Context:

Concrete production is characterized by a significant demand of energy and raw materials, and by emitting large amounts of greenhouse gases (GHG). Moreover, the processes of construction, maintenance, and demolition of buildings generate huge quantities of waste that require costly and environmentally sensitive disposal procedures. Therefore, several solutions are being investigated to reduce the environmental impact of the processes associated with the life cycle of concrete.

Methodology:

Through experimental tests, the physical and mechanical properties of three sustainable concrete mixtures were studied: concrete with recycled aggregates, concrete with partial replacement of Portland cement by fly ash, and cementitious composites reinforced with recycled fibers.

Results:

The use of coarse recycled aggregates degraded the mechanical characteristics of the concrete due to their greater porosity and water absorption capacity. However, the mixture made out of recycled aggregates and fly ash showed a synergistic effect, mitigating the adverse consequences mentioned. The post-cracking response of concrete reinforced with recycled steel fibers was characterized by a lower tenacity and ductility compared to composites with industrial fibers. Specifically, mixtures with recycled fibers showed a more pronounced softening stage. This revealed a lower efficiency of recycled fibers compared to industrial fibers.

Conclusions:

The experimental results showed that the incorporation of recycled materials led to a deterioration in the physical and mechanical behavior of the analyzed composites. However, the resulting properties exceeded the recommended minimum values required for their application as structural materials.