construction and Building Structures Sector, KT 108 Aggregates and Building Stone, ICS 91.100.15, “Introduces: EN 933-9:2022 [IDT]”, “Replaces: PN-EN 933-9+A1:2013-07 – English version”. PN-EN 933-9+A1:2013-07 — withdrawn 14-07-2022; PN-EN 933-9:2009 (English) — withdrawn 24-07-2013 (it had replaced PN-EN 933-9:2001, Polish version). There is no Polish version of the 2022 edition.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 02.10.2026). The number 933-9 appears in 11 records at 7 laboratories: AB 937 (3), AB 054 (2), AB 1344 (2), AB 442, AB 687, AB 1414, AB 1685 (1 each). In the current scopes on the PCA website (read 02.10.2026, issues from 18.12.2025 to 21.07.2026) the number appears at all 7: with the year “2022-07” at AB 442, AB 687, AB 1344, AB 1414 and AB 1685, without a year at AB 054 and AB 937. At AB 054 part of the scope is suspended at the request of the body (from 25.06.2026 to 22.12.2026), but the rows with the number 933-9 are not set in bold italics. The “Laboratories” tab searches entries BEGINNING WITH “PN-EN 933-9” and shows all 7 laboratories and 11 positions — checked with the tab query on the labcoda.pl production server on 02.10.2026.

WHAT THE LABORATORIES TEST (positions in PCA). Aggregates — “fines content, methylene blue method” (at AB 1414 with the range (0–2) mm), usually next to the sand equivalent (PN-EN 933-8), flow coefficient (PN-EN 933-6), particle density and water absorption (PN-EN 1097-6) and impurities (PN-EN 1744-1); at AB 054 also in the group of tests of cement and raw materials, at AB 1344 next to tests of lime and fillers (bitumen number PN-EN 13179-2).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. In the solution: dye older than 28 days or stored in light gives an understated or overstated MB with a correct procedure; the concentration (10,0 ± 0,1) g/l is prepared according to Annex B. In the test portion: without drying the moisture content has to be determined on the second sub-sample and the mass converted to dry — otherwise MB is calculated on the wet mass; for pre-drying of aggregates other than natural and manufactured the temperature is below 45 °C, and (110 ± 5) °C only for natural and manufactured aggregates (raised in the 2022 edition). In the fraction: MB applies to the 0/2 mm fraction, MBF to 0/0,125 mm (Annex A); the results are not interchangeable. In the purpose: this is the REFERENCE method for type testing and disputes; production control methods require an established correlation with it, and a conformity check with a single dye dose (Annex D) does not give an MB value. In kaolinite: MBK is checked according to Annex C — a kaolinite of 1–2 g/100 g is recommended.

WHAT WE DO NOT GIVE. We do not have subclause 8.2 (stain test: portion volumes, stirring times, halo criterion), Figure 1, the formulas of Clause 9, the test report or Annexes A–E — we therefore give neither the titration procedure, the end criterion nor the formula for MB.

Method principle

Successive portions of a 10 g/l methylene blue solution are added to a suspension of at least 200 g of the dry 0/2 mm fraction in 500 ml of water; after each portion a drop of the suspension is placed on filter paper (stain test) — the appearance of free dye means that the clay minerals have adsorbed the dye to saturation; from the amount of dye used the MB value in grams per kilogram of the fraction is calculated (for the 0/0,125 mm fraction — MBF).

Applications

• Fine and all-in aggregates — assessment of harmful fines (clay minerals) in the 0/2 mm fraction; type testing and disputes (7 laboratories)
• 0/0,125 mm fraction — MBF value (Annex A)
• Production control — other methods only with an established correlation with the reference method; conformity check with a single dye dose (Annex D)

Key parameters

Standard

Standard number

PN-EN 933-9:2022-07 (wersja angielska; EN 933-9:2022 IDT)

Title (PL)

Badania geometrycznych właściwości kruszyw — Część 9: Ocena zawartości drobnych cząstek — Badanie błękitem metylenowym

Title (EN)

Tests for geometrical properties of aggregates — Part 9: Assessment of fines — Methylene blue test

Step-by-step procedure

1. Test portion

   Reduction according to EN 932-2, sieving through the 2 mm sieve, ≥ 200 g of the 0/2 mm fraction; without drying — moisture content on the second sub-sample and dry mass M1; with drying — (110 ± 5) °C or < 45 °C. PN-EN 933-9:2022-07 current (cards as of 02.10.2026).

2. Suspension

   (500 ± 5) ml of water in the beaker, addition of the test portion while stirring with a spatula; filling the burette with dye solution, stock in the dark.

3. Adding dye and stain test

   Successive portions of solution and after each a drop on filter paper until free dye is detected — portion volumes, times and criterion (8.2) NOT GIVEN.

4. Calculation

   MB in grams of dye per kilogram of the 0/2 mm fraction (Clause 9 — formula NOT GIVEN); MBF for the 0/0,125 mm fraction according to Annex A.

5. Test report

   Mandatory and optional data according to Clause 10 — NOT GIVEN; example data sheet in Annex E.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The standard warns of hazards: dust, noise, lifting of heavy loads; methylene blue stains skin and clothing — gloves; oven at 110 °C
• TECHNICAL NOTE: this is the reference method for the 0/2 mm fraction (MB); MBF (0/0,125 mm) is a different result, and a conformity check with a single dose (Annex D) does not give an MB value

Frequently asked questions