Improve, preserve, secure

Post-Tensioning Systems: Aging, Inspection & Repair

Post-tensioning systems built throughout the 20th century were designed under concrete construction standards that differ from new construction requirements applied today, particularly in material specifications, concrete reinforcing practices, and corrosion protection requirements.

Inspections determine whether prestressing forces remain effective and whether tendons within concrete structures retain sufficient structural integrity to sustain long-term load performance.

Proven engineering solutions are now available to upgrade or modernize external post-tension tendons, even in structures that have been in service for decades. These methods restore original strength and safety levels, extending the service life of the structure and reducing the risk of unplanned failure.

Post-tensioning teams

Common Issues in Post-Tensioning Systems

The long-term performance of commercial structures with post-tensioned slabs, including parking garages, building, post-tension foundations, and bridge decks, depends on the condition of the post-tensioning system.

For commercial construction owners and infrastructure managers, the condition of external prestressing cables is a primary concern, particularly in segmental bridge decks built from prefabricated elements joined by external tendons.

Routine inspections consistently reveal the same recurring deficiencies: grout voids in ducts and anchorage caps, moisture infiltration, and chloride contamination. Left unaddressed, this damage accelerates tendon corrosion, from surface rust to full strand failure

Voids form most often at high points in the tendon profile, where incomplete grouting leaves tendons exposed to air and moisture, reducing prestress force and accelerating corrosion.

Bleed water trapped during grout curing accumulates inside ducts and, without proper sealing or drainage, initiates tendon corrosion that progressively compromises the durability of the system.

Poor joint detailing, inadequate waterproofing, or unsealed anchorage caps allow chlorides to penetrate the system. In coastal environments or structures exposed to de-icing salts, chloride ingress becomes the primary driver of accelerated corrosion in steel cables and surrounding strand assemblies.

Corrosion progresses from surface rust to section loss and wire fracture. In aging post-tensioning systems built with less corrosion-resistant steel, stress corrosion cracking in the surrounding concrete presents an additional and often unpredictable failure risk.

Our Post-Tension Maintenance Approach

Post-tensioned structures including post-tensioned slabs, parking structures, bridge decks in commercial construction require specialized maintenance and concrete reinforcement to extend tendon service life and targeted cable repair when a break occurs or remaining load-bearing capacity is in doubt.

Each project begins with a detailed inspection of existing conditions, followed by structural monitoring through instrumentation. When failure risk is identified, safety measures protect crews throughout internal repair operations. 

All work is scheduled to meet project deadlines while minimizing disruption to ongoing operations maintaining structural safety and long-term system performance.

Why Choose Freyssinet for for Maintenance of Post-Tensioning Tendons

01. Expert Analysis of Structural Defects

Our experience and expertise in repairing damaged post-tensioning systems drives professional assessments that evaluate current conditions and identify deterioration before it affects structural performance. We help owners understand how their cables are behaving and what intervention, if any, is needed.

02. Customized Monitoring Programs

We work with you to develop inspection and testing programs tailored to your structure’s specific configuration, providing a reliable framework for the long-term maintenance of post-tensioning systems and early detection of deterioration before it becomes critical.

03. Targeted Structural Studies

Every structure has unique characteristics. We conduct specialized laboratory and field testing to accurately diagnose the extent and severity of any deterioration or damage, so that repair strategies are grounded in verified field data.

04. Proven Strengthening Solutions

Our teams are experienced in working with aging or corroded external prestressing cables. We clean and treat affected areas, and when needed, replace outdated systems with modern, safer technologies through efficient repair solutions that restore load capacity and extend service life.

Our Post-Tensioning System Repair Process

Evaluation of Cable Conditions

In addition to standard inspections, we offer advanced diagnostic techniques to assess concrete repair needs and identify force loss in tendons before structural repair becomes necessary. These methods help detect grout voids, corrosion, and load deficiencies identifying exactly what repairs are needed across the system.
  • Visual inspection of anchor heads
    with ultrasonic testing to
    assess corrosion
  • Sonic and electromagnetic testing of
    accessible duct sections
  • Cross-bow testing to measure residual
    force in wires and strands

Tendon Acoustic Monitoring

For cables considered at risk, where corrosion of wires or strands could lead to full cable failure, we offer acoustic monitoring solutions. These systems help detect wire breaks in real time, track their progression, and support informed decisions about service levels and post-tensioning repair and maintenance needs. This approach is a core component of any proactive structural monitoring program.
  • Detection of wire failure
    using acoustic sensors
  • Real time alerts delivered by email
  • Support in interpreting wire
    failure progression

Maintenance Team Safety

When corrosion is suspected in external prestressing cables located in confined spaces, targeted safety measures are required to protect inspection and maintenance crews. We support clients in assessing risks and selecting protective strategies suited to the specific conditions of each site.
  • Assessment of traffic restrictions or
    alternating traffic to maintain
    safety levels
  • Design and installation of safety straps
    to contain energy release during
    cable failure
  • Implementation of protective systems
    for safe repair operations
    in confined spaces

