EN 991:1995

Overview

EN 991:1995 is a European (CEN) standard that defines a method for determining the essential dimensions and for the verification of squareness of prefabricated reinforced components made of autoclaved aerated concrete (AAC / ACC) or lightweight aggregate concrete with open structure. The standard supports consistent dimensional control during manufacture, inspection and acceptance of precast reinforced elements in accordance with prEN 1520. The document is also published as national adoption (e.g., SIST EN 991:2001).

Key Topics

• Scope and material coverage: Applies specifically to prefabricated reinforced components produced from autoclaved aerated concrete (AAC/ACC) and lightweight aggregate concrete with an open pore structure.
• Dimension determination: Specifies the method(s) for measuring the essential overall and nominal dimensions of prefabricated elements to ensure conformity with design and production documentation.
• Verification of squareness: Defines how to check and verify component squareness (orthogonality) as part of dimensional quality control.
• Inspection intent: Focus on reproducible, standardized measurement procedures to support quality assurance, acceptance testing and compliance with prEN 1520 requirements.
• Classification and reference: Identified in the ICS classification 91.100.30 (Concrete and concrete products); cross-references prEN 1520 for related precast concrete requirements.

Applications

EN 991:1995 is used wherever consistent dimensional quality and geometric accuracy of precast reinforced components are critical:

• Precast manufacturers - to implement production control, define measurement routines and document compliance for AAC and lightweight open-structure concrete elements.
• Quality control and testing laboratories - to carry out repeatable dimension checks and squareness verification during factory inspections or third‑party assessments.
• Structural and precast engineers - to interpret as-built dimensions for design tolerances, installation planning and connection detailing.
• Contractors and erectors - to verify components before transport and installation to reduce on-site adjustments and ensure fit-up.
• Certification and regulatory bodies - as a reference for conformity assessment and product standards harmonization.

Related Standards

• prEN 1520 - referenced in EN 991 for broader requirements on prefabricated reinforced components.
• National adoptions such as SIST EN 991:2001 reflect the standard’s implementation in member countries.

This standard is essential for teams focused on precast concrete production quality, ensuring accurate dimensions, squareness, and reliable interchangeability of reinforced AAC and lightweight aggregate concrete components.