ISO 24684-2:2023

INTERNATIONAL ISO
STANDARD 24684-2
First edition
2023-01
Aggregates for concrete — Test
methods for chemical properties —
Part 2:
Determination of soluble sulfate salts
Granulats pour béton — Méthodes d'essai relatives aux propriétés
chimiques —
Partie 2: Dosage des sels de sulfate solubles
Reference number
© ISO 2023
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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 1
5 Reagents . 2
5.1 General . 2
5.2 Reagents for determination of acid-soluble sulfates . 2
5.3 Apparatus . 2
6 General requirements for testing .3
6.1 Number of tests . 3
6.2 Repeatability and reproducibility . 3
6.3 Expression of mass, volume, factors and results . 3
6.4 Drying of materials . 3
6.5 Ignitions of precipitates . 3
6.6 Check for the absence of chloride ions (silver nitrate test) . 4
7 Determination of acid soluble sulfates. 4
7.1 Principle . 4
7.2 Preparation of test portion . 4
7.3 Procedure . 4
7.4 Calculation and expression of results . 5
8 Test report . 5
Annex A (informative) Determination of acid soluble sulfates . 6
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and pre-
stressed concrete, Subcommittee SC 1, Test methods for concrete.
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iv
INTERNATIONAL STANDARD ISO 24684-2:2023(E)
Aggregates for concrete — Test methods for chemical
properties —
Part 2:
Determination of soluble sulfate salts
1 Scope
This document describes the procedure for the determination of soluble sulfate salts which can be
present in aggregates. The test is suitable for aggregates where the sulfate content derives directly
from contact with, or immersion in, saline water, e.g. typical sea-dredged aggregates.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
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
4 General
An aggregate test specimen is extracted with water to remove sulfate ions. The method of analyses of
the extract is based on the Volhard titration where an excess of silver nitrate solution is added to the
sulfate solution and the unreacted portion is back titrated with a standardized solution of thiocyanate,
using ammonium iron (III) sulfate solution as an indicator.
The sulfate are expressed in terms of, and reported as, the sulfate ion content as a percentage by mass
of aggregate.
5 Reagents
5.1 General
5.1.1 Unless otherwise stated, use onl
...