Nov 12, 2009 the post tensioning will typically keep it closed up tight each of those tendons has about 30,000 lbs of tension on them. Some of the cracks are more than 30 feet long, and i can feel a slight difference in the rise on each side you can even. B9472, is staffed with an experienced team of skilled professionals who undertake all aspects of structural concrete rehabilitation, restoration, repair and reinforcement for a variety of commercial and industrial buildings, parking structures and slabs. Foundation repair cost how much is foundation repair. Post tensioning technology has changed from paper wrap systems, button head tendons to push through systems and others. Sep 21, 2014 posttensioned slab procedure duration. Read more about post tension slabs and why you should not cut or core one if a garage has a post tension slab there is usually either a sign stamped in the concrete floor saying it is a post tension slab or a plastic sign on the garage wall stating its a post tension slab. Post tension repair and modification restruction corporation. Posttension basics how posttensioned slabs are built. Neglecting to design general anchorage zones or delegating this responsibility. You need a structural engineer familiar with post tension design and construction. Repair for leaking waterstops published in our june 1984 issue, page 594.
Posttensioned slab repair posttensioned slab repair kmead structural op. This video shows how i repaired a crack in a concrete slab in our patio. Concrete repair expert james belville will take the time to fully explain the nature of your homes foundation. Post tension installation and repair vector construction provides commercial building concrete services to clients throughout canada, including toronto, vancouver, calgary, edmonton, ottawa, winnipeg, saskatoon, ontario, bc, manitoba and alberta, as well as the u. Slab foundation repair cost can be expensive and may even cause collateral damage with extra costs as well. A normal slab is basically a rcc reinforce cement concrete slab where as a post tentioned slab is the psc prestressed concret slab. Post tension slab preparations the foundation in question was a posttension cable reinforced foundation as opposed to a foundation which is reinforced with steel rebar see the typical photograph in this article. Two broad categories of cracking can occur in groundsupported posttensioned slabs. In this article, ill be giving homeowners some necessary information about the characteristics, advantages, disadvantages, and common questionsconcerns that i receive regarding posttensioned foundations. Tunneling versus busting through slab for plumbing repairs. Post tensioned slabs are a great tool to help reduce joints and control cracks. Post tensioned foundation information for the homeowner. Post tensioning repair robinson parking garage structural. What is the difference between normal slab and post.
Cracks may indicate serious structural problems and others may be insignificant. In this article, ill be giving homeowners some necessary information about the characteristics, advantages, disadvantages, and common questionsconcerns that i. Post tension pt tendon systems are primarily used for large slab construction projects. Structural engineers recommend cumberland post tension because of their long standing knowledge and solid reputation in the industry. The aci 302 provision setting a reasonable level of cracking first appeared in the 1996 revision of aci 302. Flexural cracking in the slabs of older beamandslab parking structures is often observed running parallel to the beams in the positive moment area near the slab midspan. Contact us regarding troubles with your post tension slab. Slab foundation repair cost what you can expect to pay. As a result, even though posttensioning is meant to help prevent a slab from cracking, the slab can still crack if the tensioning process is done incorrectly. Nov 02, 2010 slab foundation repair cost can be expensive and may even cause collateral damage with extra costs as well.
The cracks in this case ranged in width measured across the crack from hairline less than 116 to. Avoiding post tension errors which result in cracking. This list is compiled from field notes and observations. There is no hard and fast rule for when foundation repairs are needed, individual opinions can vary widely always get an opinion from an engineer rather than a foundation company that has an interest in selling you repairs. Posttension foundation repair expert phoenix arizona. Posttensioned concrete corrosion mitigation posttension. Cracks, cracks, cracks what is a reasonable level of cracking. The lobby level of the garage has a 4inch topping on a 10inch posttensioned slab with posttensioned beams spaced at 27 feet.
