Can you cut into post tension slab?
The only concern is to always remember not to cut or drill into post-tensioned concrete slabs, since once a tendon has been cut, it is very difficult to repair. Many post-tensioned slabs will be stamped to alert the owner and any renovation contractors that the slab is post tensioned.
Can I drill into a post tension slab?
Yes, you can drill into a PT slab. However, you want to make sure you know where the cables are located. I design PT slabs and repairs. It is rare for a tendon to break out of the slab on a residential house. It will shoot out the plugs around the slab edge. If it hit someone it could break a leg.
How to reinforce and straighten a fence post?
- To break up an old concrete footing, start by digging 6 to 8 inches around perimeter of the footing. ...
- With the post free, break the concrete up using a hand-held sledgehammer and cold chisel. ...
- Drive a stake into the ground about 24 to 36 inches from the metal fence post to brace the fence, and then screw the stake to the brace with a ...
How to install post fence on an existing slab?
Installing vinyl fence posts on an existing concrete slab How to Set a Vinyl Post on a Concrete Surfac . Use the post as a template by positioning it exactly where you want it on the concrete surface. Draw the outline of the post on the concrete. Mark the centers of 4 holes that are to be drilled into the concrete.
What happens if you cut a post tension slab?
Cutting a tensioned cable, or tendon, can endanger the contractor and compromise the structural integrity of the slab. Building professionals frequently use ground-penetrating radar (GPR) to locate cables within concrete slabs and reinforce the slab during and after cutting operations.
Can you cut pre tension slab?
The inside of the opening is now completely free of any stress and can be cut like any other slab opening. 10.
How deep are the cables in a post tension slab?
8"The plan maps show the rebar at 3" depth, and the post-tension cables at 8" depth. Discerning a post-tension cable from rebar generally requires scanning a larger area to properly understand the layout of structural elements in a slab.
Can a post tension slab be repaired?
0:583:09What's the fix for a broken post tension slab cable? - YouTubeYouTubeStart of suggested clipEnd of suggested clipWell the best fix is to call a post-tension repair company and they'll re-cable. It because there'sMoreWell the best fix is to call a post-tension repair company and they'll re-cable. It because there's a sleeve.
Is post tension 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.
How long do post tension slabs last?
about 15-20 yearsPost-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.
Can you drill screws into post tension slab?
PT slabs on ground can be placed and stamped just like with any other concrete slab. Surfaces can be stained or overlaid. The only concern is to always remember not to cut or drill into post-tensioned concrete slabs, since once a tendon has been cut, it is very difficult to repair.
What year did post tension slabs start?
The first post-tensioning in U.S. building construction was in the mid- to late 1950s in buildings using the lift- slab construction method.
How can you tell if concrete is post tensioned?
How to tell if you have a post tension slab. Most homes that have post tension slabs have a sign that is stamped into a concrete garage floor, often near the edge of the garage door right in plain sight. Older homes with post tension slabs may have a plastic or paper sign fastened to the wall.
How do you demo a post tension slab?
After the structure has been gutted, each floor slab is typically removed by skid steer loaders using hydraulic and impact hammers. The tension from the cables is released and can be cut with hydraulic shears or torches.
Are post tension slabs used in Florida?
High-rise residential concrete construction in South Florida typically consists of unbonded post-tensioned concrete slab construction.
How do you seal post tension cables?
0:511:49How do I maintain cable ends on a post-tension slab? - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd then maybe spray paint the metal in there and then use some sack Crete and bonding agent and goMoreAnd then maybe spray paint the metal in there and then use some sack Crete and bonding agent and go ahead and float over the top of it and that at least prolong it eventually it's gonna go way.
How do you demo a post tension slab?
After the structure has been gutted, each floor slab is typically removed by skid steer loaders using hydraulic and impact hammers. The tension from the cables is released and can be cut with hydraulic shears or torches.
How does post tension slab work?
Post-tension concrete slabs are used to create a monolithic (single pour) slab that is stronger than a traditional slab without reinforcement. This is achieved by laying out high-strength steel cables in a crisscrossed grid pattern throughout the foundation prior to pouring the concrete.
When did PT slabs start?
When was post-tensioned concrete first seen in this country? The first use was on the Walnut Lane Bridge in Philadelphia in 1949.
What are post tension cables?
Post tension cables are used in concrete construction to add strength to thin and long slabs. This allows more span lengths between support columns. The cables have steel wires within plastic sheath. They are tensioned after pouring concrete,hence the name post-tension cables.
What happens if you cut concrete slab?
Additionally, the concrete of the slab is in heavy compression. If you cut it or try to trench, you create a weak spot where a structural failure can occur. An architect shouldn't be advising or doing this.
How to core a Pt slab?
If it's a pt-slab on grade, you'll need to cut a hole large enough to dig, then use a directional boring rig to core through the earth to that hole. Expensive since you'll also need to excavate at the exterior for the boring rig and route the sewer around the building outside the foundation edge. If you are a zero lot line, you are down to ejector pumps and a pit to pump it up high enough to route overhead.
How far away from the centerline of a bundle should you cut your tendons?
The rule of thumb we've operated with is 6" away from the centerline of a bundle. So if your tendons are 4'-0"x4'-0" on center, you can get a 3'-0" square cut out of the middle of that, but then you cannot cut anything in any adjacent strand bays.
