Assessing the potential of functionally graded concrete using fibre reinforced and recycled aggregate concrete

Despite ordinary Portland cement concrete presenting low performance in tension and a negative impact on the natural environment, it is the most used construction material. Researchers have noted that the usage of fibres as reinforcement and recycled aggregates, instead of natural ones, may minimize these issues. The concept of functionally graded material for new composite materials is proposed to address these problems. In this paper, five different concrete mixes were produced to analyse the potential of using functionally graded concretes (FGC) for sustainable structures. Their mechanical performance, a sustainable quality control method for these materials and their costs and embodied CO₂ were analyzed. The results show that FGC, even though showing a post-cracking flexural performance lower than conventional FRC, possesses high potential in terms of structural design based on Model Code 2010 specifications. The equations provided to use the Barcelona test to control the material, which is more environmentally friendly than the standardized beam test, may facilitate the introduction of FGC in the construction market. Finally, considering costs and embodied CO₂, FGC presents a good prospect to be used as structural material for future sustainable concrete elements.