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This work deals with the separation of concrete, brick and gypsum particles from a CDW recycled aggregate mixture. Construction and Demolition Waste materials can be handled as an ore treatment problem. Efficient sorting processes of low quality CDW recycled aggregate could allow the reuse of concrete, brick and gypsum particles. The processes also improve the remaining mixed aggregates for recycling in unbound sub-base materials, by increasing their self-cementing properties and by reducing the sulfate content through the removal of gypsum. All tests were carried out in the size range between 4 and 20 mm using a laboratory air jig. The aim of the work is to concentrate a high amount of gypsum (light material) and concrete (heavy material) particles. Three working parameters are relevant for the jigging processes control such as the sorting duration, the frequency and the expansion ratio. Each of them are studied. It was found that a quadratic model of the number of jig cycles, a product of the frequency and time, accurately predict well the sorting results, if the expansion is large enough. An optimal point seems achieved at about 320 jigging cycles. Concentrates with concrete contents higher than 90% and gypsum contents significantly lower than 1% were possible to be reached and can be an alternative in aggregates for the concrete market. Indeed, gypsum reduction in concrete concentrates was about 25 times. This level of reduction could be satisfactory in sorting real demolition products. On the other hand, contents of over 70% of gypsum concentrates were obtained, increasing the reuse and recycling abilities.

The recycling of inert construction and demolition materials (C&D) remains problematic if these materials are used to process high-quality recycled aggregates suitable for manufacturing new concrete. Even when selective demolition is employed, the crushing and classification of C&D produces recycled aggregates with an unacceptable level of impurities, with the content of gypsum being the biggest concern. Another concern is the percentage of brick content that decreases the density of the recycled aggregate as well as its homogeneity. The present work studies an air jig sorting method to separate out concrete particles from a C&D mixture that contains high amount of gypsum (22% mass) and brick (24% mass) particles. The mixture of aggregates studied had a 4–20 mm grading. After sorting, the bottom third of the mixture had less than 1% mass of gypsum and more than 90% mass of concrete particles. In contrast, the upper third of the sorted material contained gypsum in proportion of nearly 80% mass. The separation mechanism appears to be governed by both particle density and bulk density of individual components. These results are very encouraging and prove that the air jigging method is a promising technology for the use in C&D recycling plants. Further research is warranted.