Asphalt mortar is a typical temperature-sensitive material that plays a crucial role in the performance of asphalt mixture. This study evaluates the high- and low-temperature performance of asphalt mortar based on the dynamic mechanical analysis (DMA) method. Temperature-sweep tests of asphalt mortars were conducted using the DMA method under fixed strain level, frequency, and heating rate conditions. The dynamic mechanical response curves, characteristic temperature, and other indices were obtained and used to investigate the high- and low-temperature performance of asphalt mortar. The results showed that the phase transition temperatures T₁, T₀, and T_g can be used to evaluate the low-temperature performance of asphalt mortar. Additionally, they had a good linear relationship, and the evaluation results were consistent. Meanwhile, T₂, E₆₀, and tan(δ)_max indicators can effectively evaluate the high-temperature performance of asphalt mortar. Asphalt plays a key role in the performance of asphalt mortar. Mortars with neat asphalt A70 and modified asphalt AR had the worst and best high- and low-temperature performances, respectively. Furthermore, the finer gradation improved the low-temperature performance of asphalt mortar, while the coarser gradation improved the high-temperature properties of modified asphalt mortars but had the opposite effect on neat asphalt A70.

The use of recycled polyester fiber (Re-PET) partially addresses the scarcity of non-renewable polyester (PET), but its thermal resistance in asphalt mixtures is relatively low. To enhance the reutilization and thermal resistance of Re-PET, it was modified through in situ growth grafting with tetrahedral nanoSiO₂. A novel nanoSiO₂ hybrid material (SiO₂/Re-PET) was successfully prepared, and the effects of the surface modification on the morphology and thermal resistance of the Re-PET were investigated with the examination of its mechanism of modification. The results demonstrated an increase in the surface roughness and specific surface area of SiO₂/Re-PET, as well as a higher melting point and structural stability compared to Re-PET. Subsequently, Re-PET and SiO₂/Re-PET asphalt mastics under a filler–asphalt ratio of 1.0 were prepared, and their classical and rheological properties were investigated and compared. The results indicated an increase in the softening point and shear strength of SiO₂/Re-PET asphalt mastic, as well as a significant improvement in its high-temperature performance. Furthermore, subsequent pavement performance tests revealed a significant improvement in the performance of SiO₂/Re-PET asphalt mixtures compared to Re-PET asphalt mixtures. Consequently, the findings of this research promote the recycling of Re-PET, ultimately advocating for the sustainability of pavement construction.

Shrinkage during hardening and curing is one of the largest challenges for the widespread application of metakaolin-based geopolymers (MKGs). To solve this problem, a silane coupling agent (SCA) and waterborne epoxy resin (WER) were used to synthesize MKG composites. The individual and synergistic effects of the SCA and WER on chemical, autogenous, and drying shrinkage were assessed, the modification mechanisms were investigated by microstructural characterization, and shrinkage resistance was evaluated by the chloride ion permeability of MKG composite coatings. The results showed that the SCA and WER significantly decreased the chemical shrinkage, autogenous shrinkage, and drying shrinkage of the MKG, with the highest reductions of 46.4%, 131.2%, and 25.2% obtained by the combination of 20 wt% WER and 1 wt% SCA. The incorporation of the organic modifiers densified the microstructure. Compared with the MKG, the total volume of mesopores and macropores in MKG-WER, MKG-SCA, and MKG-WER-SCA decreased by 11.5%, 8.7%, and 3.8%, respectively. In particular, the silanol hydrolyzed from the SCA can react with the opened epoxy ring of the WER and the aluminosilicate oligomers simultaneously to form a compact network and resist shrinkage during the hardening and continuous reaction of the geopolymer. Furthermore, the apparently lowered chloride ion diffusion coefficient of concrete (i.e., reduction of 51.4% to 59.5%) by the WER- and SCA-modified MKG coatings verified their improved shrinkage resistance. The findings in this study provide promising methods to essentially solve the shrinkage problem of MKGs at the microscale and shed light on the modification mechanism by WERs and SCAs, and they also suggest the applicability of MKG composites in protective coatings for marine concrete.

