Short wave infrared hyperspectral imaging based procedures for quality control of recycled aggregates from end-of-life concrete

To answer to the market requirements, recycled aggregates must be competitive with natural aggregates, in terms of physical-mechanical characteristics influencing the workability, compressive strength and durability of the new concrete (Arasan et al., 2010). More in detail, the presence of contaminants such as plastic, brick, gypsum, wood, etc. have to be absent or below limits determined by law and recycled aggregates have to be liberated from mortar paste.
In the last years, in order to provide sustainable solutions able to combine the need of raw materials with waste reduction, many efforts have been addressed to develop, set-up and apply innovative technologies and approaches to maximize DW conversion into secondary raw materials. In this perspective, the realization of a suitable sensor technology able to identify the presence of pollutant materials and to detect the degree of liberation of recycled aggregates in the output of a DW recycling plant can play a key role for quality control purposes. To reach this goal, a HyperSpectral Imaging (HSI) system can be adopted in order to perform non-destructive and rapid analyses. In this work, the utilization of a HSI sensor working in the short-wave infrared (SWIR: 1000-2500 nm) range to check the quality of the output stream, resulting from a DW recycling plant, was investigated.