In this paper, the key technologies in the construction process of hot in-place recycling were investigated in order to improve the utilization rate of waste asphalt mixture; traditional lab tests including penetration, softening point and ductility tests, atomic force microscope test of recycled asphalt under different rejuvenator content, and the test of milling on grading at different temperatures were carried out. The influence of RAP content and rejuvenation processes on road performance were studied, and the low-temperature performance of mixture was analyzed by the energy analysis method, and the evaluation index was proposed. Test results indicated that the penetration and ductility increases, the softening point decrease with the rejuvenator content increasing, and the optimum rejuvenator content is 4%. The optimum mixing and compaction temperature will decrease by 2–6 °C on average for every 10% increase of RAP content by analyzing the mixture volume index. The results showed enhance rutting resistance of the mixture but lower moisture resistance and low-temperature crack resistance by adding the RAP content. The strain energy density of 10 KJ/m³ is proposed to evaluate the low-temperature performance of the mixture, and 30% RAP produces optimal mixture. The higher rutting resistance and moisture resistance can be obtained by using the construction process of RAP+ rejuvenator co-heating, and higher low-temperature crack resistance with RAP+ rejuvenator without heating.

As a new concrete crack patching technology, microbial self-healing slurries offer favourable characteristics including non-pollution, ecological sustainability and good compatibility with concrete. In this paper, a nano-sio₂-modified microbial bacteria liquid, combined with sodium alginate and polyvinyl alcohol, was used to prepare a nano-modified microbial self-healing slurry. This slurry was used to coat concrete under negative pressure in order to verify its restoration effect, and the micromorphology of the resulting microbial mineralization products was observed. The results revealed that patching the concrete using the nano-modified microbial slurry significantly improved its permeability, and increased its carbonization resistance by three times in comparison with the control group. Through a combination of Scanning electron microscopy (SEM) and X-ray diffraction (XRD) observation, it was determined that the microbial mineralization reaction products were mainly calcite crystals, which, integrated with the nano-sio₂, sodium alginate and polyvinyl alcohol at the microscopic level, filled the internal pores of concrete, thus improving its durability.

Prestressed concrete pavement can reduce slab thickness, eliminate transverse joints and enhance durability compared to traditional concrete pavement. Traditional prestressing or precast prestressing in the longitudinal direction requires additional space for anchorage and adds more joints. This study proposed an oblique prestress concrete pavement, in which prestressed tendons were distributed with an angle to the road direction so that the prestress can be applied in both the transverse and longitudinal directions. The detailed design of the oblique prestress concrete pavement, including the selection of raw materials, design of cement concrete, anchorage area, size and distribution of prestressed tendons, stress analysis within the concrete slab, sliding layer, side reinforcement, and regular reinforcement at top and bottom are all included in this study. The slab thickness, diameter, distribution angle, and spacing of tendons were obtained based on the stress analysis to meet the requirement of fracture criteria and fatigue criteria. A demonstrative road pavement section, which has performed well after three years of traffic opening, was constructed according to the design. A step-by-step description of the construction was also presented in the study.

In this study, the effects of recycled sand (RS) carrying sulfate corrosion media on mortar drying and autogenous shrinkages were investigated. Four variables were considered, the replacement percentage of RS, water to cement (W/C) ratio, secondary cementitious material, and the corrosion concentration of RS. The test results indicated that the replacement percentage of RS was positively related to the drying and autogenous shrinkages of the mortar. The drying shrinkage of the mortar increased with an increase in the W/C ratio, while the autogenous shrinkage showed an opposite trend. The addition of fly ash (FA) had a significant inhibitory effect on the drying and autogenous shrinkages of the mortar. The drying shrinkage of the mortar was reduced, while the autogenous shrinkage was increased by adding granulated blast-furnace slag (GBFS). The addition of both FA and GBFS caused an increase in the autogenous shrinkage. As the corrosion concentration of RS increased, the drying and autogenous shrinkage values decreased slightly. The scanning electron microscopy and X-ray diffraction analysis results showed that the corrosion products formed by the reaction of sulfate ions carried by RS and cement hydration products filled the internal pores of the mortar and slowed down the shrinkage of the mortar.

Under the background of the digital age, the curriculum development of vocational education is facing unprecedented opportunities and challenges. This paper takes “Engineering Project Management” course as an example to discuss the whole process reconstruction of vocational education digital transformation curriculum development. Through the in-depth analysis of the current situation of the curriculum, combined with the theory and practice of digital teaching, this paper puts forward a set of systematic curriculum reconstruction scheme, and carries on the application and evaluation in practical teaching. The research finds that digital transformation can significantly improve students’ learning effect and vocational ability, and provide a useful reference for vocational education curriculum reform.

With the development of the new generation of information technology such as artificial intelligence, Internet of Things and big data, digital transformation and intelligent construction have become the inevitable trend of high-quality development of highways. The traditional talent training structure and quality of highway and bridge major in higher vocational colleges can not meet the new needs of the industry development, we must through the deep integration of “AI+” knowledge, adjust and innovate the talent training mode, in order to cultivate the road and bridge professional high-skill talents to adapt to the background of digital intelligence.