## 1 Introduction  
The construction of road infrastructures often entails the installment of utility lines which in most cases, for protection purposes, are buried in the pavement subgrade. High-voltage transmission cables are among these utility lines, and their ampacity depends upon the temperature they reach during power transmission. In fact, these cables are designed to transfer power at maximum current carrying capacity [1], thereby generating heat as a function of the thermal properties of the surrounding subgrade material. If such a material does not dissipate heat effectively, temperature of the cables may exceed the optimum operation value (65-70 \({}^{\circ}\)C) and may consequently compromise their service life [2]. The resulting scenario can be catastrophic in the sense that repair operation may require, in addition to cable substitution, demolition and reconstruction of the entire pavement. As a result of the heat-related issues outlined above, in the presence of high-voltage cables, in the formation of subgrade fills, use can be made of specifically designed composite materials known as \"thermal backfills\". These materials exhibit a sufficiently high thermal conductivity that enhances heat dissipation from buried cables and consequently reduces their core temperature [1; 2; 3; 4]. Thermal backfills are also designed to maintain their properties as stable in time, thereby limiting the effects of the progressive creation of dry zones near the cables, as in the case of typical subgrade soils, which can lead to a significant decrease of conductivity and to the reduction of cable rating [4; 5; 6; 7]. In some cases, depending upon design requirements and construction constraints, thermal backfills can be conceived and produced in the form of Fluidized Thermal Backfills (FTBs). Such a category of materials includes self-compacting and self-leveling flowable mixes, which are ideal for applications in tight and challenging geometrical configurations where laying and compaction operations may be especially complex. FTBs are constituted by hydraulic binder (i.e., cement), aggregates, water, and chemical admixtures; however, several recycled components can be included in their composition, with a corresponding reduction of production costs and environmental impact [4; 8; 9; 10; 11; 12; 13; 14; 15; 16]. Different factors affect the thermal properties of cementitious backfilling materials. [PERSON] et al. [17] found that the volume of aggregate fractions and moisture content affected the conductivity of backfilling mixtures, although non-negligible effects were also attributed to chemical admixture type and cement dosage. [PERSON] et al. [18] and [PERSON] [19] observed that thermal conductivity was affected by cement dosage and type, water-to-cement (W/C) ratio, mix density, and mineralogical structure of aggregates. [PERSON] et al. [11] pointed out that composition parameters such as W/C ratio, cement type, and dosage had the main effects on thermal properties, while a lower influence was attributed to the mineralogical nature of aggregates. Nevertheless, they observed that the conductivity of backfilling mixtures was improved in the presence of increasing values of quartz content. Finally, while investigating the thermal properties of FTB mixtures, [PERSON] et al. [14] reported the negligible effects due to curing time, whereas they underlined the fundamental role played by cement content, W/C ratio, and aggregate type. The study described in this paper focused on the characterization of FTBs that were specifically designed to achieve satisfactory thermal and mechanical properties. However, as described in detail in the following, the main goal of the investigation was to assess the feasibility of using sawing sludge in their production. Sawing sludge is generated by cutting operations that are performed during the processing of ornamental stones.