Our future vision pti envisions a future in which post tensioning is the first choice for reinforcing all structures. Marks were made on the slab and the locations were measured and charted on. Foundation repairs made easy magnolia home inspection. We recommend using pt for temperature and shrinkage reinforcement. Issues in posttensioned construction concrete construction. If this edge movement is prevented, either the slab or the restraining element will most likely crack.
Posttension basics how posttensioned slabs are built the. I had a call this morning from a prospective client who was concerned about cracks in the concrete foundation of the home they. I used some quikrete crack sealant from home depot to fill the cracks. Until the cables are stretchedelongated, they cannot provide any crack control, which. The use of post tension tendons allows the engineer to design for larger slab construction spans typically used in parking structures or high rise condominium construction. During preconstruction a sonar scan was performed which indicated the locations and depth of the post tension cables. We have worked closely with engineers, designers, and even other contractors to help establish effective and wellstabilized building structures.
Jul 28, 2007 a post tension slab will usually have a stamp located by the garage entry either just inside the garage door our just outside the garage door. The slab was constructed with post tensioned cable. The robinson center parking garage, located in downtown little rock, was showing signs of deterioration within the slabs and beams. Concrete posttension slab checklist 2007 marshall hansen rev. A psc is applied with a compressive stress on the cross section in advance before the application of loading on. Concrete is exceptionally strong in compression, but weak in tension. Jan 20, 2016 rebar reinforcement in this case is technically allowed by code but in our experience, a properly designed post tensioned concrete slab will minimize cracking due to shrinkage. There are several post tension slab problems which can be avoided. Post tension repair building restoration technologies, inc. Slab restraint is typically caused by concrete or masonry walls that are connected at the perimeter of the structure. Posttension slab homes have a warning often stamped into concrete never to cut or drill. Any post tension slab inspectors out there i am building a new home in longview, texas, and they poured our post tension slab 7 days ago. When errors are made onsite during the posttensioning process, the ability of the reinforcement to prevent cracking is decreased. Cracking in groundsupported post tensioned slabs on.
Sdi is a nationally recognized leader in the repair and alteration of posttensioned concrete structures. Posttensioning actively loads the structure one of the main differences between a posttensioned beam or slab and a typical reinforced concrete element is that the strands drape or profile inside the concretetheir vertical location changes along the length of the member. Hello all, i would certainly appreciate some advice on a problem im facing. Cracks caused by the restraint to axial slab shortening rts cracks. We provide post tensioning cables that are utilized in commercial high rise buildings and parking structures. I had a call this morning from a prospective client who was concerned about cracks in the concrete foundation of the home they were building. A residential posttensioned concrete slab will typically be 8 inches thick and use 3000 psi concrete. The structural slab was not waterproofed before putting on the topping. Repairs to posttensioning tendons are necessary when existing tendons are damaged, corroded, cut, broken, or have lost their force. Foundation repair experts crack in slab foundation.
Construction of post tensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. Lots of cracks in new post tension slab inspectionnews. The presenter stated that cracking in concrete beams is. The best way to ensure this doesnt happen is to educate your construction teams on the best practices for. The use of post tension tendons allows the engineer to design for larger slab construction spans typically used in parking structures or high rise. Post tensioning utilizes concretes inherent compressive strength to construct slab onground foundations. Because of heavy traffic the topping slab is now cracking and allowing water to pass through and become trapped above the structural slab. All concrete will shrink during the curing process which lasts up to a year after the time concrete is placed in the forms. Eruption of pt tendons caused by corrosion failure early commercially available unbonded post tensioning systems were susceptible to corrosion including paper wrapped, plastic pushthrough stuffed and heatsealed cigarette wrapped sheathing systems due to their susceptibility to the ingress of water. Shrinkage cracks in poured concrete are easily recognizable and can be distinguished from other types of cracks that occur later in the life of a foundation wall or floor slab the photograph of cracks above were taken of shrinkage cracks in a concrete slab floor in a home built in 2006. Shrinkage crack considerations for posttensioned foundations.
