SIST EN 1744-5:2007

SIST EN 1744-5:2007 is the Slovenian standard adopting EN 1744-5:2006 from CEN. It specifies a test method for determining acid soluble chloride salts in aggregates and expresses the result as chloride ion content. The method is intended for aggregates where the chloride does not come directly from contact with saline water, including recycled aggregates with hydrated cement and some desert aggregates.

What does SIST EN 1744-5:2007 specify?

SIST EN 1744-5:2007 specifies the procedure for measuring acid soluble chloride salts in aggregates. It is a laboratory test for mineral aggregates used when chloride may be bound in the particles rather than introduced by seawater or other saline immersion.

The document is organized into clauses for scope, normative references, definitions, reagents, apparatus, principle, sampling, test portion preparation, procedure, calculation and expression of results, and the test report. In practice, that structure takes the user from sample selection through titration to the final reported chloride content.

What are the key requirements of SIST EN 1744-5:2007?

The standard is a wet-chemistry method based on acid extraction, silver nitrate precipitation, and back titration with thiocyanate. The result is the total halide content except fluoride, expressed as chloride ion content.

Sampling and test portion

SIST EN 1744-5:2007 requires the laboratory sample to be taken according to EN 932-1 and to represent both moisture and solids. The test specimen is prepared as powdered material following EN 1744-1:1998, 12.3, and about 2 g is used for each determination. In practice, this means the sample has to be reduced and homogenized before analysis so the measured chloride reflects the whole aggregate batch.

Reagents and glassware

SIST EN 1744-5:2007 requires analytical-grade reagents and demineralised water or equivalent purity. It also sets density requirements for concentrated acids and ammonia, and specifies the reagents used in the Volhard method, including silver nitrate, thiocyanate, nitric acid, and ammonium iron(III) sulfate indicator solution. The apparatus has to comply with EN 932-5, and volumetric glassware must meet ISO 384, with ISO 1042 flasks used for the 1 l volumes.

Test principle and procedure

SIST EN 1744-5:2007 calls for boiling the powdered aggregate with dilute nitric acid, adding a known volume of silver nitrate, filtering, cooling, and titrating the excess silver nitrate with thiocyanate. The indicator is ammonium iron(III) sulfate, which shows the end point by a faint brown coloration that remains on shaking. This procedure is important because it converts the chloride content into a measured titration value that the laboratory can calculate consistently.

Special practical limits

SIST EN 1744-5:2007 notes that aggregates with significant carbonate content may froth when acid is added, so the acid should be added slowly while stirring. If the chloride content exceeds 0.85 %, the test has to be repeated with a smaller test portion. In practice, these points tell the operator how to avoid loss of sample and when the initial mass is too large for accurate titration.

Calculation and reporting

SIST EN 1744-5:2007 gives a calculation for chloride content using the test portion mass, the thiocyanate concentration, and the titration volume. The final result is the mean of two determinations and is reported to the nearest 0.01 %. That makes the method suitable for routine quality control, where repeatability and clear reporting matter.

What terms does SIST EN 1744-5:2007 define?

• Test portion - the sample used as a whole in a single test.
• Test specimen - the sample used in one determination when a method requires more than one determination.
• Laboratory sample - the reduced sample taken from a bulk sample for laboratory testing.
• Volhard method - the silver nitrate and thiocyanate titration procedure used here to measure the chloride-related result.
• Chloride ion content - the reported result from this method, expressed from the acid soluble chloride salts measured by the test.

Who uses SIST EN 1744-5:2007?

SIST EN 1744-5:2007 is used by aggregate testing laboratories, construction materials producers, and quality control staff who need to measure chloride in aggregates. It is also relevant to buyers and specifiers checking whether an aggregate is suitable for use where chloride content matters. The method is especially useful for recycled aggregate and quarry aggregate assessment in the mineral materials and construction sector.

Which standards are used with SIST EN 1744-5:2007?

SIST EN 1744-5:2007 cites EN 1744-1:1998 for preparing the test specimen, EN 932-1 for sampling, and EN 932-5 for general apparatus requirements and calibration. It also uses ISO 384 for volumetric glassware design and ISO 1042:1983 for one-mark volumetric flasks. The foreword places this part within the EN 1744 series, alongside parts covering chemical analysis, alkali reaction, eluates, water susceptibility of fillers, and recycled aggregate extract effects on cement setting time.

What does the SIST EN 1744-5:2007 document contain?

SIST EN 1744-5:2007 contains the full laboratory method, not just a brief specification. It includes a reagents section with preparation details, an apparatus list, the test principle, sampling instructions, preparation of the test portion, the procedural steps, and the calculation formula for chloride content. It also provides the required test report items and a bibliography with related aggregate and cement testing standards.