What happens if you cut a post tension slab?
What happens if you cut a post tension slab?
Post-tension cables are steel wires inserted into plastic sheathing laid in place while pouring the concrete slab. Once the slab cures, qualified personnel apply tension and grout the cables. Cutting a tensioned cable, or tendon, can endanger the contractor and compromise the structural integrity of the slab.
How deep are the cables in a post tension slab?
Now that being said, you still need to take precautions, but post tension slabs are usually 10″+ thick. The cable is going to be in the centre of the slab. If you are still horribly paranoid, you can always have the slab x-rayed.
How do you cut a concrete slab for a post?
Use a standard circular saw, equipped with a corundum or diamond blade, for small tasks. For slabs, it’s best to cut through the top inch, then use a sledgehammer to break off the rest. The jagged edge left below the cutting line provides a good rough edge for the new concrete to bond to.
Can a post tension slab be repaired?
Post tension (PT) tendon systems are primarily used for large slab construction projects. Since the early 1950’s, post tension tendons have been used in the design of concrete structures. For such critical structural element, the repair should only be completed using a certified, experienced repair contractor.
How long will a post tension slab last?
about 15-20 years
Conventional concrete & rebar foundations last about 20-30 years before failure begins to occur. Post-tension slabs are lasting about 15-20 years and are failing at a much higher rate. Post-tension slabs are created with concrete trenches around the perimeter of the house where the external walls will be placed.
Do post tension slabs have rebar?
Post-tension slabs are created with concrete trenches around the perimeter of the house where the external walls will be placed. The top slab of concrete is thinner than with concrete & rebar.
Can a hacksaw cut concrete?
The carbide hacksaw blades cut ceramics, steel, aluminum, plastics, concrete, brick and wood cleanly and quickly in all directions.
Does a concrete slab need to be cut?
Depth of Sawcuts “The minimum depth of sawcut using a wet conventional saw should be the greater of at least 1/4 of the slab depth or 1 in. Some slab designers require cutting the slab the following day to 1/4 of the slab depth to deepen the 1 in. (25 mm) early-entry sawcut and ensure the joint activates.”
Do post tension slabs crack?
Post-tensioned concrete slabs are typically expected to crack less than other slabs because post-tensioning produces a compressive stress that must be exceeded before enough tensile stress develops to cause cracking. For a 100,000 ft2 post-tensioned slab, this would result in an estimated 900 lineal ft of cracks.
Where is post tension slab used?
Post-tensioning now is used extensively in bridges, elevated slabs (parking structures and residential or commercial buildings), residential foundations, walls, and columns. Jim Rogers Bending and flexing creates high tensile forces that can cause the concrete floor slab to crack.
Is post tension slab better than rebar?
Post-tensioning, which is a form of prestressing, has several advantages over standard reinforcing steel (rebars): It reduces or eliminates shrinkage cracking-therefore no joints, or fewer joints, are needed. Cracks that do form are held tightly together. It allows slabs and other structural members to be thinner.
What is post tension in construction?
Post-tensioning is simply a way to reinforce in a more active way. Post tensioning is a technique for reinforcing concrete. Post-tensioning tendons, which are prestressing steel cables inside plastic ducts or sleeves, are positioned in the forms before the concrete is placed.
Errors that lead to cracks. When errors are made on-site during the post-tensioning process, the ability of the reinforcement to prevent cracking is decreased. As a result, even though post-tensioning is meant to help prevent a slab from cracking, the slab can still crack if the tensioning process is done incorrectly.
What is post tension construction?
Definition of Post tensioned concrete in Construction. A structural procedure of strengthening concrete slabs and components that involves the installation of high tensile strength cables. These cables are placed in the concrete slab prior to the actual placement of the concrete.
What is post tension Foundation?
A post-tensioned foundation is a concrete slab foundation that is reinforced with stranded steel cables that are tensioned after the concrete hardens. The stranded cables are slid inside of plastic-sheathing, which prevents the stranded steel tendons from touching the concrete.
