Overview
ISO 1920-3:2019 - Testing of concrete - Part 3: Making and curing test specimens specifies the shapes, dimensions, tolerances and methods for making and curing concrete test specimens used in strength tests. The standard covers cubes, cylinders and prisms, required apparatus, preparation (sampling, filling, compaction, levelling, marking, capping), and curing procedures (including considerations for hot climates). It is intended to ensure consistent, repeatable concrete test specimens for compressive, tensile splitting and flexural tests.
Key topics and technical requirements
- Specimen types and nominal sizes
- Cubes: nominal l = 100, 120, 150, 200, 225, 250, 300 mm (preferred 100 mm and 150 mm).
- Cylinders: diameters d = 100, 113, 125, 150, 200, 250, 300 mm; height normally h = 2d (preferred 100×200, 125×250, 150×300).
- Prisms: basic size l = 100, 150, 200, 250, 300 mm with length L ≥ 3.5 l (preferred 100×400 and 150×600 mm).
- Tolerances and geometric requirements
- Dimensional tolerance on designated size: ±0.5% for cubes, cylinders and prisms.
- Cube flatness: 0.03 mm (new moulds), 0.05 mm (in use); parallelism and perpendicularity limits also defined.
- Cylinder flatness: ±0.0005·d (or ±0.02·d for unbonded capping methods); straightness and perpendicularity tolerances specified.
- Apparatus
- Moulds should be steel or cast-iron (other materials require equivalence data); watertight and non-absorbent. Lightweight cylindrical moulds specified in Annex C.
- Measurement tools (calipers, gauges, squares) capable of verifying ±0.5% dimensions and specified flatness.
- Compaction means: internal vibrator minimum 120 Hz (7 200 cpm); preferred compaction methods selected on the basis of slump.
- Specimen preparation and curing
- Sampling, filling, compaction, surface levelling, marking and capping procedures are defined.
- Curing regimes and special guidance for hot climates are included.
- Capping methods for cylinders (including unbonded capping) are covered.
Practical applications and users
ISO 1920-3 is used by:
- Construction materials laboratories for compressive strength testing and quality control.
- Contractors and engineers for routine site testing and acceptance of concrete deliveries.
- Certification bodies and research institutions requiring reproducible concrete test specimens.
- Forensic investigators assessing structural failures or disputes involving concrete strength.
Benefits include improved reproducibility of test results, consistent specimen production, and compliance with international testing practice.
Related standards
- ISO 1920-1 - Testing of concrete: Sampling of fresh concrete (normative reference)
- ISO 1101 - Geometrical product specifications: tolerancing (used for form and flatness definitions)
Keywords: ISO 1920-3, testing of concrete, making and curing test specimens, concrete specimen dimensions, cube and cylinder tolerances, concrete curing, moulds, compaction, compressive strength testing.
