Why Should Buildings Use Post-Tensioning Systems?

Commercial concrete management, including post-tensioning systems, is critical to any residential or commercial high-rise and multi-level parking garage construction project. Post-tensioning involves placing prestressed steel &#;tendons&#; tightened once the concrete hardens. The additional stress of tightening compresses the concrete into its strongest state, ensuring it can support the external service loads (weight) once using the structure. 

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Failing to factor in the load-bearing capability of a structure can lead to catastrophic events, such as the collapse of the Hotel New World in Singapore in . The six-story building collapsed in 60 seconds, resulting in 33 deaths. More recently, investigators are still trying to determine the cause of a partial parking garage collapse in Baltimore in July .

This article looks closer at post-tensioning systems, explaining what they are, how they work, and their benefits to construction and architecture. We&#;ll also present some practical applications of post-tensioning concrete, criteria to consider when evaluating such systems, and where to turn for post-tensioning repairs.

What is Post-Tensioning?

Post-tensioning is a unique design technique that reinforces concrete in commercial building construction. This process helps strengthen concrete, allowing it to hold up better post-construction, keeping structures secure and stable. Post-tensioning tendons generally consist of stainless steel and reinforced cable bundles. These run inside plastic coatings or sleeves, placed inside the casings where concrete is poured before filling. Afterward, the cables are tensioned and anchored against the other concrete edges. 

The post-tension acts much the same as support beams and improves the safety and stability of concrete pillars, foundations, columns, and other structures. Post-tensioning concrete is critical in the commercial building process, and proper execution gains maximum benefits.

How Does Post-Tensioning Work?

Post-tensioning works within commercial building structures as a form of prestressing. Steel is stressed and put under tension before the concrete has hardened to support the service loads and stress of the building. Most precast, prestressed concrete has this process done as well. Post-tensioned concrete means that the concrete gets poured, and then tension is applied&#;but there is stress before applying the loads, leaving it prestressed. It is a way of preparing the structure to support the loads and stress of large commercial systems adequately. 

Reasons concrete is popular in commercial buildings and commonly seen in post-tensioning construction include:

• High durability and resiliency over long periods.

• Relatively low maintenance and upkeeps are required.

• Affordable and easy

  maintenance and repairs

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• Affordable for mass projects and large-scale production.

• The versatility of applications allows greater design creativity. 

• Easy to source locally for more affordable rates.

• It can be used in all climates and temperature extremes.

• Highly resistant to rust and corrosion.

• It is fire resistant and doesn&#;t burn easily.

• Fewer issues with pests, mold, and other issues.

With so much in favor of concrete construction, the ability to improve the features of stability, durability, and longevity with post-tensioning only adds to the appeal of concrete usage in commercial structures.

Why Post Tensioning & What are the Benefits?

Concrete is the most popular construction material in the world, and for a good reason. It&#;s widespread in commercial buildings, not only for basements and foundations but also for exterior walls. And, of course, it&#;s used frequently for sidewalks, ramps, and parking garages. The concrete used in commercial buildings is often subject to more significant pressures and stressors than concrete for residential use. When used in massive commercial building projects, this requires additional support and design considerations.

Concrete may be among the most common construction materials, but it can still come with a high price tag. Industry estimates show that a concrete parking garage could range between $4 and $7 per square foot. This price typically includes the cost of materials and labor. A smaller structure may run $5,000 to $14,000, whereas a larger building could be as much as $174,000-$490,000. Larger commercial structures, whether office buildings or parking garages, require more structural performance, which may change how you need to utilize concrete. This is where post-tensioning makes its impact. 

Considering all these features and benefits, one critical aspect of commercial concrete management and upkeep regarding degradation makes all the difference post-tensioning. 

Post-tensioned concrete has a variety of benefits, including:

• Allowing concrete to be used in higher and longer spans to create larger spaces

• Providing increased strength and support for load-bearing areas of construction

• Compensates for poor site conditions and improves structural stability

• Installs and hardens faster than other conventionally reinforced concrete structures

• It uses much less concrete, saving money and resources

• Provides flexibility and options for primary formwork and final aesthetic touches

• Increases the overall safety and durability of the structure

• Provides a faster and more practical manufacturing option

• Safe to use in nearly every building situation

• Reliable structure strength with post-tensioning

• Easily scalable for use in small, medium, and large commercial buildings

Finding the balance between affordable concrete usage and durable post-tension elements remains crucial in planning and maintaining commercial structures.

