FND2 is typically a C25/30 or C28/35 strength class concrete (25–35 N/mm² compressive strength at 28 days). Key requirements include:

  • Minimum cement content: Often 320–330 kg/m³ (some sources note around 300 kg/m³ with specific cements).
  • Maximum water/cement ratio: Around 0.55.
  • Sulfate-resisting cement combinations, such as Portland cement with high levels of ground granulated blastfurnace slag (e.g., CEM III/A + SR) or other approved blends that limit permeability and resist chemical attack.
  • Default consistence (workability): S3 (slump typically 80–180 mm, target around 120 mm), suitable for trench fill or pumped placement. It is a quality-assured designated mix supplied by ready-mixed concrete plants with certification.