Is a small penetration ok?
kjdt. History · Contact. Small penetrations are usually ok - not a big deal - as long as you know where the tendons are and you stay far enough away from them. You have to have testing done - GPR usually - to get a survey of the tendons (obviously don't trust any shops or as-builts).
Can you re-set up a sandbox?
Yes, but only if the last one fails to topple and the workers re-set them all up again for another go.
Can you trench a sewer line?
Best method... xray and core through. You can not trench. Hopefully, you are above grade PT. That isn't that bad and I've done that on multiple projects. Just locate the cables, avoid, and core straight through; sewer gets run below that slab. Get a structural engineer to design it.
Do you need to cut a strand?
If you do absolutely need to cut a strand, it can be done but is time consuming and expensive. The strand first needs to be de-tensioned, meaning the ends of the strand at the edge of slab need to be accessed. Once the stresses are out, the strand can be cut, new ends added, and it can be retensioned.
Where to find post tension slab?
Look for a stamp in the concrete that identifies the post-tension slab (usually near the garage door or another easily noticeable location).
How to tell if a foundation is post tension?
You may also be able to see signs of a post-tension slab on the outside of your foundation. Look for circular concrete patches about two to four feet apart.
What is slab leak?
Slab leaks are one of the most involved plumbing repairs that we handle at Custom Plumbing. When your home is built on a post-tension slab foundation, though, things get even more complicated.
Can you tunnel under a slab?
You won’t damage any of your home’s floors. You won’t lose access to your home while repairs are being completed. By tunneling, you won’t risk introducing mold to the interior of your home.
Can you cut a post tension slab?
Some leaks under a home’s slab require cutting through the slab to access the broken pipe. You should NEVER cut through a post-tension slab. The reason is that you could damage or sever one of the cables running through the concrete. Doing so could risk the integrity of the foundation and possibly even cause one of the cables to rip through the foundation and seriously injure someone.
Can you replace a cut cable?
The cut cable can be pulled and replaced and the sleeves on the others will need to be repaired. It is not any easy or cheap process but it is reparable. You absolutely need an engineer to design the repair. They may say replace the cable or they may add some steel reinforcement in that area or both.
Can you re-fill a trench with concrete?
Don't let them re-fill the trench with concrete until you have a signed/sealed repair plan from a PE. If they repaired and you weren't aware, that sounds like they're trying to hurry and bury their mistake.
Can you repair a broken cable without retensioning?
And yes, as stated above, that repair they did on your broken cable without retension ing did absolutely nothing for you.
Why use post-tensioning in a 2 way layout?
Designers of office buildings, hospitals, and other medical facilities are often reticent to use post-tensioning because of this misconception.
How does posttensioning work?
Reality: Okay, this one is true. However, the use of post-tensioning also results in many other cost savings to the owner that are often overlooked. The following is a list of additional cost-savings to the owner: 1 Overall building height is reduced. This can be used to add more leasable space within the same building height, it can be used to increase ceiling height, or it can be a cost savings. 2 Because the building height is reduced, there is a reduction in all building services that are tied to building height such as mechanical, electrical, plumbing, elevators, etc. 3 Because the building height is reduced, there is a savings in the cost of the building façade. 4 Because the building height is reduced, operating costs such as heating and cooling costs are reduced for the life of the building. 5 When used in below-grade applications, excavation costs are reduced. 6 Formwork and reshoring costs are reduced.
What does it mean when a steel wedge cracks?
Cracks indicate that the wedges are conforming more tightly and getting a better grip on the steel strands as they hold the prestress force in place. It is common to see cracks in 2-part wedges after stressing. It is less common in 3-part wedges.
Why is there a reduction in the cost of the building façade?
Because the building height is reduced, there is a savings in the cost of the building façade.
Why is building height reduced?
Because the building height is reduced, there is a savings in the cost of the building façade. Because the building height is reduced, operating costs such as heating and cooling costs are reduced for the life of the building. When used in below-grade applications, excavation costs are reduced.
Is precast or post-tensioned parking more expensive?
Over the life cycle of the building, precast is often the more expensive approach.
Is post tensioning a good idea?
Reality : It’s important to remember that the overall budget of a structure is more than just the initial construction cost. While upfront costs for a post-tensioned parking structure can be higher than for precast, maintenance and repair costs are considerably lower. Over the life cycle of the building, precast is often the more expensive approach. If durability, minimal maintenance, an open layout, reduced vibration, and better distribution of light in the structure are of the highest priority, post-tensioning is truly the superior building choice.
How much tension does a post tension cable slab have?
Cutting cables – The cables installed are usually pulled so they each have approximately 28,500 lbs. of tension.
Why does clay expand?
These clays expand when they become moist and contract when they lose moisture. Many times the clay soils under the middle of a home are moist, but the clay soils on the perimeter of a home become dehydrated. The perimeter area contracts and the middle area remains swollen or expanded.
What causes a loud noise when cutting cables?
The released tension will find the path of least resistance. A very loud noise similar to thunder usually occurs if the cables are cut while coring or saw cutting a slab. Experienced saw cutters will know immediately something has happened. Many factors can influence what will actually occur.
Can you get injured by standing on top of a cable?
Injury can occur if someone is standing on top of the cable when it releases. The main reason to use our services is to avoid the worst case situation when a length of cable whips out of the slab and injures someone. This is a very serious situation, of course.
