At present, achieving good storability and water damage resistance remains challenging for cold-patching asphalt mixtures (CAMs). To address this issue, this study selects styrene–ethylene–butadiene–styrene copolymer (SEBS) and diesel as a modifier and diluent, respectively, to improve the water stability and storability of CAMs. The diesel oil content is determined through the Brookfield rotational viscosity test, and the modifier content is obtained through the Marshall stability test. With the empirical formula method, paper trail test, and modified Marshall test, mixed designs of CAMs modified with and without SEBS are established to determine the best cold-patching asphalt content. On this basis, the modification effect of SEBS is verified by comparing the test results of the modified and unmodified CAMs, and the water stability and Marshall stability tests are conducted before and after CAM storage, respectively. Results show that the optimum contents of SEBS and diesel oil are 7.5% and 40% of the base asphalt weight, respectively, and the best modified asphalt content is 4.6% of the mineral material weight in CAM. The Marshall residual stability and freeze–thaw splitting strength ratio of the 7.5% SEBS-modified CAM are increased by 20.1% and 15.7%, respectively, relative to the unmodified CAM, and the storage performance requirement of at least two months can be guaranteed.

To improve the water damage resistance performance of a tuff asphalt mixture, a tuff mixture with cement and a liquid anti-stripping agent was used as the research object, and limestone and tuff mixtures without additives were selected as contrast samples. Through an improved boiling test and a water stability test before and after aging, the modification effect of the tuff mixture with additives of different types and contents on water damage resistance was evaluated to obtain the appropriate type and content of additives. On this basis, the other road performance measures of the selected mixture were further evaluated by immersion rutting and beam bending tests to verify the modification effect of the additive on the tuff mixture. Results showed that adding the appropriate cement content to the tuff mixture provided excellent resistance to the water damage effect. An optimal content of 2% cement additive in the mixture was obtained, and its high-temperature anti-rutting and low-temperature bending performance were also verified. Adhesion between tuff aggregates and asphalt polymer under water conditions was significantly improved and close to that of limestone aggregates. The modification effect of water stability after mixture aging was better than that of the anti-stripping agent. The residual stability and freeze–thaw splitting strength ratio of 2% cement content mixture were increased by about 21.5% and 16.7%, respectively, compared with those of the tuff mixture control.

On the basis of a modified three-dimensional (3D) random distribution fiber model, this study further investigates the flexural–tensile rheological behavior and its influence factors of fiber-reinforced asphalt mortar. First, the viscoelastic creep at a temperature of 15 °C for pure asphalt mortar as the control sample are obtained by the beam bending creep test to fit the Burgers constitutive parameters. Second, a 3D numerical model consisting of a homogeneous asphalt mortar matrix with viscoelastic parameters and short and straight fibers with elastic characteristics is built in a cuboid space on the basis of a fiber algorithm to simulate the flexural–tensile rheological behavior using ABAQUS software, and the rheological behavior of the 3D model is consistent with those of the test result. Finally, 3D numerical simulations are conducted to further analyze the effect of fiber factors (e.g., contents, aspect ratios, modulus, and fiber types) on the rheological behavior. Results show that the effect of basalt fiber (BF) compared with steel wool fiber are more significant, and increasing fiber contents and aspect ratios have a positive reinforcement effect on the rheological behavior, where BF content for 0.1%, 0.2%, and 0.3% at 3600 s compared with the control reduced by 37.5%, 53%, and 61.7%, and BF aspect ratios for 30, 40, and 50 compared with that for 20 increased by 4.3%, 16.1%, and 32.9%, respectively, but the change in fiber modulus has a minimal impact.

This study mainly investigates the prediction models of shear parameters and dynamic creep instability for asphalt mixture under different high temperatures to reveal the instability mechanism of the rutting for asphalt pavement. Cohesive force c and internal friction angle φ in the shear strength parameters for asphalt mixture were obtained by the triaxial compressive strength test. Then, through analyzing the influence of different temperatures on parameters c and φ, the prediction models of shear strength parameters related to temperature were developed. Meanwhile, the corresponding forecast model related to confining pressure and shear strength parameters was obtained by simplifying the calculation method of shear stress level on the failure surface under cyclic loading. Thus, the relationship of shear stress level with temperature was established. Furthermore, the cyclic time F_N of dynamic creep instability at 60 °C was obtained by the triaxial dynamic creep test, and the effects of confining pressure and shear stress level were considered. Results showed that F_N decreases exponentially with the increase in stress levels under the same confining pressure and increases with the increase in confining pressure. The ratio between shear stress level and corresponding shear strength under the same confining pressure was introduced; thus, the relationship curve of F_N with shear stress level can eliminate the effect of different confining pressures. The instability prediction model of F_N for asphalt mixture was established using exponential model fitting analysis, and the rationality of the model was verified. Finally, the change rule of the parameters in the instability prediction model was investigated by further changing the temperature, and the instability forecast model in the range of high temperature for the same gradation mixture was established by the interpolation calculation.

At present, tuff aggregates as asphalt pavement mixtures have insufficient water damage resistance; hence, modifying and evaluating the related properties of tuff asphalt mixtures are necessary. In this study, cement and a liquid antistripping agent were selected as admixtures, and tuff and limestone mixtures without admixtures were selected as control. The surface energy for the SBS-modified asphalt polymers and aggregates in the mixtures was evaluated by using surface energy theory. The adhesion work and the spalling work of the polymer–aggregate interface was calculated, and a factor k was proposed to predict the water damage resistance of the tuff mixture with admixtures. The prediction values were compared with those of the macroscopic water stability test for the mixture. The results of this research showed that the factor k after adding admixtures was improved, and the increase range was from 7.14% to 47.62%. The admixture scheme with the best improvement was that with 2% cement content, in which the k value increased by 21.57% and 47.62% compared with that of the limestone and tuff mixtures without admixtures, respectively. The tested water stability indexes and the predicted factor k under different admixture schemes exhibited a good positive correlation, and the correlation equations were obtained by linear fitting. Thus, it was feasible to use the factor k characterizing the water damage resistance of tuff mixtures using surface energy theory.

The aim of this study is to further investigate the effect of different basalt fiber (BF) factors on the viscoelastic equivalent creep behavior of fiber‐reinforced asphalt mixture (FRAM) under indirect tensile (IDT) condition. A two‐dimension mesostructural model composed of different components including fiber mortar polymer and coarse particle aggregate is constructed via the section image processing for the IDT FRAM specimen, where BF is considered as random distribution in the mortar polymer. Furthermore, the stress distribution and equivalent creep of the IDT mesostructural model in simulation software are analyzed to discuss the influence of components on the creep behavior of FRAM. Moreover, the laboratory creep test of IDT specimens under 0% and 0.3% BF contents for FRAM is carried out to validate the simulated values. Research results indicate that the simulated creep deformation of the IDT mesostructural model is in agreement with that of the experiment. Finally, creep simulations are further conducted to discuss the effect of BF (e.g., fiber content, length‐diameter ratio, and fiber modulus) and aggregate on the creep characteristic of FRAM. The increase of fiber content and length‐diameter ratio has a significant reinforcing effect on the equivalent mechanical behavior, but the change in the modulus of fiber and aggregate has slight effects.