Elaboration of a Self-Compacting mortar based on concrete demolition waste incorporating blast furnace slag

The high consumption of natural sand in the manufacture of mortar and concrete has inevitably led to serious ecological impacts. On the other hand, the steel industry is always accompanied by the production of unused by-products such as granulated blast furnace slag. This research aims to use a fine fraction of construction and demolition (C&D) waste as a substitute for natural sand and, ground granulated blast furnace slag (GGBFS) as a substitute for cement for the manufacture of self-compacting mortars. 15 mortars are formulated where 0, 25, 50, 75 and 100% natural sand (NS) are replaced by recycled concrete sand (RCS) and 0, 20 and 40% ordinary cement are replaced by GGBFS. The obtained results show that it is possible to manufacture self-compacting mortars with RCS, with an optimum of 50%. The use of this type of sand affects negatively the porosity and capillarity water absorption of mortars; this can be compensated by the use of GGBFS as a cement substitute. A 20% slag sub-stitution rate can also improve the long-term compressive strength.