ISO 5091-4:2023

Overview

ISO 5091-4:2023 is an international standard issued by ISO that addresses the structural intervention of existing concrete structures using cementitious materials with a focus on the jacketing method. This document provides thorough guidance for the design, construction, and maintenance of interventions where reinforcing materials-such as reinforcing steel or fibre-reinforced polymer (FRP) grids-are installed around existing concrete columns or beams and these members are encased (jacketed) with cementitious materials. The standard is designed to ensure structural integrity and performance in the face of mechanical, chemical, biological, and physical challenges, as well as to address existing defects in concrete structures.

The jacketing method described in ISO 5091-4:2023 is widely recognized for its effectiveness in strengthening and rehabilitating concrete elements, especially in seismic upgrades, repairs following structural damage, and extending the service life of critical infrastructure.

Key Topics

• Scope of Jacketing: Focuses on the application of additional layers of cementitious materials and reinforcement to concrete columns, beams, or piers to enhance their strength, ductility, and durability.
• Investigation of Existing Structures: Guides on document review, on-site inspections, and detailed damage assessments to categorize existing performance and establish intervention needs.
• Intervention Design Principles: Emphasizes rational planning, integration of jacketing systems with existing members, and appropriate selection of materials to fulfill required structural performance.
• Material Selection: Outlines requirements for cementitious materials, reinforcing products (steel or FRP), bonding agents (primers, adhesives, grouting), and filling materials, ensuring compatibility and durability.
• Construction and Quality Control: Covers construction planning, surface preparation, assembly of reinforcement, execution of concrete or mortar jacketing, surface protection, quality control, and inspection protocols.
• Maintenance: Stresses the need for ongoing inspection and maintenance to monitor long-term performance and address any emerging deterioration.

Applications

ISO 5091-4:2023 applies to a wide range of situations and industries, including:

• Seismic Retrofit: Strengthening bridge piers, columns, and beams in earthquake-prone regions to enhance seismic resistance.
• Structural Repair: Addressing damage from impacts, overloading, settlement, or original construction deficiencies in concrete structures.
• Durability Enhancement: Protecting structures against aggressive environmental actions such as sulfate attack, freeze-thaw cycles, thermal effects, and moisture-induced deterioration.
• Infrastructure Upgrades: Extending the life span and load-carrying capacity of aging infrastructure, such as bridges, buildings, and transportation facilities.
• Defect Mitigation: Remediating reinforcement corrosion, thermal cracking, and other forms of deterioration that threaten structural safety and serviceability.

The jacketing method is especially relevant to owners, engineers, design consultants, and contractors involved in maintenance, repair, and strengthening of concrete structures.

Related Standards

• ISO 5091-1:2023 – Structural intervention of existing concrete structures using cementitious materials – Part 1: General principles
• ISO 22966 – Execution of concrete structures
• ISO 16311 (various parts) – Guidelines for the maintenance and repair of concrete structures

These related ISO standards provide complementary principles and procedures, ensuring a comprehensive approach to concrete structure intervention and repair when implementing jacketing or alternative strengthening strategies.

By following ISO 5091-4:2023, stakeholders can ensure a high level of structural reliability when applying cementitious jacketing solutions, addressing both current challenges and future durability of concrete infrastructure. Adhering to these guidelines also facilitates compliance with international best practices for concrete repair and reinforcement, ultimately supporting safer and longer-lasting structures.