Reuse of river sediments in pervious concrete: Towards an adaptation of concrete to the circular economy and climate change challenges

The construction industry is one of the main sectors responsible for today's climate change as well as the extraction of large volumes of raw materials for concrete manufacturing. At the same time, significant volumes of sediments are being dredged each year (in France, nearly 60 M m3), and given their waste status these materials are barely or not at all being reused. This industry is the primary target chosen by sediment managers to ensure a viable and sustainable reuse stream. More specifically, pervious concrete is considered as a green infrastructure solution for urban areas. In this work, sediments dredged from the Seine Basin in Paris (France) were used to produce a cleaner pervious concrete. Two sets of pervious concretes were prepared, the first based on sandy sediments by fully substituting the conventional sand, while the second set of concretes was based on fine sediments by partially substituting the cement. Slump, fresh density, hydration, porosity, permeability, compressive strength, tensile splitting strength and thermal conductivity were all evaluated through testing. Results show that the incorporation of sediments delayed, albeit marginally, the cement hydration (by less than 3 h) due to the presence of organic matter. The properties of pervious concrete are affected by the grain size of the incorporated sediment. The finer the sediment, the more compact the concrete structure, hence generating less porosity in the mixture, lower permeability and higher compressive strength. The thermal conductivity and volumetric heat of these pervious sediment-based concretes were also comparable to measures of the control concrete yet lower than those of ordinary concrete.