Overview
ISO 24684-2:2023 is an international standard that specifies a test method for determining soluble sulfate salts in aggregates used for concrete. This part of ISO 24684 focuses on determining soluble sulfate salts particularly in aggregates exposed to saline water, such as sea-dredged aggregates. The procedure involves chemical extraction and volumetric analysis to accurately assess sulfate content, which is crucial to ensure concrete durability and performance.
This standard ensures that aggregates with potentially harmful sulfate contents are properly evaluated to prevent sulfate-induced concrete degradation. It complements concrete quality control protocols by providing reliable chemical testing methods for sulfate detection.
Key Topics
-
Scope and Applicability
Focuses on soluble sulfate salts in aggregates affected by contact with saline water. Suitable for aggregates sourced from marine environments.
-
Test Principle
Extraction of sulfates using dilute hydrochloric acid followed by precipitation as barium sulfate. Quantification is conducted via gravimetric analysis after titration operations.
-
Terminology
Defines key terms such as test portion, test specimen, and laboratory sample to ensure consistent usage across test procedures.
-
Reagents and Apparatus
Utilizes analytical grade reagents like silver nitrate, barium chloride, hydrochloric acid, and ammonium hydroxide. Testing requires equipment such as balances, ovens, muffle furnace, and standard laboratory glassware.
-
Testing Procedure
Includes sample preparation (drying, crushing, grinding) to a defined particle size and mass. Sulfate extraction is done by boiling with hydrochloric acid, followed by filtration, neutralization, and precipitation. The final barium sulfate precipitate is ignited and weighed to calculate sulfate content.
-
Precision and Repeatability
Provides guidance on the expected repeatability and reproducibility of results. Requires at least two determinations per sample, with re-testing if results vary excessively.
-
Reporting Requirements
Test reports must specify the method, sample source, dry sample mass, sulfate results, any deviations from procedure, and testing date.
Applications
-
Concrete Aggregate Quality Control
Essential for verifying chemical safety of aggregates, specifically sulfate levels that can cause delayed ettringite formation and concrete deterioration.
-
Marine and Sea-Dredged Aggregate Testing
Designed for aggregates sourced from saline environments to assess contamination by soluble sulfate salts.
-
Construction Materials Laboratories
Standardized method for chemical property analysis of aggregates, aiding material certification and compliance with construction specifications.
-
Environmental and Durability Assessments
Helps predict potential sulfate-related damage in concrete structures exposed to marine or brackish water.
-
Research and Development
Useful for developing sulfate-resistant concrete mixes and aggregate processing technologies.
Related Standards
-
ISO 24684 (Series)
The overall series deals with test methods for chemical properties of aggregates used in concrete.
-
ISO 10693
Methods for detection of total sulfur compounds in aggregates and cement.
-
ISO 14296
Test methods for assessing chloride content in aggregates to mitigate corrosion risk.
-
ASTM C1580
Standard test method for sulfate soundness of aggregates, related to sulfate durability effects.
-
EN 1744-1
European standard for chemical analysis of aggregates, supporting sulfate and chloride testing protocols.
By adhering to ISO 24684-2:2023, industry professionals ensure that aggregates meet chemical safety criteria, achieving reliable and durable concrete performance. The standard’s chemical test method for soluble sulfate salts plays a critical role in managing sulfate-related risks in concrete construction.
Open preview (PDF)Aggregates for concrete — Test methods for chemical properties — Part 2: Determination of soluble sulfate salts
