Sustainable reuse of marble sludge in tyre mixtures

The problem of the large amounts of waste products deriving from ornamental stone industrial activities affects not only the environmental impact but also the resources maintenance and the problem of waste management. This paper presents the essential features of an environmentally attractive reuse of what is currently considered a marble waste: marble sludge, recovered from marble sawing and slurry processing. A research is currently carried out in order to join this by-product with possible industrial applications. Simplified rubber formulations, filled with dewatered marble sludge and cross-linked by vulcanization, have been investigated with the objective of making a comparison with tyre compound obtained by using commercial calcium carbonate filler. From this, rigorous analyses have been carried out. The structural effect of calcium carbonate particles on tyre mixtures tensile strength, hardness, rheometric and morphological properties was inspected. The investigation focused on the materials collected by Orosei marble producing area (NE Sardinia-Italy) and it was carried out in cooperation with the Research & Development Laboratory by Marangoni Spa (Italy). The data emerging from the tests demonstrate how environmental burdens in conjunction with stone production could be reduced to much lower levels, by identifying the way to use marble sludge as filler in high added value products.