This study aimed to investigate the recycling opportunities for industrial byproducts and their contribution to innovative concrete manufacturing processes. The attention was mainly focused on municipal solid waste incineration fly ash (MSWI-FA) and its employment, after a washing pre-treatment, as the main component in artificially manufactured aggregates containing cement and ground granulated blast furnace slag (GGBFS) in different percentages. The produced aggregates were used to produce lightweight concrete (LWC) containing both artificial aggregates only and artificial aggregates mixed with a relatively small percentage of recycled polyethylene terephthalate (PET) in the sand form. Thereby, the possibility of producing concrete with good mechanical properties and enhanced thermal properties was investigated through effective PET reuse with beneficial impacts on the thermal insulation of structures. Based on the obtained results, the samples containing artificial aggregates had lower compressive strength (up to 30%) but better thermal performance (up to 25%) with respect to the reference sample made from natural aggregates. Moreover, substituting 10% of recycled aggregates with PET led to a greater reduction in resistance while improving the thermal conductivity. This type of concrete could improve the economic and environmental aspects by incorporating industrial wastes—mainly fly ash—thereby lowering the use of cement, which would lead to a reduction in CO2 emissions.
The recycling of construction and demolition waste (CDW) is currently of growing interest. Starting from such waste products it’s possible to produce recycled aggregates for construction purposes providing environmental and economic advantages. Life-cycle assessment (LCA) is a valuable tool to evaluate the environmental impact at end of life of CDW and improve the employment of recycled aggregates in concrete. In this research a life cycle evaluation of concrete mixtures made with CDW is performed to assess their environmental impacts considering various scenarios related to recycling sites with different conveying distances. The advantages of replacing natural aggregates with recycled ones are evaluated using a combination of LCA model and Life-Cycle Impact Assessment to estimate the environmental effects for all the considered scenarios. The results highlighted the highest environmental impact for the scenario with total landfill as well as an increasing impact for increasing distance from the demolition site.
Every year, in the world, the produced quantities of plastic amount to approximately 400 million tons. This implies a high level of plastic pollution and a growing decrease of available natural resources. Therefore, seems to be clear that there is a need to act in such a way as to reduce plastic pollution, safeguard natural resources and prevent the disposition of great quantities of waste in landfills or, even worse, the discharging into marine waters. This explains the need to implement processes of recovery and recycling of this plastic waste and their reuse in operable and practical products. Many studies analyzed the chances of employing plastic waste to produce cement and concrete, but the research about the use of polyolefins for the production of lightweight concretes is still limited. This study shows that the use of recycled polyolefins as substitutes of natural aggregates is a viable solution for the production of lightweight concretes by analyzing the influence of this kind of plastic on mechanical, physical and thermal performance, through experimental tests performed on four samples containing different amounts of plastic aggregates.
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