# Experimental Study on Scour Resistance Performance Enhancement of Chongqing Red Clay
## 5 Conclusions  
This study conducted flowability tests, anti-dispersion tests, scour resistance tests, and microstructural analyses on Chongqing red clay, investigating the effects of curing agent dosage, cement content, and water-to-solid ratio on these properties. The main conclusions are as follows:  
(1) Increasing curing agent dosage significantly reduces the flowability and suspended solids content of solidified soil while showing negligible impact on critical shear stress. When the curing agent dosage increases from 0% to 0.4%, the suspended solids content decreases by 93.3% (from 750 mg/L to 50 mg/L), the initial flowability decreases by 42.3% (from 390 mm to 225 mm), the 1-h flowability decreases by 42.3% (from 260 mm to 150 mm), and the 2-h flowability decreases by 31.4% (from 153 mm to 105 mm);  
(2) Increasing cement content markedly enhances the critical shear stress of solidified soil, slightly improves short-term flowability with reverse effects over time, and minimally affects anti-dispersion performance. When cement content increases from 6% to 14%, the critical shear stress at 2 h, 4 h, and 6 h increases by 100%, 114.8%, and 81.9%, respectively;  
(3) Reduced water-to-solid ratio mitigates the weakening effect of free water on interparticle cohesion in solidified soil, decreasing both suspended solids content and flowability while increasing critical shear stress. When the water-to-solid ratio decreased from 0.6 to 0.4, suspended solids content reduced by 91.4%, with 0-h, 1-h, and 2-h flowability decreasing by 49.7%, 51.7%, and 41.2%, respectively, while 2-h, 4-h, and 6-h critical shear stress increased by 307.6%, 163.2%, and 119.5%;  
(4) The optimal mix proportion (0.3% curing agent, 10% cement, 0.5 water-to-solid ratio) meets both specification and construction requirements, serving as the optimal formulation for solidified soil's scour resistance. SEM analysis demonstrates that red clay particles exhibit loose arrangement with abundant pores and weak cohesion, resulting in poor scour resistance. The generated C-S-H gels and ettrin9 ite (AFt) in solidified soil fill interparticle voids, enhancing the integrity of red clay and interparticle cohesion, thereby improving scour resistance to meet performance criteria. The relationship between suspended solids content and flowability can be accurately described by a quadratic polynomial with a fitting coefficient R\({}^{2}\) of 0.977.  
Figure 17: SEM images of red clay and solidified soil. (**a**) Red clay, 500\(\times\); (**b**) Red clay, 3000\(\times\); (**c**) 0.3-10-0.50, 3d, 3000\(\times\); (**d**) 0.3-10-0.50, 3d, 8000\(\times\); (**e**) 0.3-10-0.50, 28d, 3000\(\times\); (**f**) 0.3-10-0.50, 28d, 8000\(\times\). The end of the arrow represents the name of the substance, and the front of the arrow represents the specific substance in the figure. The yellow arrow represents ‘Aft’.  
**Author Contributions:** Methodology, Q.W.; data curation, D.W.; writing--original draft, D.W.; writing--review and editing, D.W.; supervision, Q.W., Y.Q. and S.W. All authors have read and agreed to the published version of this manuscript.  
**Funding:** This study received no external funding.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Conflicts of Interest:** The authors declare no conflicts of interest.