Post-Tensioned Slab on Grade vs. Conventional Slab Reinforcement
by Tendon, on Aug 17, 2021 8:15:00 AM
Almost any construction project that involves large slabs of concrete is going to require some concrete reinforcement. That’s a fact. But the way you go about reinforcing the concrete may not be as clear-cut.
That’s because there is more than one way to reinforce concrete. The two most common methods of concrete reinforcement are conventional slab reinforcement and post-tensioned slab on grade reinforcement. Which method is best for your project will depend on a number of factors, which we explore in depth below.
Post-Tensioned Slab on Grade
At Tendon Systems, we specialize in post-tensioned slab on grade reinforcement. That’s because we believe post-tensioned slab on grade offers undeniable advantages over traditional concrete slab reinforcement.
How Post-Tensioning Works
Post-tensioning isn’t something you can see in a slab on grade foundation with the naked eye. Instead, this term implies a process that was completed before the foundation had to bear its intended service loads.
Post-tensioning tendons are steel cables that are placed inside the foundation’s mold form before the concrete is poured. The post-tensioning of the cables happens after the foundation’s concrete is poured but before load stress is applied to the slab on grade foundation. Inside their plastic sleeves within the newly poured concrete, the cables are pulled tight and anchored to the slab on either side.
This is called “post” tensioning because it happens after the concrete is poured, but it happens before the foundation has to bear any real weight.
Pros of Post-Tensioning
Post-tensioned slab on grade offers several key advantages. Chief among them is this type of slab’s ability to withstand more pressure without cracking. This advantage comes from the fact that the interior cables are already placed under stress. That means the concrete is held tightly together, and the cables are contributing their reinforcing properties at all times.
The following are some other pros of post-tensioned slab on grade:
- Fewer joints. Post-tensioning prevents cracking from shrinkage, meaning it requires fewer joints. This reduces costs.
- Thinner slabs. By adding tensile reinforcement to the slab, post-tensioning allows the slab to be thinner. This is both a design benefit and a cost-reduction perk, as thinner slabs require less concrete.
- Foundation flexibility. More strength means a greater ability to lay foundations on soft ground.
- Footing sizes are typically shallower in a PT system
Cons of Post-Tensioning
Post-tensioning is considered the gold standard of concrete slab reinforcement, but there are some potential drawbacks in certain situations:
- Complex work. Post-tensioning work is complicated, so it requires highly skilled professionals to do it right.
- Possible corrosion. This issue is most often prevented by using high-quality materials, but in some cases, the tendons inside the slab can corrode through exposure to certain materials, such as salt. Higher-quality materials will resist corrosion.
Conventional Slab Reinforcement
Like post-tensioning, conventional slab reinforcement isn’t obvious when you look at a completed slab. It’s all about what’s done — or not done — to the slab in the construction process.
How Conventional Slab Reinforcement Works
The conventional slab reinforcement process is similar to the post-tensioning process. Steel cables called tendons are placed inside a concrete slab foundation to add tensile strength. But there is a key distinction between conventionally reinforced slabs and post-tensioned slab on grade: in conventional reinforcement, the cables are not stressed before the slab has to bear its load.
Ultimately, this means that the interior steel tendons will not resist a load until the concrete slab has been compressed or cracked to the point that the service load places stress on the tendons.
Pros of Conventional Slab Reinforcement
In truth, conventional slab reinforcement offers few advantages over post-tensioned slab on grade. However, there are a couple of pros of conventional slab reinforcement that could apply in some situations:
- The construction work is relatively simple. Compared to post-tensioning, conventional concrete reinforcement is relatively simple, so less experienced and knowledgeable crews can handle it.
- It’s better than no reinforcement. If the choice is between conventional reinforcement or none at all, some reinforcement is better than none, especially when it comes to foundations.
Cons of Conventional Slab Reinforcement
Conventional slab reinforcement simply doesn’t hold its own in the post-tensioned slab on grade vs. conventional slab reinforcement fight. Here are a few of the key disadvantages:
- More steel required. This concrete reinforcement method requires more steel tendons to even come close to the strength of a post-tensioned slab.
- It’s less strong. Even with more steel, a conventionally reinforced concrete slab is going to be more likely to crack and break than a post-tensioned slab.
- It’s more expensive. The fact that conventional reinforcement requires more concrete and more steel means that this method is much more expensive than post-tensioning.
- Footing sizes are typically deeper in a conventional system
Top-Notch Slab Reinforcement with Tendon Systems
There’s more than one way to reinforce concrete, but there is only one concrete construction services partner that does it best. At Tendon Systems, we work hard every day to provide the highest quality post-tensioned slab on grade reinforced concrete available anywhere.
We believe we accomplish that mission — just ask any one of our countless happy customers how their concrete is holding up. To discuss your concrete reinforcement needs with certified professionals, reach out to Tendon Systems today. Give us a call at (678) 835-1100 or contact us online.