**7. Effect of Granite Dust and Stabilizer(s) on Geotechnical Behavior**

#### *Importance of the Stabilizer*

Granite dust is a non-plastic cohesion less material with a specific gravity greater than that of soil. Adding granite dust to cohesive soil filled the voids in cohesive soil, which increases the density and the shear strength. However, in some cases, granite dust alone will not be sufficient to fulfil the requirements that may cause sudden drawdown or a slip as seen from Figure 7. The soil-granite mix requires a binding agent to bring an efficient product to work in the field that can withhold the heterogeneous mass.

**Figure 7.** Significance of the secondary stabilizer.

When clay soil was stabilized with granite dust, the plastic nature of the soil decreased with the increase in the granite dust dosage, leading to failure. The presence of a binding material prevented failure and increased the cohesion which enhanced the engineering properties. Black cotton soil when amended with lime and granite dust exhibited better performance compared to untreated scenario [55]. The ettringite formation increased the strength of the soil–granite dust mix (Figure 8). Granite dust, along with calcium carbide residue (CCR) in equal amounts, showed a good influence on problematic silty clay in terms of the CBR (Figure 9) [26]. The presence of the CCR in silty clay led to pozzolanic reactions and increased the chemical bonding between particles.

**Figure 8.** SEM images (**a**) of black cotton soil and (**b**) black cotton soil mixed with 9% lime and plugged with 25% granite dust (Sourced from [55]).

**Figure 9.** Response for the soaked CBR test after 14 days of curing. Case I-Soil + 5% granite dust + 5% CCR. Case II-Soil + 10% granite dust + 10% CCR (Modified after [26]).

Some works on foundation soil improvement were performed using granite dust and cement, where the soil was improved with the incremental addition of granite dust with 4% cement addition. Granite dust with 10% cement addition improved the shear strength and the hydraulic properties of lithomargic clay [46]. The presence of cement led to ettringite formation, which helps in developing additional strength and cohesion. The presence of cement also helped in decreasing the pore volume. Dutta and Sarda [54] used a waste plastic strip with granite dust/flyash to improve the kaolinite clay properties. The CBR variation in the mix was attributed to the strip intrusion and the strip length in granite dust. The high-plastic silt was added with cement and granite to improve the CBR [42]. Quarry wastes in the form of granite powder and muck could be used as a supplemental subgrade material when added with lime [56]. The effects of quick lime on compacted granite dust were also studied, and the bearing capacity was found to improve with quick

lime addition. Table 8 provides the summary of various earlier works which necessitated the inclusion of binder to granite dust.


**Table 8.** A Summary of works to improve the properties of soil mixed with granite dust and a binder.
