SIST EN 14721:2005+A1:2008

Overview

EN 14721:2005+A1:2007 (CEN) specifies standardized test methods for measuring the fibre content of metallic fibre concrete. It defines two complementary procedures: Method A for determining fibre content in hardened concrete cores, and Method B for measuring fibre content in fresh concrete samples. The standard is intended for quality control and verification of fibre dosage in precast and cast-in-place products, but does not apply to sprayed concrete.

Key topics and requirements

• Scope
  • Two methods: Method A (hardened specimen) and Method B (fresh specimen).
  • Exclusion: sprayed concrete is not covered.
• Sampling and specimen volumes
  • Method A: at least 3 cores; each core volume ≥ 1 dm3; total specimen volume ≥ 5 dm3.
  • Method B: at least 3 samples; each sample volume ≥ 3 dm3 (1 dm3 = 1 L).
• Apparatus (examples)
  • Method A: core drill, callipers, balance for mass-in-air/water, water tank, scales for fibre mass, magnet (for ferrous fibres).
  • Method B: calibrated watertight container (≥ 3 dm3), scoop, compacting means (internal vibrator or vibrating table), sieve/filter for washing, scales and magnet.
• Procedures
  • Method A: drill cores perpendicular to surface, determine core volume (calculation or water displacement per EN 12390-7), crush core, extract and clean fibres, weigh fibres.
  • Method B: take representative increments from the discharge stream, fill and compact container, wash out cement/fines to recover fibres, clean/dry and weigh fibres.
• Expression of results
  • Fibre content Cf is calculated from extracted fibre mass and sample volume. Units: Cf in kg/m3 using fibre mass (g) and sample volume (dm3): Cf = m / V (with m in g, V in dm3).
• Test report must include
  • Identification, method used, placing/compacting info (Method B), sample volumes (±0.02 dm3), fibre masses (±0.5 g), calculated values, average, deviations from the standard, testing place/date and responsible person.
• Precision
  • Indicative: Method A may lose up to 5% of fibre mass during crushing/collection; Method B reports no fibre loss.

Applications and users

• Quality control for metallic fibre reinforced concrete in precast and in-situ production
• Verification of contractual fibre dosage and conformity testing
• Testing laboratories, precast manufacturers, structural engineers, contractors, specification writers, certification bodies, and research institutions
• Forensic investigation of concrete elements where actual fibre content is in question

Related standards

• EN 12350-6 - Testing fresh concrete: density (used for container calibration/volume)
• EN 12390-7 - Testing hardened concrete: density and water displacement (used for core volume)

Keywords: EN 14721, metallic fibre concrete, fibre content measurement, Method A, Method B, test method, fresh concrete, hardened concrete, CEN, quality control.