Environmental performance of construction and demolition waste management strategies for valorization of recycled coarse aggregate.

This study reports on a Life Cycle Assessment (LCA) comparison between two different Construction and Demolition Waste (CDW) management strategies to produce Recycled Coarse Aggregate (RCA): the current recycling strategy (RCA-C) versus air jig strategy (RCA-PR). Additionally, RCAs are compared to natural aggregate production. Air jig is proposed as a recycling strategy for CDW sustainable reuse and recycling. In contrast to RCA-C, air jig allows better CDW segregation, providing recycled materials with better quality. The results point out that recycling strategies differ in segregation efficiency, the quality of recycled material produced, and environmental performance. Both recycling strategies provided environmental benefits when compared to natural aggregate. RCA-PR presents better environmental performance due to the larger number of by-products generated as a result of using air jig and it is able to reduce the environmental impacts related to its management based on the benefits of its by-products. The results suggest that the production and transport of RCA are viable from an environmental point of view in larger urban centers. This study provides a better understanding of CDW management, enhancing knowledge on the environmental performance of the current practice and a future proposal recycling strategy. Moreover, it opens up a new perspective on the multifunctionality associated with recycling strategies of CDW and understanding about air jig environmental impacts.

Optimization and dust emissions analysis of the air jigging technology applied to the recycling of construction and demolition waste.

This work aims to evaluate the use of the air jigging technique, a density-based separation technology commonly applied in mineral processing, to upgrade the quality of mixtures (density and geometric properties) that represents the typical composition of construction and demolition waste (CDW) produced in Brazil. In this sense, tests involving the variation of the main operational parameters of jigging (bed expansion rate, pulsation frequency and jigging time) were carried out aiming to find those which provided the best recycled aggregates quality after processing. Also, fines and dust emissions generation during jigging were measured in order to estimate their potential impacts on human health and environment. The results showed that the air jigging process is adequate to improve the quality of CDW by increasing the concrete concentration in the dense product. The use of high bed expansion rates showed to be of major importance to decrease the content of ceramic aggregates in the dense product, allowing obtaining products richer in concrete. Also, the measured properties of the obtained aggregates (size distribution, shape, etc) met the usual standards required for natural aggregates. Finally, material losses and dust emissions generated were negligible in comparison to the total mass processed, although special attention must be given to safety measures due the presence of inhalable particles (<10 µm).