New eco-mechanical index for concrete structures

A new eco-mechanical index (EMI) has been introduced with the aim of quantifying the environmental impact of concrete structures. From a general point of view, this indicator represents the amount of carbon dioxide released to produce certain mixtures of pre-established strength and ductility. Both for normal strength and high strength concrete, with and without steel fibers, these mechanical properties are summarised by the work of fracture under tensile actions. If also structural durability has to be taken into account, the maximum crack width of reinforced concrete structures must be computed. This is possible by using a tension-stiffening model, here applied to reinforced concrete elements in tension. However, with or without the evaluation of crack width, the concrete with the best EMI releases the highest fracture energy. For this reason, the work of fracture represents also a durability parameter, and therefore it can be used to tailor cement-based composites with the highest strength, ductility, and durability, and the lowest environmental impact.