## 6 Conclusions and Recommendations for Future Work  
The current paper discussed the use of CACW and clarified how it affects silty sand soils with various mineralogies in terms of their engineering characteristics. The viability of soils supplemented with CACW in the presence of an additional stabilizer (2% cement) has been evaluated. Discussion is held over the effectiveness of CACW as a backfill and paving material. Each soil engineering property improvement caused by the addition of CACW has a mechanism that is detailed. The principal results of this paper are as follows:  
1. The improvement in the corresponding maximum dry density and shear strength causes an increase in soaked CBR values.
2. Adding a small amount of additive (10%) to CACW improves the engineering properties of silty sand soils. This addition causes a net reduction in pore volume, aids in the quick development of dense mixes, and significantly increases compressive strength.  
3. The test findings showed that the optimum dosage is 10% CACW with 2% cement, raising the undrained shear strength of silty sand soil by 323%, CBR by 286%, and P-wave by 180%.
4. The durability tests reveal that soil containing 10% CACW and 2% cement satisfies the specifications and stays within the 14% weight loss limit imposed by the Portland Cement Association (PCA).
5. For subgrade and subbase layers, only silty sand soil stabilized with 10% CACW and 2% cement is suitable, in accordance with the durability findings and strength criteria. The other, on the other hand, is applicable to other field activities, such as enhancing the carrying capacity of sandy marl soil on pavements and low to moderately high-rise buildings.
6. The microscopic investigation results confirmed the outcomes obtained by macro tests.
7. This study clarifies the long-term effects of CACW on improving the engineering properties of silty sand soil in the Najran Region of the Kingdom of Saudi Arabia and other comparable soils globally. The general implications of this research and its prospective benefits are those for improving the geotechnical qualities of silty sand soils for road pavement applications and enhancing the bearing capacity under foundations and embankments.
8. The authors recommend addressing the effects of adding CACW to other kinds of soil, such as clayey soils, which are distributed over large areas of Najran city as well as many other places overall in the Kingdom of Saudi Arabia.  
Conceptualization, G.M.S.A., A.A.E.A., M.A.S. and A.E.R.; methodology, G.M.S.A., A.A.E.A., M.A.S. and A.E.R.; software, G.M.S.A., A.A.E.A., M.A.S. and A.E.R.; writing--original draft preparation, G.M.S.A., A.E.A., M.A.S. and A.E.R.; writing--review and editing, G.M.S.A., A.A.E.A., M.A.S. and A.E.R.; visualization, G.M.S.A., A.A.E.A., M.A.S. and A.E.R.; supervision, G.M.S.A., A.A.E.A., M.A.S. and A.E.R.; funding acquisition, G.M.S.A. and A.E.R. All authors have read and agreed to the published version of the manuscript.  
The authors are thankful to the Deanship of Scientific Research at Najran University for funding this work under the General Research Funding program grant code (NU/DRP/SERC/12/47). [PERSON] is thankful to the Priority Research Area Anthropocene under the program \"Excellence Initiative--Research University\" at the Jagiellonian University in Krakow.  
Data Availability Statement: Data supporting the findings of this study are available from the corresponding author upon reasonable request.  
The authors are thankful to the Deanship of Scientific Research at Najran University for funding this work under the General Research Funding program grant code (NU/DRP/SERC/12/47). [PERSON] is thankful to the Priority Research Area Anthropocene under the program \"Excellence Initiative--Research University\" at the Jagiellonian University in Krakow. Authors would like also to thank Rn Harkil for Granite rock for their logistic support during the research.  
The authors hereby declare that they have no conflict of interest.