Avoiding posttension errors which result in cracking. Sep 09, 2019 foundation repair contractors concrete repairman takes pride performing warrantied quality stem walls repairs. If there are cracks, they should be hairline cracks only. We specialize in slab on ground foundations for residential.
Mesa arizona foundation repair contractors concrete repairman llc repairs, fixes, resurfaces, stem walls, post tension foundations, slab stitching, crack stitching for commercial foundations, residential concrete foundations and are local licensed foundation contractors. Our future vision pti envisions a future in which posttensioning is the first choice for reinforcing all structures. With over 20 years of experience as a post tensioning system supplier and installation contractor, sdi has both the technical proficiency and practical knowhow to perform any repair or retrofit operation. This section focuses on the repair and replacement of damaged unbonded tendons. Advantages of using posttensioning for your next repair, rehabilitation and. Construction of posttensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. In order to ensure that the posttension slab used will have the best chance of avoiding cracking, as well as ensuring the longevity of post tension slabs, there are several possible errors to consider. Can a posttension slab in dfw homes since mid 1990s be cut for under slab repairs. One of the expert building restoration services that we offer is post tension repair. Post tension introduces an external compressive force into the concrete before the foundation experiences soil induced movements. This means the foundation is reinforced by cables laid in a grid arrangement and tensioned after the concrete cures sufficiently with the intent to create compression in the foundation concrete to resist cracking. The tendon is a seven wire strand with an ultimate tensile strength of 270,000 psi. Windows and doors were being replaced in an owners condo in a mid rise building. Foundation crack repairs corner cracks almost every house in the houston area with a concrete slab has them.
These categories of cracks are caused by entirely different phenomena and have very different characteristics. Cracks caused by applied loads flexural or shear cracks. Intermittent concrete keys were specified to transfer slab shear forces from one side of the construction joint to the other. Almost all of the cracks found at the corners of the foundation are not a concern for foundation failure. Post tension slab eliminating cracks and joints in. Customer satisfaction is important to us, and we take pride in providing the best service. At granite, we perform slab foundation repairs as well as pier and beam foundation repairs.
Preventing cracks on posttensioned concrete slabs pro builder. Once the concrete has gained strength to 2000 psi, typically within the 3 to 10 days recommended by pti, the tendons are stressed. Most often the cracks extend across the entire foundation and occur prior to tensioning of the tendon cables. For instance, sps crack injection repair is most effective in restoring concrete monolithically with adhesive. No risk of cutting a posttensioned cable in the slab foundations of most dfw homes built since the mid 1990s. Rebar reinforcement in this case is technically allowed by code but in our experience, a properly designed posttensioned concrete slab will minimize cracking due to shrinkage.
The best way to ensure this doesnt happen is to educate your construction teams on the best practices for designing and constructing posttensioned slabs. Sealing cracks in posttensioned deck concrete construction. We offer structural concrete, tiltup, posttension slabs, and flatwork. Concrete repair expert james belville will take the time to fully explain the nature of your homes foundation problem. Preventing cracks on posttensioned concrete slabs pro.
Posttensioning institute education pt applications repair. In this blog, we will discuss low cost repairs homeowners can make for foundation cracks and exposed posttension cable ends. I suppose this is not unusual, based on other posts ive read. At granite, we perform slab foundation repairs as well as pier and beam foundation repairs a concrete slab foundation problem needs prompt evaluation and. By the third day, i noticed a crack in the back patio, and by the fourth, there were sprawling cracks throughout the entire foundation. If the edge of the slab is 50 feet away from the nearest shear wall, when post tensioned this edge will move in about. A similar slab crack is also commonly seen at a distance of. In the end, the cost will be worth it because your property will be safe and marketable. I am as you can tell not experienced with posttension concrete and i am planning on teaming up with someone who does, but i just wanted to get a head start and find out some thoughts about this. Posttension introduces an external compressive force into the concrete before the foundation experiences soil induced movements. Removing the interior floor finishes to make repairs to the slab is both expensive and time. As part of a proactive effort, the owner selected the investigatedesignbuild idb team led by structural and structural technologies to provide assessment, engineering and solution implementation for the parking structure.
