Post Tensioning Concrete Knowledge for the Home
Post tensioning concrete is a way to further enforce the concrete structure. Many people are aware of the need for rebar when building retaining walls, concrete foundations and driveways. However, not many know about the value of post tensioning concrete for a much stronger structure. Post tensioning is used very heavily in commercial applications and has been making its way into residential structures in the last few years.
What Is Post Tensioning?
Post tensioning concrete is done through the use of steel cable tendons that are stretched throughout the forms. These cables are encased within plastic sleeves that are run through the forms before the concrete is poured. The steel is then prestressed by tightening it and anchoring it to the outside of the form. When the concrete it poured, the post tensioning cable is already under stress.
Why Use Post Tensioning?
For the homeowner who wants to install a concrete patio, a retaining wall, or build a concrete driveway, they may not realize the full potential of post tensioning. This concrete building technique carries many advantages with it that make it very appealing for homeowners.
- Post tensioning concrete reduces cracking. Since there are no joints when post tensioning the concrete there isn't going to be any natural cracking caused by shrinking.
- When cracks do form, they are held together much tighter than with regular concrete pours.
- Concrete structures can be built on sandy areas or softer soils.
- Homeowners can use less concrete as the structure can be thinner. This can save money when it comes to retaining walls and new structures.
When Is Post Tensioning Used?
This type of technology has been used for close to 30 years. Mostly in commercial applications, post tensioning concrete is now used in a lot of home projects. While any type of concrete project can benefit from post tensioning, there are some applications that are well suited for this technique.
- Concrete slabs - This is now very common in slabs where the ground can move with the different seasons. With post tensioning it does not matter how firm the soil is.
- Outdoor Rec Areas - Some homeowners are installing areas where their children can play sports outside. These include tennis courts, basketball areas, and even rollerblade areas.
- Masonry Wall - Whenever there is a need for a concrete wall, post tensioning techniques are used to strengthen the wall. This is especially true of retaining walls and any outbuildings.
- Reinforce Current Structures - As concrete foundations begin to age, they can show some wear in cracks and crumbling. Adding a thin coat of concrete that is reinforced with post tensioning will help to strengthen the wall so it does not need to be replaced.
Post Tensioning Installation Techniques
When installing the post tensioning cables there are many similarities to installing rebar reinforcement. The only difference is going to be in the way that it is stretched. Rebar is basically set in the form without any further adjustments. The tendons for post tensioning will need to be stretched before the concrete is poured. Also, the spacing of the tendons should be at a specific distance. For a basic concrete slab, 48 inches in between each tendon will provide great strength.