THE RE-USE OF SILICATIC STONE SAWING SLUDGE IN THE BUILDING SECTOR

The problem related to the reuse of sludge deriving from the cutting of ornamental stone is a relevant topic for many countries. Even if many studies are carried out on the recovery of sludge resulting from carbonatic cutting rocks the reuse of silicatic sawing sludge remains a challenge due to higher amount of metals than carbonatic stone sludge. Two kind of silicatic sawing sludge reuse in the building sector have been analysed on the basis of their physical-chemical characteristics. The recoveries were planned based on the sludge metals content. The first use, as CLSM (Control Low Strength Material), provided the use of sludge as filler with the goal to increase the capacity to dissipate thermal energy, due to the passage in the sub-road network of sub-services. The second reuse is for thermo-eco-mortar for plaster, as filler which allow a thermal insulation and at the same time a good mechanical resistance. The properties of mortar for plaster and of CLSM have been evaluated by means technological test on specimens made with different composition (mix design). The choice of the type of recovery was carried out on the basis of chemical and magnetic separations carried out during the sludge characterization steps. Moreover, chemical analysis and leaching tests were performed on the finished product to verify the amount of metals present in the product obtained. Economic evaluation has been carried out on the cost sludge disposal in comparison with its recovery as raw material for building construction, demonstrating an interesting approach not only on the environmental but also on the economic point of view.