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.
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.