What Exactly is a Post-Tensioning System?

The post-tensioning concrete method was first developed in the early s by industry specialists such as VSL in Switzerland. Post-tensioning is often a solution for addressing design and engineering issues. It enables the operational definition of the internal load path in concrete structures by superposing a favorable state for the internal stresses. This stress reduction minimizes deformations, reduces the thickness of concrete segments, reduces reinforcement congestion, joins components without relying on wet joints, and allows high-strength steel to reinforce structural components further. 

The post-tensioning system is a structural support mechanism essential to many commercial concrete structures built today. Experts who specialize in concrete repair and upkeep utilize this system for three main reasons:

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• Structure Strength with Post-tensioning

Post-tensioning lightens the structure&#;s weight, reduces load-bearing packages, and helps improve the overall aesthetic appearance.

• Wide Application and Usage Area

It can be used in a wide variety of structures and often occurs in a wide range of systems that vary in size and usage.

• Professional Touch and Service

Post-tensioned construction offers the most suitable solution for combining production and application to create a final uniform structure.

Common Applications for Post-Tensioning 

This act of prestressing has several advantages over standard rebars:

• Significantly removes the risk of shrinkage cracks, so fewer joints are required. Shrinkage cracks occur naturally in poured concrete during the curing process as the concrete loses its moisture.

• Cracks that do occur are held tightly together and do not grow and spread.

• It allows structural concrete pieces to be thinner and lighter than they would normally.

• Engineers and designers can build slabs over expansive areas or on softer soils.

• Post-tensioning supports longer spans in elevated areas like floors, beans, and ceilings.

Criteria of a Post-Tensioning System to Evaluate

Building designers looking for a post-tensioning system should first consider three factors to avoid  costly damages and repairs down the road.

Type of structural element &#; the depth of the structural component plays a key role:

• Use of slab tendons with flat designs for thin structural elements such as floor flaps and ceilings.

• Multi-strand tendons can be used for any other application and are common in thicker heavy construction areas.

Structural design &#; taking into account specific structural design requirements:

• Post-tensioning can be introduced and might utilize internal or external tendons or, in some cases, a combination.

• Concrete slab post-tensioning tendons are bonded or unbonded based on the location, application, and desired results.

Protection against corrosion &#; Protection needed to safeguard cables against corrosion: 

• The tendon encapsulation depends on the required protection level (PL) &#; PL1, PL2, PL3, typically subject to location and environmental exposures.

• Corrosion protection is the application of anti-corrosion chemicals to prevent damage to equipment or facilities caused by corrosive processes.

Get Quality Building Repair and Management Services From Industry Experts Familiar With Post-Tensioning Systems

Finding the balance between affordable yet durable materials is vital in planning and maintaining commercial structures. Post-tensioning concrete systems allow the utilization of the durable and versatile nature of concrete, while the addition of steel cables and tension support add required structural stability. 

The post-tensioning system is the structural support working behind the scenes to provide long-lasting strength, durability, safety, and protection. Professional building management services are integral in maintaining post-tensioning systems to guard against building collapses. 

Make sure your team is ready to deal with the maintenance and upkeep of post-tensions systems. Contact The Valcourt Group today and work with industry experts who can keep your building in good working order.

It&#;s no secret why builders use post-tensioning systems in their construction; these systems are critical to strengthening concrete used in modern large-scale building projects. The same argument applies to post-tension slabs&#;a method used when pouring the slab foundation in commercial or residential construction. This article further explores post-tension slabs and some of the advantages and challenges of their usage in construction projects. 

What are Post-Tension Slabs?

The concrete industry started experimenting with strategies and techniques to strengthen and reinforce concrete in the s. The prestressing concept, now a standard in residential and commercial building construction, involves using a steel cable or tendon to squeeze and compress concrete before the concrete endures a structural load. As the construction industry continued refining its techniques to standardize prestressing, most builders eventually began using post-tensioning techniques for reinforced concrete slab foundations. The Federal Housing Administration officially endorsed the use of post-tensioned slabs in , and the building method is now embraced and co-opted as the preferred method for builders.

