We’ve been talking a lot about post-tensioning lately because in Denver, we have an interesting combination of many old parking garages around the city, combined with a lot of new engineers. Post-tensioning has been an effective technique for reinforcing concrete in parking structures and garages for decades, and even though they have good track records with regard to maintenance, it’s important to identify and correct problems early.

When an inspection reveals a problem that needs to be addressed, it’s critical to choose a company with post-tension expertise to execute the repair. Certification from the Post Tensioning Institute (PTI) alone is often not a sufficient indicator for safe, quality repairs. Experience is key.

PTI is a nonprofit organization that has generated manuals, best practice procedures, and certification classes designed to train engineers and field personnel in correct post-tensioning installation. However, installation and repair are totally different animals. The PTI training manuals, while important, cannot be applied to both activities.

Plus, no two repairs are exactly alike. Sometimes technicians don’t even know what they’re dealing with until they start removing concrete from a structure — a potentially dangerous process for anyone without adequate hands-on experience.

That’s why direct experience with post-tension repairs is crucial. This includes experience with building inspections, practical knowledge of specialized tools, and recent history performing repairs on a variety of different structures.

HEXA technicians have comprehensive training including hands-on experience with installation, assembly, and safety regarding post-tensioning replacement and repair so they can:

  • Help diagnose cracking slab or joint misalignment
  • Figure out why chemicals are leaking from within the walls
  • Determine the weak points in a structure and calculate exactly how to strengthen them
  • Keep safety the utmost priority

Post-tension repair is an important investment and trusting your job to just anyone can be a very costly mistake. Reach out to us today, and let’s chat about how we can help support your post-tension repair needs.

Post-tensioning has been an effective technique for reinforcing concrete in parking structures and garages for decades. Here’s some background on the basics of post-tensioning. Although post-tensioned structures typically have better track records when it comes to maintenance, they are complex systems that are subject to some specific vulnerabilities, especially when initial installation was less than ideal. Identifying and correcting problems requires special investigation and repair expertise and techniques.

There are several challenges to consider with post-tension repair work:

  • Many buildings have unknown history. Present-day building owners may not know what materials or systems were involved when their structures were built. Trained experts can spot and diagnose issues quickly.
  • Specialized knowledge is rare. Knowing how to repair older concrete structures requires specific experience and specialty tools. Dealing with post-tensioning systems can present conundrums for any contemporary engineer who is unfamiliar with how to diagnose or repair its unique issues.
  • Repairs can be costly when contractors aren’t properly trained. When a structure or building needs a repair, specifically post-tension repair, the investment can get out of control if the contractors don’t possess practical application and hands-on experience. These repairs also come with inherent challenges and safety risks.

This doesn’t mean post-tension repair needs to be a huge stressor. Still, it’s critical to choose a team with extensive knowledge as well as field experience with safe, efficient diagnostics and restoration techniques. Post-tension repair is one of HEXA’s specialties and a technique in which we have certification through the Post-Tensioning Institute.

Contact us and we’ll perform a complimentary inspection with an estimate for repair work.

Check out our Post-Tension Repair brochure here.

Pioneered in the 1930s by French, structural engineer, Eugene Freyssinet, post-tensioning is a system for reinforcing concrete, structural elements. It consists of pre-installed steel tendons that run the length of the beam or deck span, are anchored at both ends, and then are stressed when installed.

By applying a pre-stress load, post-tensioning pre-emptively counteracts tensile stresses and is therefore an active reinforcing system, whereas rebar is passive. By keeping the concrete in compression, post-tensioning strengthens the concrete and foundation and helps reduce cracking. While the buildings can stand on their own, the post-tensioning carries the load.

Post-tensioning is typically used in parking decks, garages, bridges, and nuclear reactors built since the 1970s and 1980s. With age comes wear and deterioration. What original designers didn’t foresee, however, was the extensive use of salts and de-icing chemicals on these structures in cold weather. This contributed to faster wear and a greater degree of damage, including rust, which must be identified and repaired to keep the structures safe.

Many engineers evaluating the condition of these older structures were not even born when these structures were built. New engineers must assess buildings and make determinations when there is quite possibly no engineering information available from the original design. In addition, today’s engineers may not be as familiar with older systems which can be very different from the modern systems they install today. For example, parking decks built today are waterproofed; 50 years ago, they were paper wrapped. Most owners don’t know what materials were used in their structures, and most engineers don’t know how to deal with button head or rod systems from the early 1970s.

That’s where Colorado’s experts in post-tension repair come in. HEXA’s team has the in-depth know-how to repair and restore these structures safely and efficiently. We can help you understand what cracking, joint/slab misalignment, or chemical leaks from walls means for the future of your structure – and what it takes to repair it. Reach out today, and let’s chat about how we can help you add many useful and safe years to the life to your structures. Check out our Post-Tension Repair brochure here.

Post-Tensioning is one of HEXA’s specialties and a technique in which we have certification through the Post-Tensioning Institute. Our recent Post-tension Repair blog explained our post-tensioning work at a Denver Metropoint parking garage. Because of our expertise in Colorado post-tension repair, we’ve received inquiries and interest in the techniques involved, so we’d like to share some additional information about this versatile method of reinforcing concrete.

A Unique Structural System

Post-tensioning is often an excellent choice for Colorado’s weather and is used in many types of structures. It is an especially effective technique for reinforcing concrete in parking structures and garages. According to the Post-Tensioning Institute, “Post-tensioned concrete provides a structurally efficient, reliable, and cost-efficient solution” for concrete parking garages.

Cast-in-place, post-tensioned concrete has become the system of choice for parking operators, commercial building owners, universities, hospitals, and public institutions for a number of reasons:

  • Post-tensioned structural systems often provide initial cost savings and better life-cycle costs, compared to other framing systems.
  • Since they are more water-tight and resistant to cracking, they typically have fewer maintenance issues.
  • Wide beam spacing and the flat surfaces provided by post-tensioning enhance lighting which improves security, provide a more welcoming environment, and a superior riding surface.
  • The slab thickness and beam widths in post-tensioned structures result in long spans which allow for versatility and adaptability to other structural components such as slopes to drains, ramps, irregular plan layouts, and cost-effective architectural treatments.
  • Post-tensioning provides outstanding structural integrity, including under abnormal and catastrophic loading. This means reduced vibration and resistance to wind, which can be important in our Colorado climate.
  • Post-tensioned concrete is not poured as deep as in other techniques so there is less drying time required, which can also be important during some seasons in Colorado. This technique can also reduce structural depths, excavation, and soil retention costs.

Considerations

Although post-tensioned structures typically have better track records when it comes to maintenance, they are complex systems that are subject to some specific vulnerabilities, especially when initial installation was less than ideal. Identifying and correcting problems requires special investigation and repair expertise and techniques.

Problems that can occur include corrosion and cracking of sheathed, steel cables. In grouted structures, improper installation of grout can leave voids and residual moisture which can lead to damage and deterioration. Post-tensioned steel is also more susceptible to damage from chloride-induced pitting corrosion, hydrogen embrittlement, and stress corrosion cracking. Tendon damage can occur and, although there may be external signs of distress, specific inspection methods may be required to find or confirm damage. For example, we use special techniques to evaluate corrosion inside sheathed cables.

Trust the Experts

HEXA’s crews are certified in post-tension repair. We are equipped to get the repairs done right, including taking steps to prevent problems from occurring again.  When you can’t afford to gamble with the integrity of and investment in your concrete, contact us. We’ll perform a complementary inspection and our post-tension experts will take the stress out of your repair work. Check out our Post-Tension Repair brochure here.