Performance-Related Assessment of the Potential Use of Sawing Sludge in Cementitious Fluidized Thermal Backfills

• Main Authors: Lorena Zichella, Eldho Choorackal, Michela Airoldi, Pier Paolo Riviera, Rossana Bellopede, Ezio Santagata
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Applied Sciences
• Subjects: circular economy; sawing sludge; Fluidized Thermal Backfill (FTB); buried electrical cables; thermal conductivity; resilient modulus
• Online Access: https://www.mdpi.com/2076-3417/10/22/8243

The management of sawing sludge originated from cutting operations of ornamental stones represents a challenging task as a consequence of its peculiar composition that includes non-negligible amounts of heavy metals resulting from the wear and tear of cutting tools. The aim of the research work presented in this paper was to investigate the feasibility of using these by-products as supplementary constituents of cementitious mixtures employed for the formation of Fluidized Thermal Backfills (FTB). These mixtures are designed and produced for filling operations in pavement subgrades in which high-voltage electrical transmission cables are buried for protection purposes. Two different types of sawing sludge were thoroughly analyzed from a physical and chemical point of view and thereafter employed for the laboratory production of four FTB mixtures. Then, these were subjected to thermal, mechanical, and environmental tests in order to verify their suitability for their intended use. All investigated FTB mixtures exhibited a satisfactory and stable thermal conductivity, and they also displayed enhanced stiffness properties in comparison to standard subgrade and sub-base materials. Controversial results were obtained with respect to environmental properties resulting from leaching tests, thus suggesting that further investigations are needed before any full-scale application can take place.