Post-Tensioned Versus Conventionally Reinforced Slab Foundations

Post-tensioned slabs-on-ground have shallower stiffening beams than conventionally reinforced slabs-on-ground.

This fact alone makes the post-tensioned slab potentially more flexible than a conventionally reinforced slab.  There are other aspects, however, that, in practice, mitigate this difference.

Post-tensioned slabs are less likely to develop cracks due to bending.

Since the concrete in a post-tensioned slab is placed in compression, cracks due to bending are less likely than in conventionally reinforced
slabs.

Since the cables cannot be tensioned for at least 7-days after the concrete is placed, visible RTS cracks are almost inevitable in a post-tensioned slab.  These cracks will tighten when the cables are tensioned. However, certain conditions, including debris lodging in the crack, may prevent an RTS crack from fully closing.  These cracks are not significant structurally to the performance of the foundation whether they close or remain open.

Post-tensioned slabs are more likely to develop cracks due to restraint-to-shrinkage.

Post-tensioned slabs-on-ground can be less expensive.

If several foundations are to be constructed using the same design, a post-tension design will almost always be less costly to the builder.  This situation common with large builders; constructing post-tensioned slabs can bring significant cost savings for such builders.

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