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Towards the sustainable development goals in the built environment, the use of waste and recycled sources has been attaining great interest among researchers and policy-makers, especially in concrete as the most used construction material. Excess use of natural aggregates, as one of the main components of concrete, causes the depletion of natural resources and the associated environmental problems, thus, the use of artificial and recycled aggregates is of great importance. In this regard, the production of lightweight artificial aggregates from industrial and hazardous wastes may be a promising solution that not only mitigates the depletion of natural resources but also stabilize those kinds of wastes. This study aimed to investigate the production of concrete with recycled aggregates from industrial wastes, mainly municipal solid waste incineration fly ash (MSWI-FA). To this end, different kinds of mix designs to manufacture the aggregates were developed based on MSWI-FA, ground granulated blast furnace slag (GGBFS), marble sludge (MS), and cement. The concrete samples containing different artificial aggregates, as well as recycled polyethylene terephthalate (PET) in the sand form, were produced and the properties, including compressive strength and thermal insulation, were evaluated. The obtained results of the lightweight concrete demonstrated enhanced thermal property (up to 30%), but at least 30% lower resistance with respect to the normal concrete produced from the natural aggregate.

In recent years, in the field of waste management, waste-to-energy plants have been attained great attention as a valid method for mitigating landfill disposal in addition to valorizing waste from the energy point of view. Moreover, there are several technological proposals aimed at valorizing and reusing the residues produced by incinerators. Nonetheless, pre-treatment and treatment techniques, including washing and the solidification/stabilization process, may be necessary for the recovery and recycling of this type of by-product. In this regard, the objective of this research is the production of lightweight artificial aggregates with acceptable quality, capable of guaranteeing specific requirements and technical performance, through the recycling of fly ash derived from municipal solid waste incineration (MSWI). The properties of the three types of aggregates, produced through the cold-bonding pelletization, were evaluated through the mechanical and leaching tests.

Utilizing recycled fibers as reinforcement in cement-based matrices is an effective means of promoting waste recycling and adopting a circular economy approach in the construction industry. Within this framework, the recycling and potential reutilization of textile residues can improve the pre- and post-cracking performance of cement-based matrices intended for building components with up to intermediate structural responsibilities (i.e., panels and cladding elements for buildings). This research is focused on the mechanical and durability -through forced aging of dry-wet and freeze-thaw cycles- experimental characterization of laminated fabric-reinforced cementitious matrices (FRCMs) containing 4 and 6 nonwoven fabric layers obtained from end-of-life fire-protecting t-shirts. For this purpose, both direct and flexural tensile tests were conducted to characterize the mechanical performance of the composite. The tests on the 6-fabric layers produced panels with Portland Cement (PC) matrix, after 28-day of curing, led to average values of the maximum tensile strength of 3.7 MPa with associated toughness index superior to 25 kJ/m2, and mean modulus of rupture of 11.6 MPa with a fracture energy index of 4.3 kJ/m2. After dry-wet accelerated aging, the post-cracking performance of the developed composites decreased (on average, 40% in toughness and 11% in strength) due to fiber embrittlement. To better understand the performance of aged composites, shredded fibers recovered from protective clothing (mainly consisting of meta-aramid fibers) were immersed in the binary matrix. Accordingly, the mechanical properties of the fibers after 5 and 10 cycles of dry-wet aging were studied. Based on the results, replacing partially PC by silica fume (between 30% and 50%) was seen as a sustainable alternative to improve the performance of the aged fibers by more than 10%.

•Short textile waste fibers (TWF) as reinforcement of cementitious materials are investigated.•Design-oriented mechanical and durability properties were characterized by testing.•8% of TWF proved to be the optimum dosage for building components with limited structural responsibility.•Accelerated aging on TWF composites led to lower detrimental effects in comparison with those on control samples.