Post tension cable locators are critical for renovation projects and finding damaged cables within concrete structures. By using GPR technologies, we can provide high-resolution imaging of concrete to map out exactly where post tension cables are and evaluate if there are any failure points. This gives contractors the information they need to safely continue with a project or repair damage within a concrete structure.

What Are Post Tension Cables?

Post tension cables are an essential component of concrete structures. The cables are composed of high-strength steel wires within a plastic sheath, and they are embedded within concrete slabs. Once concrete is poured, the cables are tensioned to apply pressure to the concrete. A tendon is the term used to describe the assembly of the sheet, pre-stressing strand, anchorage, corrosion-inhibiting coating, and the grout around the steel wire or bar.

Post tension cables are used in many types of buildings and structures that have concrete. Some examples are apartment buildings, office buildings, slabs-on-ground, water tanks, and bridges. In today’s world, post tension cables are used in most aspects of construction.

Benefits of Post Tension Cables

Post tension cables are helpful for many reasons. When used in buildings, they allow for fewer beams, more slender elements, and thinner slabs. This enables slabs and beams to be continuous for longer distances. An example of this is having a single beam run from one end to another without needing to place beams between every column. Overall, this helps increase efficiency and reduces the amount of concrete required for building projects.

Increased Carrying Capacity

Reducing the amount of concrete required has several benefits. Primarily, this reduces the building’s weight and puts less load on the foundation. It also can reduce the overall building height without affecting the floor height. A lower building weight and height can save costs on facades and mechanical systems. Additionally, when there is continuous stress and elongation of the post tension cables, a compressive force is applied to the concrete. This compression helps counter the tensile forces from the load. Ultimately, the load carrying capacity of the structure increases when post tension cable systems are used.

Types of Post Tension Cables

The two main types of post tension cables are unbonded and bonded. Unbonded tendons are typically laid out based on installation drawings, and concrete is poured over them at the desired strength. Then, tension is applied to the tendons and they are anchored. The anchorages are essential to prevent the tendons from returning to their original length.

Why Use Post Tension Cable Locators?

When a structure or object has post tension cables, it is critical to locate the cables before renovations and repairs. The cables are kept at a very high tension, and cutting them can compromise the integrity of the structure. Additionally, cables can become damaged within concrete. In these cases, post tension cable locators are used to locate areas of probable cable failure and determine continuity. These insights can give contractors and construction workers the information needed to properly repair a structure and keep it safe for the public.

GPR Provides High-Quality Concrete Images

Ground penetrating radar, commonly known as GPR, is a technology used for high-resolution scanning and imaging of concrete. It’s often used to determine the locations of embedded materials, such as rebar and post tension cables. Using GPR technologies, GPR Data can provide high-quality 2D and 3D images of what lies within the concrete or beneath it. These images can be analyzed to determine any damaged materials, weak points, or simply to know where these materials are in the case of drilling, cutting, coring, or demoing.

Why Use GPR for Post Tension Cable Locators?

GPR is a cost-effective and highly accurate tool for finding out where post tension cables are and for determining whether they are intact. Using GPR, we can locate terminal ends and attached add-on cables, and we can map out where the cables run within the concrete.

What Are the Benefits of Using GPR over X-Ray?

GPR technologies are not the only type of post tension cable locators used in the construction industry. X-ray technologies can also be used to scan concrete for embedded materials. However, using x-ray has several drawbacks. First, x-ray relies on radioactive sources. This means that x-ray emits more radiation than GPR during use and can pose a hazard to construction workers. In contrast to this, GPR uses electromagnetic energy and can safely be used while construction sites are open. Additionally, GPR yields higher quality and higher-resolution images with more accurate depth reporting and 3D mapping than x-ray imaging.

When Should GPR Post Tension Cable Locators Be Used?

Post tension cable locators are important during different stages in many different projects involving concrete. For renovations and remodels, GPR can provide the necessary documentation to know exactly where post tension cables run. This is especially important for historic or older buildings that lack documentation. Post tension cable locators are also critical to determine the condition of cables within a structure.

In a past project, we used GPR to determine if there were failure points in the post tension cable system of a high-traffic parking garage. GPR can be applied near specific points in a structure, such as where concrete is cracked or rebar is visible to investigate potential points of failure. The reports generated by GPR can be used to determine if a cable bundle is damaged and to pinpoint exactly where that damage is on an x,y,z axis.

How Are GPR Reports Helpful?

Using GPR, we can generate high-quality three-dimensional data grids and line scans that can be used immediately and referenced in the long term. In our project inspecting the post tension cables in a high-traffic parking garage, we did line scans to rapidly trace and follow out cables. This provided a clear image of the layout of the post tension cables in real time. We also created data grids that provided 3D depth-slice information about problem areas. Using this x,y,z positioning report, we were able to determine what areas were cable failure points.

What Else Can GPR Do?

Aside from being used as post tension cable locators, GPR is helpful in many other applications of concrete imaging. The first of these is rebar mapping. GPR can be used to map out rebar and assist in structural evaluations for designing and renovating structures. Along the lines of structural evaluations, GPR condition assessments of concrete can be used to find deterioration and settlement voiding, and to detect delaminations. This can aid contractors in evaluating the scope of remediation projects. In all types of concrete imaging with GPR, we can provide high-resolution imaging and 3D maps, 2D or 3D AutoCAD drawings, and image reports that are easy to understand and use.

Contact GPR Data for Post Tension Cable Locating

When it comes to post tension cable locators, GPR is the leading technology for good reason. With GPR, we provide high-resolution 2D and 3D reports that can be used to map out post tension cables and analyze their condition. From offices and apartment buildings to parking garages and bridges, GPR Data can provide all the information you need to continue safely and on your project. Get started by requesting a quote or giving us a call at 541-345-1075 today.