# Unlocking the Potential of RFA and Stabilizers in High Moisture Geotechnical Applications
## 5 Conclusions  
This study discusses and analyzes the mechanical performance of recycled aggregate in conjunction with soft soil stabilizers after curing under specified water-immersion periods. By mixing varying proportions of recycled aggregate (20%, 40%, 60%) and soft  
Figure 13: R60C20-SEM micrographs (a,b). soil stabilizers (10%, 15%, 20%) with red clay at optimal moisture content, and conducting standard curing and water-immersion curing, the following conclusions were drawn from unconfined compressive strength tests (UCS), Field Emission Scanning Electron Microscopy (SEM), and particle size distribution tests (PSD):  
(a) The UCS test results show that when the recycled aggregate content is fixed, the unconfined compressive strength (\(q_{\text{u}}\)) increases with higher stabilizer content. Conversely, when the stabilizer content is fixed, \(q_{\text{u}}\) decreases as the recycled aggregate content increases. The highest \(q_{\text{u}}\) is achieved when both stabilizer and recycled aggregate contents are at 20%. Additionally, qu increases with curing time under different water-immersion periods (1 day, 5 days, 20 days, 40 days) and peaks at 40 days. These results indicate that combining recycled aggregates with stabilizers can maintain stable strength under water-immersion conditions, providing useful insights for engineering applications. (b) The triaxial test results reveal that the peak deviatoric stress increases with confining pressure. For the same confining pressure and recycled aggregate content, both peak deviatoric stress and shear strength parameters increase with higher stabilizer content. However, under constant confining pressure and stabilizer content, these values decrease as recycled aggregate content increases. (c) The mechanism for improving soft soil through the combination of recycled aggregates and soft soil stabilizers is primarily attributed to the interaction between the recycled aggregates and the stabilizer, which leads to the encapsulation and agglomeration of the aggregates by red clay. During the hydration reaction of the stabilizer, cementitious substances such as calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H) are formed. These products act as binding agents, filling the voids between the soil particles and recycled aggregates and significantly enhancing the internal cohesion of the mixture. The formation of these hydration products not only strengthens the bond between the particles but also improves the overall compactness of the soil structure. As a result, the sample exhibits an enhanced internal structure that contributes to the increase in unconfined compressive strength and overall mechanical stability. This process results in a more robust, dense, and stable mixture, offering an effective method for stabilizing soft soils. (d) PSD test results show that when recycled aggregate content is fixed, PSD curves shift to the right as stabilizer content increases, reaching a maximum at 20% stabilizer content. This indicates that the agglomeration effect caused by hydration reactions is strengthened, increasing the proportion of coarse particles and making the sample more compact internally. (e) The SEM analysis reveals significant changes in the microstructure of the stabilized soil, with detailed measurements and comparisons providing deeper insights into the structural improvements. The random distribution of recycled aggregates is encapsulated and agglomerated by red clay, and cementitious substances such as calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H) form during the stabilizer's hydration reaction. These products fill the voids between the soil particles, leading to a denser and more cohesive structure. Quantitative measurements of the particle size distribution, pore volume, and the density of cementitious products further emphasize the structural enhancement.