Overview
ISO 679:2009 - Cement - Test methods - Determination of strength defines the standardized procedure for measuring the compressive (and optionally flexural) strength of cement mortar. The method uses prismatic test specimens cast from a mortar mix of 1 part cement : 3 parts ISO standard sand : 0.5 parts water (w/w) and is intended for common cements and any other cement types that refer to this method. Results are reported in megapascals (MPa).
Key topics and technical requirements
- Mortar mix and specimens
- Mix ratio: 1:3:0.5 (cement : ISO standard sand : water).
- Test prism size: 40 × 40 × 160 mm.
- Specimens stored in the mould in a moist atmosphere for 24 h, then demoulded and cured under water until test age.
- Flexural testing is optional; halves are then tested in compression.
- Laboratory and curing conditions
- Standard lab temperature: (20 ± 2) °C (alternatives of 25 °C or 27 °C allowed if stated).
- Moist-air room for mould storage: (20.0 ± 1.0) °C, relative humidity ≥ 90 %.
- Water curing temperature: (20.0 ± 1.0) °C (alternatives permitted if reported).
- Apparatus and dimensional tolerances
- Mixer: stainless steel planetary mixer with specified blade/bowl design and speeds:
- Low: rotation 140 ± 5 min⁻¹, planetary 62 ± 5 min⁻¹.
- High: rotation 285 ± 10 min⁻¹, planetary 125 ± 10 min⁻¹.
- Moulds: steel, three-compartment, with strict internal tolerances:
- Length 160 ± 1 mm; width 40.0 ± 0.2 mm; depth 40.1 ± 0.1 mm.
- Flatness ≤ 0.03 mm; perpendicularity ≤ 0.2 mm; surface texture not rougher than N8.
- Internal faces case-hardened to at least HV 200 (HV 400 recommended).
- Compaction: reference jolting apparatus (details and validated alternatives described in Clause 11 and Annex A).
- Validation and quality control
- Procedures for validation testing of ISO standard sands and of alternative compaction equipment are specified to ensure equivalent strength results.
- Precision and reproducibility guidance included; laboratories are encouraged to follow ISO/IEC 17025 practices.
Applications and typical users
- Quality control and acceptance testing by cement manufacturers, independent testing laboratories, and materials departments.
- Product development and comparative performance evaluation for new cement formulations.
- Specifiers and regulatory bodies using a harmonized method for contractual compliance and performance verification.
- Note: ISO 679:2009 may not be suitable for cements with very short initial setting times.
Related standards
Keywords: ISO 679:2009, cement strength test, compressive strength, flexural strength, cement mortar, ISO standard sand, mortar testing procedure, test specimens, jolting apparatus, laboratory curing, mortar mix ratio.