DNP Develops Crack Detection System of Deteriorating Concrete Structures Including Tunnels
Employs sheet-based RFID IC tag and accurately detects crack expansion
Dai Nippon Printing Co., Ltd. (DNP) has developed a testing system to detect spread in decrepit concrete cracking in tunnels, bridges and others.
Much of Japan's social infrastructure-related construction, including tunnels and bridges, was performed during the period of high economic growth; from approximately 1954 to 1973. In recent years, however, these structures have been allowed to age, and cracked and falling concrete has become a social problem. Local authorities and operators are legally obligated to perform periodic checks, but at the same time, this requires skilled workers using expensive equipment in order to ascertain the status of the underlying concrete. And the resultant costs and lack of adequately trained personnel have become a challenge. In order to overcome this challenge, DNP has developed a film sheet format testing system based on a Radio Frequency Identifier (RFID) IC tag that detects spread in concrete cracking in a simple manner,
The newly developed system employs a testing sheet with a built-in passive IC tag that is activated by external radio waves. The sheet is applied to spots where micro-cracks have emerged on the surface of the concrete, and which are deemed likely to reduce the functionality of the structure at some point in the future, and therefore, require monitoring. By way of example, according to periodic testing guidelines for cracking in road tunnels laid down by the Ministry of Land, Infrastructure, Transport and Tourism, if cracking expands by in excess of 3mm then early repairs are needed.
The newly developed sheet detects the progress of cracking via break in the pattern circuit.
The features of the newly developed sheet are as follows;
- A dedicated UHF band-responsive reader-writer is capable of reading off information from multiple sheets collectively, facilitating inspection work efficiencies.
- The crack detection sheet is not battery-driven, and therefore requires no exchange of batteries. And as the sheet uses a long distance UHF band IC tag, it is possible to perform read-offs at a distance of several meters.
- As it is possible to perform read-offs for cracking in a simple manner even in locations that are difficult to confirm by sight, oversights and omissions can be avoided. Cracking of even just several millimeters can be detected by waving the reader-writer over the spot in question. No special skill is required, and workers can accurately perform the required testing. Data obtained by the reader-writer can be transferred to a computer allowing for the creation of testing logs in a simple manner
- The cracking testing sheet also employs a unique adhesive material, also developed by DNP, which hardens when exposed to ultraviolet light from the sun or fluorescent lighting.
DNP will conduct field tests and marketing using the newly developed system, aiming for commercialization in spring 2018.