Post-tensioned slabs contain a tendon, or steel cable, that runs crisscrossed throughout the center of the slab after the concrete has already hardened. As the poured concrete dries, the post-tensioned cables stretch and tighten, which applies a significant force to the concrete slab. This technique strengthens and compresses the concrete, which helps reduce cracking and structural instability caused by unstable soil conditions in marshes, swamps, and lake areas. The process helps residential homes and commercial buildings achieve greater load-bearing strength. Post-tension slabs are more durable and stable than traditional slabs that lack the reinforcement of steel cables.

Why Use Post-Tension Slabs?

Concrete slabs have inherent structural weaknesses; they are especially susceptible to expansion and contraction due to seasonal fluctuations and changing temperatures. Anyone that has experienced winter knows that thawing temperatures usually lead to potholes, broken water mains, and cracks in the pavement. Concrete slabs are no exception. The swelling and contraction of soils based on their contact with water is another element that adversely affects the integrity of concrete slabs. Poor and unstable soils found in Southwestern states and Mexico lead to issues with soil expansion, making it difficult for builders to lay concrete slabs.

Builders depend on post-tension slabs to reduce the risks of cracking, contraction, and soil expansion and strengthen the foundation&#;s structural integrity.

Post-Tension Slabs: Potential Challenges

Post-tension slabs are stronger than traditional concrete slabs; however, that does not necessarily mean a post-tension slab is without challenges. Read on to learn more about builders&#; challenges when using post-tensioned slabs.

Long-Term Planning 

Post-tensioned slabs are an excellent foundation for a new structure, but builders must plan accordingly for proper drainage. Gutters, downspouts, roof pitches, and balconies redirect rainfall. Builders need to be aware of the location of drainage as it can seep into the foundation and lead to cracks.

Good Things Aren&#;t Cheap & Cheap Things Aren&#;t Good

Laying the foundation of a post-tension slab requires professional workers, quality materials, and expert knowledge to understand the job&#;s complexity. In the building and construction industry, it&#;s essential to research the service provider and contractors you partner with before signing a contract.

Check the Blueprints, Again

Since post-tension slabs require the addition of steel tendons to strengthen and reinforce the concrete, the tendons must precisely align as shown on the blueprints. Improper tendon locations can cause uplifting, as the tendon applies more force than the weight of the concrete. As a result, the concrete might be physically lifting the slab.

The Advantages of Post-Tension Slabs

Aside from producing crack-free tennis courts, smooth parking garages, and a secure foundation for someone&#;s new home, post-tension slabs offer builders an array of advantages compared to traditional concrete slabs. Here are a few of the major benefits.

Cost Savings

Post-tensioned slabs require less concrete than traditional ones, saving builders money. Post-tensioned slabs are an investment that helps homeowners reduce the risks of concrete contraction and cracks, which inevitably costs money to repair. That&#;s why post-tensioned slabs are an initial investment worth it in the long run.

Shed Some Weight

A lighter yet stronger slab of concrete allows builders to design their structure with less material and overall surface space, providing more space to build supporting pillars, walls, columns, and beams. Post-tensioned slabs are also thinner, giving builders more creative freedom when designing floors.

Minimize Risks

No matter how much planning goes into a construction project, things happen, and the idea for builders is to minimize risks. Post-tensioned slabs may help prevent cracks from forming, but concrete is not immune to the elements. The good news is that if cracks form on post-tensioned slabs, they are held together and do not spread as quickly as those on traditional foundation slabs. Therefore, post-tensioned slabs are a more durable solution.

Look to the Experts when it comes to Building Repair Services

Commercial and residential structures require rational planning and maintenance. Whether your building has a traditional concrete slab or a reinforced post-tensioned slab, building owners need to maintain the structure&#;s integrity. That&#;s why across the United States, owners and property managers rely on Valcourt as their trusted partner to protect their investments. Whether it&#;s waterproofing, restoration, or other commercial building services, Valcourt offers over 35 years of experience protecting properties from the elements. Contact Valcourt Building Services today!

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