The drying shrinking characteristics of red mud-based cementitious material stabilized Yellow River sand as pavement base

To address the significant drying shrinkage issues associated with cement-stabilized Yellow River sand, a novel red mud-based cementitious material (RCM) was developed utilizing some industrial solid wastes, such as red mud and fly ash, as replacement for cement in Yellow River sand stabilization. Comprehensive evaluations including mechanical performance testing, drying shrinkage testing, and microstructural characterization were conducted. Specifically, at a dosage of 15 %, the unconfined compressive strength (UCS) of RCM-stabilized Yellow River sand met the Chinese standard requirement for secondary pavement base. Drying shrinkage tests revealed that under 40 % and 60 % relative humidity conditions, the drying shrinkage strain of RCM-stabilized Yellow River sand specimens decreased by 24.11 % and 23.99 % compared to conventional cement-stabilized Yellow River sand, respectively. Microstructural analysis demonstrated that the reduction in drying shrinkage primarily resulted from two factors: on the one hand, an increased abundance of ettringite was observed in its hydration product was confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM) results, which could compensate the drying shrinkage of the stabilized matrix; on the other hand, the decreased proportion of mesopores (2–50 nm) in the pore size distribution and the reduced surface tension of the pore solution within the stabilized matrix. This study systematically elucidates the drying shrinkage mitigation mechanism of RCM-stabilized Yellow River sand, providing a reliable solution for applications of industrial by-products in road engineering. • Novel red mud-based cementitious material (RCM) replaced cement in Yellow River sand stabilization. • 15 % dosage of RCM achieved required unconfined compressive strength for secondary pavement base. • Drying shrinkage reduced by 24 % through ettringite formation and pore structure optimization. • Mesopore proportion reduction and lower pore solution tension mitigated shrinkage in stabilized matrix.