The potential of using air jigging to sort recycled aggregates

• Published in: Journal of cleaner production Vol. 66; no. 66; pp. 46 - 53
• Main Authors: Cazacliu, Bogdan, Sampaio, Carlos Hoffmann, Miltzarek, Gerson, Petter, Carlos, Le Guen, Lauredan, Paranhos, Régis, Huchet, Florian, Kirchheim, Ana Paula
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-03-2014; Elsevier
• Subjects: Aggregates; Air jig; Animal, plant and microbial ecology; Applied ecology; Applied sciences; Biological and medical sciences; Brick; Conservation, protection and management of environment and wildlife; Density; Engineering Sciences; Environment and sustainable development; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gypsum; Materials; Materials selection; Pollution; Recycled; Recycled aggregate concrete; Recycled concrete aggregates; Recycling; Sorting; Sorting by density; Gypsum; Air jig; Recycled aggregate concrete; Sorting by density; Recycled concrete aggregates; Pollution prevention; Density; Sustainable development; Sorting; Concrete; Recycled material; Recycling; Environmental protection; GRANULAT; BETON; GYPSE; DENSITE; RECYCLAGE DES MATERIAUX
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2013.11.057

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.
•Sorting the recycled aggregates (RA) may improve the quality of this material.•Air jig prospective test on RA provided better results than previous wet jig tests.•RA resulting from the jigging are of suitable quality to be used for secondary concrete.•Both particle density and bulk density govern the separation process.