The lobby level of the garage has a 4inch topping on a 10inch post tensioned slab with post tensioned beams spaced at 27 feet. In order to ensure that the post tension slab used will have the best chance of avoiding cracking, as well as ensuring the longevity of post tension slabs, there are several possible errors to consider. If the cost of foundation repair seems high at first, keep in mind that your home is a big investment. Concrete delamination repairs are completed at the same time. The foundation in question was a posttension cable reinforced foundation as opposed to a foundation which is reinforced with steel rebar see the typical photograph in this article. This article describes methods for repair of cracks that occur in poured concrete slabs or floors and explains the need for accurate crack cause diagnosis and impact on structure before repairs are attempted.
A post tension slab will usually have a stamp located by the garage entry either just inside the garage door our just outside the garage door. Concrete repairman foundation repair with quality grout, cement mixes for high quality repairs for your foundation repair mesa. Im adding more comments as i see issues in search inquiries. The final stress force indicated is 60% x 270 ksi x. In the united states approximately 60% of homes are built on soils with some clay content. Cables are arranged as indicated by the engineer and chaired to run through the center of the slab. For residential construction, tendons at 48 inches on center are common. Posttensioned foundation a typical posttensioned foundation with the forms set and ready for concrete.
Shrinkage crack considerations for posttensioned foundations june 1, 2015 shrinkage cracks in concrete slabonground foundations are a significant public relations problem to home builders. Having all the facts before you begin repairs will help you choose the right company and avoid unexpected cost and delays. Tulsa home builders 918 6885660 can a post tension slab have. Defects such as slab cracks can be costly to repair after construction. We have the equipment and know how to make your project successful. Pdf on mar 7, 2018, julio johan saire yanez and others published chapter v. With over 20 years of experience as a posttensioning system supplier and installation contractor, sdi has both the technical proficiency and practical knowhow to perform any repair or retrofit operation. We have an established reputation for being leaders innovation, determining creative solutions for complex problems. These steel cables, tensioned during original construction prior to removal of the forms, provide critical support to the concrete, both stabilizing the material and providing necessary weight distribution. Posttensioning utilizes concretes inherent compressive strength to construct slabonground foundations. If there arent many cracks in the posttensioned slab and you have good reason. The builder used a posttension foundation with footings. This posttension slab see crisscrossed cables is ready for cement to be poured.
Aug 14, 2012 windows and doors were being replaced in an owners condo in a mid rise building. Since the early 1950s, post tension tendons have been used in the design of concrete structures. If a garage has a post tension slab there is usually either a sign stamped in the concrete floor saying it is a post tension slab or a plastic sign on the garage wall stating its a post tension slab. Many people dont understand how they work and the benefits. Eruption of pt tendons caused by corrosion failure early commercially available unbonded posttensioning systems were susceptible to corrosion including paper wrapped, plastic pushthrough stuffed and heatsealed cigarette wrapped sheathing systems due to their susceptibility to the ingress of water. M onolithic post tension, foundation settlement, heave crack stitching, floor leveling, concrete grinding and much more.
Because all shaw homes slabs are posttension concrete, cracks are. Mar 09, 2020 as a result, even though posttensioning is meant to help prevent a slab from cracking, the slab can still crack if the tensioning process is done incorrectly. Significant overbalancing of the weight of the concrete with posttensioning can actually lift and crack the slab. If each panel contained one crack that was fullpanel lengthabout 15 ft the total crack length for the 100,000 ft2 floor would be 210 lineal ft. Post tension slabs superior foundations services jackson.
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