Cable Protection Corrosion Retrofitting

In many older structures including post-tension slabs and bridge decks, prestressing cables were not properly injected or were installed using outdated materials and techniques.Loose sheaths and poor-quality grout can leave tendons in concrete members vulnerable to corrosion. Freyssinet offers targeted preservation solutions to restore protection and extend the service life of these systems.
  • Vacuum re-injection of voids in tendons
  • Reinstate the watertightness of ducts
    and anchor caps
  • Removal of poor-quality cement grout
    where feasible

Detensioning of External Prestressing Cables

When corrosion in external prestressing tendons of a post-tensioned concrete structure is too advanced, detensioning may be required to safely remove and replace the affected cables. Freyssinet offers several proven detensioning techniques,used based on the specific needs of each structure, the condition of the cable, the structure, and the potential risks associated with energy release. These services are a key component of safe and effective maintenance post-tensioning maintenance operations.
  • Cable detension by cutting
  • Controlled detension of tendons
  • Tendon detension using
    elasto-plastic dampers

Evaluation of Cable Conditions

In addition to standard inspections, we offer advanced diagnostic techniques to assess concrete repair needs and identify force loss in tendons before structural repair becomes necessary. These methods help detect grout voids, corrosion, and load deficiencies identifying exactly what repairs are needed across the system.
  • Visual inspection of anchor heads
    with ultrasonic testing to
    assess corrosion
  • Sonic and electromagnetic testing of
    accessible duct sections
  • Cross-bow testing to measure residual
    force in wires and strands

Tendon Acoustic Monitoring

For cables considered at risk, where corrosion of wires or strands could lead to full cable failure, we offer acoustic monitoring solutions. These systems help detect wire breaks in real time, track their progression, and support informed decisions about service levels and post-tensioning repair and maintenance needs. This approach is a core component of any proactive structural monitoring program.
  • Detection of wire failure
    using acoustic sensors
  • Real time alerts delivered by email
  • Support in interpreting wire
    failure progression

Maintenance Team Safety

When corrosion is suspected in external prestressing cables located in confined spaces, targeted safety measures are required to protect inspection and maintenance crews. We support clients in assessing risks and selecting protective strategies suited to the specific conditions of each site.
  • Assessment of traffic restrictions or
    alternating traffic to maintain
    safety levels
  • Design and installation of safety straps
    to contain energy release during
    cable failure
  • Implementation of protective systems
    for safe repair operations
    in confined spaces

Cable Protection Corrosion Retrofitting

In many older structures including post-tension slabs and bridge decks, prestressing cables were not properly injected or were installed using outdated materials and techniques.Loose sheaths and poor-quality grout can leave tendons in concrete members vulnerable to corrosion. Freyssinet offers targeted preservation solutions to restore protection and extend the service life of these systems.
  • Vacuum re-injection of voids in tendons
  • Reinstate the watertightness of ducts
    and anchor caps
  • Removal of poor-quality cement grout
    where feasible

Detensioning of External Prestressing Cables

When corrosion in external prestressing tendons of a post-tensioned concrete structure is too advanced, detensioning may be required to safely remove and replace the affected cables. Freyssinet offers several proven detensioning techniques,used based on the specific needs of each structure, the condition of the cable, the structure, and the potential risks associated with energy release. These services are a key component of safe and effective maintenance post-tensioning maintenance operations.
  • Cable detension by cutting
  • Controlled detension of tendons
  • Tendon detension using
    elasto-plastic dampers

Discover Our Projects

Repairs
Maryland, United States

Montgomery College Parking Garage

When a post-tensioned floor unexpectedly sagged in a multi-level parking garage at Montgomery College in Takoma Park, our team acted quickly to complete the necessary structural repairs while keeping disruptions to garage users at a minimum.
Discover more
Repairs
Charleston, North Carolina

Cumberland Street Parking Deck

Freyssinet partnered with Charleston County to inspect and repair post-tensioned tendons at the Cumberland Street Parking Deck. The project was completed swiftly and safely, preserving access to a vital downtown parking facility.
Discover more
Repairs
South Carolina, United States

Charleston Place Hotel

Freyssinet was trusted to perform complex structural repairs at the Charleston Place Hotel, restoring post-tensioned concrete systems in a live luxury setting. The project showcased our expertise in precision engineering and discreet execution within high-profile environments.
Discover more

Contact Freyssinet Today!

Thank you for your interest in Freyssinet, Inc. To discuss a specific project, sign up for our newsletter, schedule a presentation, or request other information, please fill out the form below and we will contact you shortly.

  • This field is for validation purposes and should be left unchanged.
  • *Mandatory fields