In this study, cellulose and basalt fiber were introduced simultaneously to stone mastic asphalt (SMA) to investigate the effects of hybrid modification on performance improvement of asphalt mixture. The study consists of three parts. The first part investigated material properties of cellulose and basalt fiber, including microscope electrical scanning. The second part conducted a series of tests to evaluate the effects of different combinations of cellulose and basalt fiber on performance. With a total addition of fiber 0.4% by the weight of mixture, five different cellulose‐basalt fiber ratios, 0 : 4, 1 : 3, 2 : 2, 3 : 1, and 4 : 0, were introduced to the asphalt mixtures. A series of tests including draindown, permanent deformation, low temperature bending, beam fatigue, and moisture damage resistance were conducted. In the final part, a benefit‐cost ratio was designed to help determine the optimum cellulose‐basalt fiber combination in the economic aspect. Results show that material properties of the two fibers are very different, including thermostability, modulus, surface, and microstructure, especially oil absorption. In general, all samples with fibers outperformed the control group in all the performance tests. Specifically, cellulose fiber improved draindown, ductility, and fatigue more significantly, whilst basalt fiber has more influence on improving permanent deformation, deflection strength, and stress sensitivity. Equal portion of cellulose and basalt fiber has the best moisture damage resistance. The mechanisms of the two fibers are different, resulting in different performance improvements on asphalt mixtures. Overall, an appropriate combination of the two fibers would produce paving materials with more balanced performance in an economical way.

There are known problems of dissolution, consistency of performance, segregation, and instability with the crumb rubber currently used in asphalt for road engineering. A silane coupling agent (KH550) solution was therefore used to pretreat the crumb rubber so as to improve its interfacial characteristics. The effects of KH550 on the properties of asphalt rubber were studied using high‐ and low‐temperature performance tests, temperature sensitivity test, and compatibility test. On the basis of these tests, the optimum concentration of KH550 pretreated crumb rubber is 1.0%. The surface properties and micromodifications of the treated crumb rubber were analyzed using scanning electron microscopy and an infrared spectrometer. The performance and economic benefit of the modified asphalt rubber was compared to styrene‐butadiene‐styrene (SBS) modified asphalt, and it was found that KH550 pretreated crumb rubber is able to significantly improve the high‐temperature performance of asphalt rubber, thus offering notable potential economic benefits.

The extensive use of cement has caused significant resource consumption and serious carbon emission problems. Recycling steel slag to partially replace cement presents a promising alternative. This study utilized steel slag powder (SSP) and steel slag aggregate (SSA) to prepare cement stabilized aggregate (CSA). The effects of different amounts of SSP and SSA on the road performance of CSA were studied, which was also compared with cement-fly ash (FA) stabilized aggregate (CFSA). The results demonstrated that adding SSP and SSA resulted in higher optimal moisture content and the maximum dry density of CSA. Adding 10% SSP enhances the mechanical properties of CSA. Compared to FA, SSP shows superior improvement effects at a 30% substitution rate. The dry shrinkage coefficient of CSA decreases as the SSP content increases. Further addition of SSA can further reduce shrinkage of CSA. The proper amount of SSP has no obvious effect on cement hydration, and the hydration degree of cement-SSP was higher than that of cement-FA. In addition, the higher the SSP blend, the lower the cost of the CSA and the lower the carbon emissions. Taking into account the performance, environmental impact, and cost of CSA, the optimal admixture of SSP is 30%.

Due to the research of Marshall test method in anti-cracking material, application is inadequate, in accordance with results of gyratory compaction test, different number of Marshall compaction test has been carried out. With porosity as the evaluation index, two-sided compaction 75 times can be used as the Marshall test optimum compaction times of anti-cracking layer material. Through the regression of gyratory compaction test and Marshall test results, and combined with the characteristics of anti-cracking material and related technical specification, the technical requirements for Marshall test on anti-cracking layer material were determined, and the optimal asphalt content was 7.5% which was close to gyratory compaction test result 7.6%. Those experimental results showed that the research of Marshall test evaluation method for anti-cracking material was definitely accurate and reliable. Study results can provide an important reference for determining the optimal asphalt content of anti-cracking material and the popularization and application of anti-cracking material in road reconstruction projects.