## 2 Literature Review
Moreover, the use of lignosulfonates as dust suppressants provides some environmental benefits as they are typically non-toxic, biodegradable, and non-corrosive, as well as more efficient than other chemical alternatives [42]. Lignosulfonates can be used as soil stabilizers and dust suppressants in different soil conditions. In terms of cost benefits, their implementation is more effective for soils characterised by a plasticity index greater than 8 and a percentage of fines in the range of 8-30%; moreover, some restrictions are defined depending on factors such as traffic, climate, and weather conditions [41]. A long-term disadvantage of the use of lignosulfonates in the field of roadway surfacing is related to their poor water resistance; therefore, their use is not recommended in wet conditions and high precipitation areas [41]. Some studies investigated the decrease in sulphur content as a solution for the reduction in the soluble property of lignosulfonates [15; 42]. A study by [PERSON] [43] aimed at finding a cost-effective solution for road stabilization and maintenance of unpaved roads in order to minimize dust generation, erosion phenomena, and surface wear. An experimental analysis was carried out to investigate the performance of various additives including lignin sulfonate. The results showed that lignin sulfonate contributed to increasing the compacted dry density; however, in specific weather conditions (wet environments, rainwater, melting snow), the additive tended to leach out of the material. For this reason, the author suggested taking into account the climate together with traffic and road surface geometry in selecting and applying the additive. Another research in this field [44] suggests that lignocellulosic and other wood products and by-products can be a suitable alternative to gravel as stabilizing materials of unpaved low-volume roads. A lignin-based emulsion was used to improve the stability of a low-volume forest road in Alabama [45]. Field CBR values showed an increase in surface and subgrade strength characteristics. A blend of emulsified bitumen and lignocellulosic was used for a series of road construction projects for a total length of 115 km. The results reported that the stabilizer method improved the load-bearing capacity of the roads and provided an increased rate of compaction [36; 46]. Furthermore, [PERSON] et al. [47] stated that lignocellulosic are an effective treatment in the mitigation/elimination of the possibility of soil erosion for silty sand. Several studies investigated the potential of lignin as an asphalt substitute in order to develop an environmentally friendly alternative to asphalt binders [48]. [PERSON] et al. [49], in their research on lignin-modified asphalts, found that a higher lignin content increased the viscosity and decreased the ductility of the binders. Similar results were found by [PERSON] and [PERSON] [50] in their analysis of the rheological characteristics of two types of asphalt binder modified with different lignin contents. Furthermore, [PERSON] and [PERSON] found that the presence of lignin improves the performance of the asphalt binder at high temperatures in terms of rutting resistance.