Product-specific Life Cycle Assessment of ready mix concrete: Comparison between a recycled and an ordinary concrete

Recycled concrete is one of the most efficient answers to the shortage of natural aggregate in highly populated and protected regions, such as Switzerland. Although the technology has evolved and today a number of certified recycled concretes are available in the ready mix concrete market, there are still many barriers to its use for structural purposes. These are caused by early tests that, analyzing non-optimized or non-commercial products, reached the conclusion that the performances of recycled concrete would not match the ones of ordinary concrete. Furthermore, early studies on the environmental impact of recycled concrete seemed to confirm an identical environmental impact for recycled and ordinary concrete (Viviani 2011; Viviani 2014). In this paper, is presented a thorough Life Cycle Assessment (LCA) for a commercialized recycled concrete and a commercialized ordinary concrete of the same strength class, both certified, both deeply characterized, showing virtually identical physical and rheological properties and sold at the same price (recycled concrete price being slightly lower than the ordinary). This LCA study shows that recycled concrete is only slightly better than ordinary concrete in terms of greenhouse gases emissions. This difference is yet not enough significant (1%) as well as for the cumulative energy demand (4%). In opposite, it performs better with around 12% less environmental impacts according to the Swiss Ecological Scarcity 2006 Method. So, current actions taken to promote their use are fully in the direction of a more sustainable construction industry if the transportation distance to the construction site is minimized and below e.g., 25km as recommended in the Swiss Minergie ECO label.