ISO 1920-6:2019

Overview

ISO 1920-6:2019 - Testing of concrete - Part 6: Sampling, preparing and testing of concrete cores - specifies a standardized method for taking cores from hardened concrete, examining and preparing those cores, and determining their compressive strength. The standard covers core drilling, specimen dimensions, end preparation and compression testing requirements, but does not prescribe where to drill or how to interpret core results. It recommends that all parties agree on the need for coring and interpretation before testing.

Key topics and technical requirements

• Scope and limits
  • Method for sampling, preparation and compressive testing of concrete cores.
  • Does not advise on drilling locations or result interpretation.
• Apparatus
  • Core drill with diamond-impregnated bit; drilling rig must be rigidly anchored.
  • Compression testing machine with load accuracy ±1.0% and annual calibration.
  • Platens hardness ≥ 550 HV; auxiliary platen thickness ≥ 23 mm; surface roughness Ra 0.4–3.2 µm.
  • Balance accurate to 0.1% of specimen mass; callipers to ±0.01 mm.
• Taking cores
  • Avoid joints, edges and reinforcement where possible; prefer compression zones.
  • Typical core diameters: 100 mm, 125 mm or 150 mm (±10 mm); diameter should be >3× maximum aggregate size (100 mm preferred for max aggregate ≤19 mm).
  • Length and diameter selection depend on comparison basis (cube or cylinder strength).
• Length-to-diameter (l/d) ratios
  • For comparison to cylinder strength: 2.0 (±5%).
  • For comparison to cube strength: 1.0 (±5%).
  • Conversion methods are permitted when l/d < 2.0.
• Examination & measurements
  • Visual inspection for defects; measure diameter and length to ±0.1 mm and record mass/density when required.
• Preparation tolerances
  • End flatness ±0.05 mm; perpendicularity ±0.5 mm; preferred end preparation by grinding.
• Storage & testing
  • Compression testing procedures and storage provisions are defined to ensure reproducible core strength results.

Applications and users

ISO 1920-6 is used for:

• Quality control and site acceptance testing by contractors and concrete suppliers.
• Materials testing laboratories performing core strength determination.
• Structural engineers, forensic investigators and consultants assessing in-situ concrete strength.
• Asset owners and project teams requiring standardized core sampling and compressive strength data.

Keywords: ISO 1920-6, testing of concrete, concrete cores, core drilling, compressive strength, core preparation, compression testing machine.

Related standards

• ISO 1920-4 - Testing of concrete - Part 4: Strength of hardened concrete (end preparation and compression testing methods referenced).
• ISO 1920-5 - Testing of concrete - Part 5: Density and water penetration depth (density/saturation procedures).

For accurate implementation, users should consult the full ISO 1920-6:2019 document and coordinate procedures and result interpretation with all stakeholders before coring.