LIBS-RFID-based quality monitoring system LIBS:



To close the loop of concrete waste and to implement circular economy, it is necessary that the value in materials/products is retained as long as possible. To achieve this, innovative recycling technologies that can separate concrete waste into its various components (e.g., aggregates and minerals) play a crucial role, but they are not enough to bring the recycled materials (secondary raw materials) on the market. The replacement of virgin aggregates is hampered because the industry is hesitant to replace primary with secondary raw materials. The industry perceives recycled material to be subject to high variability in quality. There is a high cost associated with determining the usability of a recycled product, which is intended to replace virgin feedstock for the manufacture of concrete. Therefore, to effectively achieve circularity, it is also necessary to make sure that the product satisfies industry’s needs by measuring the quality and by explicitly displaying the quality of the products (recycled aggregates).

Figure 5. The LIBS-based quality assessment system.

To remove this bottleneck, C2CA Technology designed a system (patented) through which the aggregate quality can be assessed and then traced throughout the value chain.

The system is made of an in-line Laser-Induced Breakdown Spectroscopy (LIBS)[1] -based online sensor system that can continuously measure and control the quality and homogeneity of the aggregates produced by the ADR (5000-10000 chemometric analyses per ton) (see Figure 5).

[1] LIBS is a plasma emission spectroscopic technique where the spectrum is representative of the elemental composition of the material and also highly characteristic for the material type in case of fingerprinting.

The LIBS-based equipment is coupled with a contactless identification and tracking system based on RFID sensors and a large cloud database. The tags store the information about quality received from the LIBS system and link it with the large cloud databases. Each separate fraction of the product holds a dedicated information carrier, which contains the information of the fraction being assessed by the LIBS-based system. Therefore, the identification process does solve the quality assurance problem since the labels correspond to the material they are included in. This increases the transparency of the recycled product and provides a reliable and easy way to access information defining such recycled products and the parties involved that handle the demolished concrete and the recycled products. The data can thus relate to quality, properties of the demolished concrete, manner of demolishing, original application and location of the demolished concrete, method of transportation, owner of the original building, demolition firm, etc. Besides, the information can help users of the product to design an optimal recipe for new concrete, including, e.g., the amount of cement, water, superplasticizer that is to be added to the recycled product, taking into account the quality of the recycled product and the intended application of the new concrete. The dedicated RFID information carriers are easily noticeable by cost-effective RFID readers, and their presence can thus be established even if the tags are not visible and embedded in the recycled or final product (see Figure 6).

Figure 6. The RFID reader and writer system (left). RFID embedded in concrete (right).


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