In order to evaluate the feasibility of using hard-grade asphalt concrete in China’s highway construction, based on the accelerated loading test of the full-scale track of the Research Institute of Highway Ministry of Transport (RIOHTrack), the long-term service performance of hard-grade asphalt concrete base pavement was studied, and its actual service effect was evaluated. The study found that hard-grade asphalt concrete has higher strength, modulus and high-temperature stability. Although the low-temperature performance is generally not as good as that of asphalt, with a penetration grade (PG) of 60/80, it has equivalent or better cracking resistance in the area where the RIOHTrack is located. During the five-year observation period, the rutting deformation of the pavement structure showed an annual fluctuation increase. In comparison, the rutting resistance of a hard-grade asphalt concrete base structure can be increased by approximately 16%, and the deflection value is smaller, so the long-term performance of the anti-rutting effect and structural bearing capacity are better. The study shows that hard-grade asphalt concrete base pavement is suitable for highway construction in parts of China, where the climate is similar to that of the RIOHTrack location, or the temperature is higher or the latitude is lower.

To develop a cost-effective, high-viscosity asphalt for porous asphalt pavement, we utilized SBS, tackifier, and solubilizer as the main raw materials, identified the optimal composition through an orthogonal experiment of three factors and three levels, and prepared a low-cost high-viscosity asphalt. We compared its conventional and rheological properties against those of rubber asphalt, SBS modified asphalt, and matrix asphalt, employing fluorescence microscopy and Fourier transform infrared spectroscopy for microstructural analysis. The results indicate that the optimal formula composition for high-viscosity asphalt was 4–5% styrene-butadiene-styrene (SBS) + 1–2% tackifier +0–3% solubilizer +0.15% stabilizer. The components evenly dispersed and the performances were enhanced with chemical and physical modification. Compared with SBS modified asphalt, rubber asphalt, and matrix asphalt, the softening point, 5 °C ductility, and 60 °C dynamic viscosity of high-viscosity asphalt were significantly improved, while the 175 °C Brookfield viscosity was equivalent to SBS modified asphalt. In particular, the 60 °C dynamic viscosity reaches 383,180 Pa·s. Rheological tests indicate that the high- and low-temperature grade of high-viscosity asphalt reaches 88–18 °C, and that high-viscosity asphalt has the best high-temperature resistance to permanent deformation and low-temperature resistance to cracking. It can save about 30% cost compared to commercially available high-viscosity asphalt, which is conducive to the promotion and application of porous asphalt pavement.

In response to the complex pretreatment processes (e.g., solvent dissolution and high-temperature melting) of direct coal liquefaction residue (DCLR) in asphalt, its low-dosage limitation for high-value utilization in asphalt pavement, and the unclear interaction mechanisms between high-proportion DCLR and asphalt, this study comprehensively analyzed the molecular composition and structural characteristics of DCLR at multiple scales using FTIR, GPC, SEM, BET, Tg-FTIR, and XRD. DCLR was crushed to a particle size of 0.15 mm and mixed with 70# base asphalt at mass ratios of 10:100, 15:100, 20:100, 25:100, 30:100, 40:100, and 45:100 at 185 °C to prepare high-proportion DCLR-modified asphalt. The conventional and rheological properties of DCLR-modified asphalt at various dosages were evaluated and compared with those of Buton rock asphalt (BRA)-modified asphalt at equivalent dosages. The results indicated that DCLR and BRA significantly improved the high-temperature performance and PG grade of the base asphalt but reduced its low-temperature performance and grade. At equivalent dosages, DCLR exhibited a more pronounced enhancement in high-temperature performance and a greater reduction in low-temperature performance compared to BRA. High-proportion DCLR-modified asphalt meets the technical requirements for high-modulus asphalt. Using FTIR, GPC, four-component analysis, and elemental analysis, the chemical composition and performance variation trends of high-proportion DCLR-modified asphalt were investigated at multiple scales. The interfacial physical, chemical, and mechanical behaviors between DCLR and base asphalt were characterized. The interaction mechanisms between high-proportion DCLR and asphalt were elucidated, and a novel application strategy for DCLR in asphalt was proposed, significantly enhancing its resource utilization rate in road engineering.