The Elop Insight technique

The most commonly used technologies in concrete construction for long span lengths, such as bridges, or for thin slabs, are reinforced concrete and pre-stressed concrete. In both cases, strengthening is done with the implementation of steel elements: reinforcement with steel rods in the former and tendons in the latter.

A decrease in strength, and therefore maximum carried load, is generally caused by deterioration of the concrete material or corrosion of the steel elements. There are numerous reasons for aging of concrete constructions, such as construction faults, conditions of usage, quality of materials, and environmental conditions.

These conditions can be roughly divided into mechanical, chemical, and physical factors, for example fatigue, impact, overload, alkali silica reactions, shrinkage, and freeze-thaw cycles. Corrosion in steel is most often related to carbonation of concrete or chloride introduced corrosion due to de-icing salts or salts from the ocean.

Defects emerging on the surface can be easily identified by visual inspection, but the flaws inside a structure need more advanced methods to be revealed.

A structure is built with a fundamental performance requirement for a minimum period, as defined by the client. Performance can be related to structural safety, load carrying capacity, serviceability, durability and more. Over time the structure might degrade and eventually reach the lowest acceptable performance where repair is needed.

The remaining life of the repaired structure depends on life strategies, budget, but also on correct assessment. Choosing the wrong repair measure or basing the strategy on inferior assessment can even make the life of the repaired structure very short.

Concrete structures, and in particular bridges, need to be inspected regularly to meet the safety and accessibility requirements of users. To be the most efficient from a client and cost perspective, assessment should guide maintenance, repair and strengthening strategy.

Even though there is no single standard procedure that every NDT inspector should follow, the usual assessment strategy should follow a three-level principle.

Besides the investigation of chemical composition that enables us to conclude the degree of erosion, it is important to scrutinize the interior of the structure for the sake of comprehensive understanding.

Elop's vision is to provide asset owners with smart products and solutions that help improve safety, extend lifetime, minimize lifecycle cost, and contribute to an overall reduction in the environmental footprint of concrete structures globally.

As the built infrastructure gets older, the need for thorough assessment and understanding of deterioration process and its influence on building safety increases. The basis for efficient lifecycle management is to know its status, what is managed, whether the facility meets safety requirements, and what it costs to remedy identified problems.

In particular, for concrete structures, such information is not possible to gain without in-depth NDT evaluation. Elop has developed a new groundbreaking solution enabling accurate inspection, asset management, and structural health monitoring of concrete structures - the Elop Insight.

The Elop Insight scanner rolls over the surface to be investigated, and a 3D scan of the interior structure is generated in real-time. Thanks to ultrasonic technology, it can accurately identify the size and depth of existing defects within concrete structures including voids, honeycombs, delamination, air pockets, and internal cracking.

The methodology follows a typical assessment procedure, but is characterized by significantly shorter time-to-result whilst maintaining higher accuracy compared to other techniques and methods supported by devices available on the market.

While the scanner rolls over the surface, ultrasonic waves are sent through the material, reflected at the interfaces between the concrete and empty spaces within the structure, and received back by the receiving transducers. With the use of the Synthetic Aperture Focusing Technique, the 3D live image of the interior structure is reconstructed.

Immediate cloud sharing capabilities allow for remote team support when needed. A fully digital workflow eliminates unnecessary manual steps, increasing productivity, efficiency, and completeness of the overall process.

The strong focus of the Elop team has been to deliver the best thought through and most pragmatic solution for NDT inspections, bringing a series of advantages that make Elop Insight a solution of unparalleled effectiveness.

The following can be listed among the most important advantages.

Voids and delamination on a wall structure. An assessment of precast element working as formwork for in situ cast concrete was carried out after a larger void had been found when drilling was made for fasteners.

In the assessment, the following methodology was followed:

• Overall visual inspection studying of documents and planning
• Simple investigation with both Impact Echo and Ultra Pulse Echo to calibrate and investigate best strategies
• Dividing areas into sufficient small squares, but not too small due to time limitations. Here 250 x 250 mm was a good compromise
• Using Impact Echo to detect possible flaws in the concrete elements
• Using Elop Insight for more detailed investigation
• Verifying results with Endoscope

In total 85% of 3,000 m2 wall area was examined.

Large areas were found with delamination or honeycombing between the precast elements and the in-situ cast concrete. However, the size of the defects was small and the existing steel reinforcement was to a major extent covered by concrete. The reason for debonding was most likely ice in the formwork, shrinkage of the in-situ concrete, temperature effects, or a combination of these factors.

The newly developed ultrasound scanner and cloud-based software, Elop Insight, is one of the most advanced and versatile devices on the market, allowing users to detect and visualise air pockets and voids within concrete structures.

Here are a couple of points that need to be stressed:

• Such a high-tech, future-orientated device will not replace the expertise, knowledge, and hard work that every NDT inspector puts into the job. It helps make the work more efficient, comprehensive, and meaningful.
• Every asset inspection still needs a multi-angular, comprehensive approach, but using Elop Insight it can be optimized, focusing on correct diagnosis whilst minimizing time and effort on auxiliary activities such as reporting and data organization.
• NDT inspection is invaluable for built infrastructure and needs to be esteemed by the knowledge and expertise, not the hours spent onsite. Elop is committed to improving productivity at every possible step through smart software solutions.
• Elop Insight simplifies the overall assessment. NDT evaluation may be complex, but it does not have to be complicated. The direct 3D live visualisation of the interior structure helps data interpretation and productivity.
• As one size does not fit all, one technology will not be the answer to everything. However, Elop Insight is proven to be unmatched when it comes to the detection and visualisation of voids, air pockets, or honeycombing within the concrete structure.

Convenient and well-thought-through cloud data storage with access through the web portal interface makes it a strong tool not only for one asset but as part of a broader asset management system.

Summarising, bulletproof technology incorporated into a bulletproof solution allows users to get bulletproof data leading to bulletproof conclusions.