Embedding NFC Tags into 3DCP Elements (2024-09)¶

3D Concrete Printing (3DCP) represents a paradigm shift in the methods for concrete construction, offering labour automation, reduced material usage and waste, and extended design flexibility. 3DCP also enforces an inherent digitalisation, facilitating interaction among various stakeholders. This requires integrating the printed elements into the digitalised workflows that support the logistics of the process. This research project examines the potential of incorporating Near Field Communication (NFC) tags into 3DCP elements to facilitate their integration into digital workflows. NFC is a subset of RFID technology designed for short-range (< 100 mm) secure data exchange. The ability to embed tags directly between layers during the 3DCP process enables a broad range of functionalities, including element identification, dynamic data flow between physical elements and their digital twins, supports the development of material passports, and provides guidance for assembly or systems installations. Material passports are comprehensive digital datasets documenting the essential attributes of building materials and components, including their origin, composition, environmental impact, and potential for reuse [1]. They are key to implementing circular economies into the built environment. Previous studies on tracking technologies [2] have identified NFC as the lowest threshold for implementation due to the low cost of the tags and the widespread availability of NFC readers in most smartphones. This study assessed the feasibility of integrating NFC technology into 3DCP elements, by testing optimal placements for printing operations and accessibility. Prototypes were printed using a 3DCP system based on a robotic arm with a 20 mm nozzle and a 10 mm layer height. In this study, two types of NTAG213 [3] were selected for testing: a standard version measuring 25 mm in diameter and a ‘micro’ version with a diameter of 8 mm. Different placement strategies were tested to determine the most suitable location of NFC tags within 3DCP elements. NFC tags were placed between the two last layers to be read from the top or bottom of the part or between two arbitrary layers to be read from the front. Additionally, three different embedding techniques were tested for fixing the tags during the printing process: (a) placing the tag directly between layers, (b) using a holder to support the tag parallel to the printing layers, and © a holder that orients the tag vertically. The readability of the embedding approaches are summarised in Fig. 1. Immediately after printing all tags were unreadable. However, after removing the plastic cover and allowing the part to dry for a day, the tags were functional again, as reported in previous research [2]. One layer (10 mm) was the maximum reading distance for 25 mm tags from the top/bottom, while 8mm tags were only readable from the front face of the element when secured with holders (positions b and c). Embedding NFCs during the printing process proves to be a simple procedure that is compatible with most printing processes. The use of customised holders facilitates the correct placement of tags and allows them to be replaced if necessary. On the other hand, embedded tags can provide secure storage for sensitive information. The tests show that NFC tags can be easily integrated into the 3DCP process by placing them between layers. Although this process depends on manual placement, it can be further automated into in-line placement systems. NFC technology has demonstrated significant potential to enhance data management and accessibility within the construction industry, especially in the use of 3DCP in prefabrication. The functionality of the tags has been tested for several months. While these results demonstrate the feasibility of the method, further prototypes and pilots are needed to validate the long-term reliability of these devices in field applications.