Ground penetrating radar (GPR) is a technological method of creating ground or soil cross-sectional profile in a non-destructive way; without drilling, digging, or breaking the surface. Ground penetrating radar surveys can be carried out using a GPR cart pushed along the ground surface, an ATV (All-terrain vehicle), or a truck-mounted configuration that penetrates the soil.
GPR can also distinguish material layers and determine specific properties of the materials, such as dielectric constants and electromagnetic wave conductivity. This article will explain how GPR can be used to improve road conditions and also previous tests to ascertain this claim.
Table of Contents
How does a Ground Penetrating Radar System Work?
Ground penetrating radar (ground radar) works by sending pulses of ultrahigh-frequency radio waves (microwave electromagnetic energy) into the ground via a transducer (also called an antenna). Either by hand or behind an ATV or vehicle, the GPR antenna (transducer) is pulled along the ground. The energy transmitted is reflected by different buried objects or other materials under the surface of the Earth.
The antenna receives the reflected waves and stores them in the digital control unit. This control unit compares the reflections to the two-way travel time in nanoseconds before amplifying the signals. The digital control unit plots the output signal voltage peaks on the GPR profile as different color bands.
How GPR can Improve the Condition of Existing Roads
GPR is the fastest non-destructive way to check and analyze bridge decks. It is an excellent way to figure out what kind of damage needs to be fixed.
GPR scans can help you see if the concrete is getting weaker. GPR scan will reveal the damage of these points compared to the areas that are still in good condition. These findings can be improved and confirmed with more tests like measuring chloride and ion concentrations by taking core samples. GPR can look at specific parts of the structure that need to be fixed and figure out how to replace rebar and concrete correctly. Unless they use GPR, engineers often don’t know where to start drilling or cutting.
All kinds of structural assessment projects need a wide range of GPR frequency to look for damage and integrity at different resolutions. For example, you need low-frequency signals to get deeper into the ground and high-frequency signals to get a better scan picture.
To get the most accurate structural assessment data, it’s best to use a mix of frequencies. This will give you a lot more resolution and depth. It takes one frequency to get one set of data, and so on. Using a multi-frequency subsurface imaging system allows you to look at your findings differently.
How GPR can Improve the Condition of Newly Planned Roads
Environmental scientists use ground penetrating radar (GPR) to get pictures of the ground below before construction. This first assessment helps to predict the life span of the road and as well determine materials to use. In addition to protecting local ecosystems and the planet as a whole, this also helps know the soil composition.
GPR gives people the ability to do something about the environment before it’s too late. With this system, you can look for contamination risks and keep an eye on them without breaking ground. This way, you save time and get important information. Unlike traditional locating equipment, GPR can see everything below the surface including water tables, non-conductive buried objects, changes in soil structure, and more.
A lot of the time, environmental problems are not noticed on the surface. Buried contamination could harm the environment’s plants, animals, and even future construction.
After a scan, the ground penetrating radar system can show what it found, and the operator can use GPS software to map the findings and look at them in more detail. This allows for more precise digging and minor damage to the soil and the plants and animals around it.
Effectiveness of GPR on Road System Conclusion
- The University of Nebraska – Lincoln research on “use of ground penetrating radar for construction quality assurance of concrete pavement” in 2009: The study concluded that GPR is an excellent way to measure concrete pavement thickness. Data analysis can be done in less than ten minutes per scan. For example, each location in a grid scan can be done in less than five minutes.
- The Korean Research Institute study on “Application and the Limitations of GPR Investigation on Underground Survey of the Korean Expressways” in 2021: The study concluded that 3D GPR, like the multichannel GPR, can combine the plan view by depth, cross- and longitudinal sections making analysis more straightforward and accurate.
Why Use Ground Penetrating Radar in Road Maintenance?
Concrete and other materials made by humans, like asphalt, are used a lot in construction. Using GPR is a non-destructive way to scan these materials that can be pierced before cutting, drilling, or performing other non-destructive tests. Quantitative data is used to make intelligent decisions about the condition and integrity of infrastructure assets that are old or new.
GPR data is used on a regular basis to help people decide what repairs or renovations should be done first and how important they are. GPR can see into a structure and give accurate information about the orientation and depth of subsurface features and objects. This is a big advantage over the traditional manual and visual inspection methods.
Here are a few of the advantages and benefits of using GPR to scan concrete
- Image Accuracy – GPR has the ability to look at slices at different depths, allowing them to tell you the depth and orientation of objects that are embedded in the ground.
