This study investigates the strength and microstructural evolution of SRX-stabilized aeolian sand–gravel mixtures for flexible base applications in desert roads. CBR, UPS (uniaxial penetration strength), and compressive resilient modulus tests were conducted under varying SRX dosages (0.4–1.0%) and aeolian sand contents (30–50%). The results show that increasing the SRX dosage significantly improves all three indices, with the 0.5% SRX and 30% aeolian sand mixture yielding the CBR (385.89%) and UPS (0.938 MPa) and achieving a compressive resilient modulus that meets the requirements for graded aggregate base layers. XRD FTIR and SEM–EDS analyses reveal that the SRX enhances material structure primarily through physical mechanisms, forming dense films and bonding networks without inducing significant chemical reactions. Extended curing improves structural integrity, while excessive aeolian sand reduces compactness. SRX-stabilized aeolian sand gravel is a viable base and subbase material for desert highways.