Salinization of road base aggregates poses a critical challenge to the performance of coastal roads, as the intrusion of chlorine salts adversely affects the stability and durability of pavement structures. To investigate the cyclic behavior of salinized road base aggregates under controlled solution concentration, c, and crystallization degree, omega, a series of unsaturated cyclic tests were conducted with a large-scale triaxial apparatus. The results showed that variations in solution concentration had a negligible influence on the resilient modulus of road base aggregates, and no significant differences were observed in their shakedown behavior. However, the long-term deformational response of the aggregates was affected by the precipitation of crystalline salt. At low crystallization degrees, a significant increase in accumulated axial strain and a decrease in resilient modulus were observed with increasing omega. Once the crystallization degree exceeded a critical threshold (omega(c)), there was a reduction in accumulated strain and an increase in resilient modulus. The precipitation of crystalline salt also disrupted the shakedown behavior of road base aggregates. During the nascent stages of crystallization (omega < 0.33), the presence of fine crystalline powders and clusters in the saltwater mixture destabilized the soil skeleton, resulting in a transition from the plastic shakedown stage to the plastic creep stage. This poses potential risks to the long-term characteristics and durability of the road base courses.

To enhance the applicability of multiple solid waste road base materials in seasonally frozen soil areas and reduce the negative impact of red mud (RM) on the environment owing to its strong alkalinity, this paper utilizes untreated bayer method RM, fly ash (FA), and phosphogypsum (PG) as raw materials for preparing the road base materials. The mechanical properties, leaching characteristics, and Freeze-thaw (F-T) resistance of the materials from different solid waste systems were investigated through F-T cycle tests, unconfined compressive strength (UCS) tests, and leaching tests. The hydration, sodium solidification, and F-T deterioration mechanisms were revealed using an X-ray diffractometer and a scanning electron microscope. Results indicated that when the mix ratio of RM: FA: PG: cement was 64:28:2:6 (RFP2), the specimen exhibited the best F-T resistance. After 10 F-T cycles, the compressive strength retention rate (BDR) of the specimen was 91.43 %, and the Na+ leaching concentration was 390 mg/L, which still met the Chinese standard. The main hydration products of the material include C-S-H gel and ettringite crystals. These crystals and gels are intertwined and connected to form a dense mesh structure, which improves the material's F-T resistance and sodium solidification effect. The F-T cycle results in the expansion of cracks within the material, which leads to the destruction of the adhesion of the cementitious products, thus causing a deterioration of the strength of the specimen and the reduction of the sodium solidification effect.

This article discusses the utilization of industrial construction waste for resource recycling and disposal. It focuses on researching a new water-resistant, self-healing soil curing technology called road liquid, which is a fly ash-based soil curing agent. This technology is used for the curing of industrial construction waste disposal methods. For the first time, the soil curing agent is mixed into the construction waste along with cement stabilization. Different amounts of mixing are used as controls to evaluate the performance of the curing material after the construction waste is cured. The study focused on the material properties of cured construction waste, specifically examining strength, water resistance, and self-healing properties. The study showed that the curing agent road liquid enhanced the strength, water resistance, and self-healing properties of the cured construction waste at various cement dosages. The 7-day unconfined compressive strength of recycled aggregates with a 5% cement dosage, added with the curing agent road liquid, was higher than that of recycled aggregates with a 6% cement dosage without the curing agent road liquid. The experimental results show that using this type of granular solid waste as pavement base material is more practical for engineering purposes. The curing agent road liquid can enhance the curing effect of recycled aggregate, thereby reducing the need for cementitious materials and achieving cost savings for the project.

Scouring of roadbeds along river highways poses a significant threat to the safety of mountain roads. Relying on the Karakorum Highway (KKH) water damage disaster remediation project, using the erosion function apparatus and theoretical analysis, we studied the scour rate, starting shear stress, and the variation of theoretical model parameters in clay-coarse sand mixed soil samples with different clay contents. We also explored the scour characteristics and damage modes of mixed soils based on the soil skeleton theory. The following conclusions were drawn. As the clay content increases, the starting shear stress of the soil sample rises, scour resistance is strengthened, and the scour characteristics transition from non-cohesive to cohesive soil scour characteristics. The distribution of cohesive fine particles varies from filling the voids between coarse particles to bonding with them, and ultimately separating the coarse particles. The damage mode of the mixed soil samples under scouring water flow varies depending on the filling pattern of coarse particles and clays. The Wilson model exhibits a good fit with the experimental data and can be applied to predict large shear stresses, compensating for the limitations of the over-shear stress model.

The precipitation and intrusion of sodium chloride into pavement structures is inevitable in coastal regions, which can affect the mechanical properties of the road base courses. To investigate this problem, samples with sodium chloride solution were cured in a thermostatic chamber until they reached the specified states of sodium chloride precipitation within the pores. A critical crystallization degree (wc) was discovered by computerized tomography scan, corresponding to the start of the formation of porous salt crust cementing the soil particles. A series of unsaturated large-scale triaxial shear tests were then conducted under various states of salt crystallization. The results showed that in the early stages of crystallization (i.e., w wc, owing to the increasing adsorption and cementation effects of the salt crust, rapid growth was observed for the peak stress, internal friction angle, and apparent cohesion of the road base aggregates. Considering the influence of salt precipitation, a modified shear strength criterion that can predict the shear strength of the salinized road base aggregates was formulated.