- Efficiency – Even as the need for road construction and maintenance grows, the money to pay for them is hard to come by. Having the ability and reputation to do an excellent job without coming back or making mistakes is a significant advantage in the market. Being more effective is better than being speedy. If you have a professional-grade GPR tool, you can get this advantage.
- Integration of workflows – As a rule, big projects require service providers to be able to seamlessly fit into the work and manage the projects of their clients. In fact, they can become more competitive by offering ways to cut down on the time and money spent on more significant projects. For example, off-site reviewers can look at scanned results right away, cutting down on the time it takes to scan and cut. This can also help to avoid the need for a second site visit.
- Non-destructive – Non-invasive testing and assessment are always better than destructive testing, which is costly and harmful. The best way to save time and money, even if destructive testing or coring is required, is to target it to where it will be most beneficial.
- Difficult Places – They are small and can be used in any way on the floor. GPR sensors can also be used in tight spaces. GPR is very important because it is used from the surface. It can even tell if there are holes in the materials around it. Operators can map large areas quickly by putting the GPR sensor on a cart or a vehicle-towed platform and moving it around.
- Flexibility – GPR can be thought of as many different tools in one, and it gives its owners the chance to start new businesses and do new things. A sound GPR system can do everything from marking where you’re going to cut or drill to investigating structural components, providing due-diligence records, and figuring out how old the rebar is.
- Safety and Health – There are a lot of regulatory, financial, and social reasons to be concerned about workplace safety, and GPR is the best way to deal with these issues. GPR is not only safe for the infrastructure, but it is also safe for the people who use it and for the general public. You can use GPR in a public place without putting anyone else at risk.
- No Air and Noise Pollution – Another big problem with excavation is that it pollutes the air and makes a lot of noise. A lot of things can happen as a result of this, from environmental pollution to being sued by someone.
With GPR, you can’t hear it, which means it doesn’t bother people or the soil. GPR is great for cities where the comfort of the people who live there is important to the growth of the area.
Frequently Asked Questions
What is GPR and How Does It Work?
Each GPR system is equipped with one or more antennas capable of transmitting and receiving radio frequency waves. These radio waves penetrate the surface that the antenna is in contact with or is located near. While the majority of the signal evaporates, a portion of it returns to be received by the antenna. This return signal generates visual data that is recordable, and interpretable. The data is shown as images on a control device, allowing the operator to examine objects’ size and depths.
Is GPR capable of seeing through anything?
It is almost capable of doing this. Only radar is capable of detecting both conductive and non-conductive materials. While radar is capable of seeing through conductive materials such as metal and salt water, it cannot see inside them. Additionally, while fresh concrete is conductive, it becomes non-conductive as it cures.
How precise is GPR?
By and large, GPR reveals the horizontal positioning of targets in their specific places. However, various factors can affect the speed and precision with which depth readings are taken. These include, but are not limited to, soil type and moisture content.
The radar signal’s velocity depends on the composition of the substance being scanned and the target’s depth. For instance, the signal will travel slower through more difficult-to-penetrate soil types. Similarly, the distance between the antenna and its target is determined by the time required for the radar signal to be reflected off the target and back to the system.
Is GPR better than concrete X-ray scanning?
Both technologies have good and bad things about them. However, GPR is easier to use and comes at a better price. Let’s take a look at some of the advantages of using GPR instead of concrete scans:
- Real-time concrete scans
- A frugal concrete scanning option
- Better safety on the job and low noise production
- Improved accuracy with 3D scan results
What Can GPR Find?
US Radar GPR Systems are designed to detect material composition variations. They can be used to locate items whose compositions differ from their surroundings. For example, a PVC pipe is composed differently than the surrounding dirt. Similarly, filled-in voids and excavations will differ from the surrounding soil.
Here are some examples of items that GPR can assist you in locating.
- Utility Services: Clay Pipes, concrete Pipes, plastic/PVC pipes, transite pipes, missing valves, metal pipes, water boxes, illegal/unknown connections, abandoned lines, conduit, gas, water/wastewater, power, telecom wire, CATV, fiber optic, Voids, septic tanks, and manholes, and more
- Structure Analysis: Reinforcing, voids, cracking, slab/wall thickness, asphalt layer thickness, concrete sparling, and so on
- Environmental: buried Drums, Landfill Limits, and More
Are there any risks associated with GPR?
Many people wonder if the person utilizing GPR equipment is at risk, and the truth is that there is not. Despite the fact that “ground penetrating radar” may sound dangerous, it is an entirely safe method that only uses 1% of the power of a cell phone signal to operate.
