Recycled asphalt pavement (RAP) can be used in highway engineering again by cold recycled technology. Due to the aged asphalt on the surface of RAP, some problems such as poor adhesion between emulsified asphalt and RAP and the low properties of emulsified asphalt recycling mixture are easy to occur. This work aims at analyzing the aging degree of asphalt from RAP surface and improving the poor adhesion between RAP and emulsified asphalt by modifying the surface characteristics of RAP. In this work, a new device was designed to delaminate off the asphalt on the surface of RAP. The aging degree of asphalt at different layers was studied then by physical properties and molecular weight distribution. Slurry of hydrated lime (Ca(OH)₂) (S‐Ca) and slurry of silane coupling agent (SCA) modified Ca(OH)₂ (S‐Si‐Ca) were used to modify the asphalt on the surface of RAP, respectively. The adhesion between emulsified asphalt and RAP was studied by contact angle and boiling method. Results show that the asphalt on the RAP surface can be successfully stripped into four layers through the self‐designed RAP delaminating and stripping device. The aging degree of asphalt wrapped around the surface of the RAP showed a tendency to be gradually severe from outside to inside. However, asphalt at the innermost layer (L4) shows abnormal situation due to the fact that the light components are absorbed by the aggregate. In addition, reasonable dosage of SCA is determined as 3.0% in Ca(OH)₂ powder mass. Both S‐Ca and S‐Si‐Ca can effectively reduce the contact angle and thus improve the adhesion between emulsified asphalt and RAP. Moreover, S‐Si‐Ca possesses the most obvious modification effect attributed to the formation of asphalt‐SCA‐Ca(OH)₂ structure.

The effects of fly ash, sodium carbonate content, foaming temperature and foaming time on foam glass aperture sizes and their distribution were analyzed by the orthogonal experimental design. Results from the steady-state method showed a normal distribution of the number of apertures with change in average aperture, which ranges from 0.1 to 2.0 mm for more than 93% of apertures. For a given porosity, the thermal conductivity decreases with the increase of the aperture size. The apertures in the sample have obvious effects in blocking the heat flow transmission: heat flow is quickly diverted to both sides when encountered with the aperture. When the thickness of the sample is constant, the thermal resistance of the foam glass sample increases with increasing porosity, leading to better thermal insulation. Furthermore, our results suggest that the more evenly distributed and orderly arranged the apertures are in the foam glass material, the larger the thermal resistance of the material and hence, the better the thermal insulation.

The incorporation of desert sand-mineral admixture improves the abrasion resistance of concrete. To prolong the service life of assembled concrete channels and mitigate the depletion of river sand resources, the effects of fly ash (FA), silica fume (SF), desert sand (DS), and basalt fiber (BF) on the mechanical properties and the abrasion resistance of concrete were examined, alongside an analysis of their microstructures to elucidate the underlying mechanisms of influence. The results indicated that the abrasion resistance strength of concrete mixed with 10% FA and 0.05% BF alone increased by 80.19% and 81.59%, respectively, compared with ordinary concrete (OC). When SF was added to the concrete at a dosage of 10%, it improved the mechanical properties and the abrasion resistance of the concrete. Furthermore, adding SF resulted in a 12.50% increase in compressive strength and a 12.27% increase in abrasion resistance strength compared to OC. The addition of DS did not significantly enhance the concrete’s abrasion resistance. The combination of ingredients for desert sand concrete (DSC) that provides excellent abrasion resistance was determined using an orthogonal experiment. The optimal mixture consisted of 10% FA content, 10% SF content, 40% DS content, and 0.05% BF content, which increased the abrasion resistance strength by 112.95% compared to OC. Through microscopic analysis, it is found that the width of the interfacial transition zone (ITZ) is an important factor in determining the abrasion resistance of concrete, and a narrower ITZ enhances the concrete’s abrasion resistance. The study’s findings could function as a theoretical reference for the engineering design of DSC.

To enhance the physical and mechanical characteristics of steam-cured concrete, an orthogonal experimental design was utilized to examine the effects of varying contents of fly ash (0 wt%, 10 wt%, 15 wt%, 20 wt%), silica fume (0 wt%, 5 wt%, 10 wt%, 15 wt%), basalt fiber (0 vol%, 0.05 vol%, 0.1 vol%, 0.2 vol%), and polypropylene fiber (0 vol%, 0.05 vol%, 0.1 vol%, 0.2 vol%) on its mechanical properties. Utilizing range and variance analyses, this study identified four preliminary optimized compositions of concrete incorporating fly ash, silica fume, basalt fiber, and polypropylene fiber. On this basis, in order to determine the optimal mix proportion, the mechanical performances, the pore characteristics, and the microstructure of four optimized mix proportions were analyzed. According to the results of macroscopic, fine, and microscopic multi-scale tests, the addition of 15 wt% fly ash, 10 wt% silica ash, 0.2 vol% basalt fiber, and 0.1 vol% polypropylene fiber to the steamed concrete is the best to improve the performance of the steamed concrete. Compared to ordinary concrete, the compressive strength increases by 28%, the tensile strength increases by 40%, and the porosity decreases by 47.2%.

An experimental study was performed to investigate the shear strength of concrete beams made with dune sand (DS) from the Gurbantunggut Desert in the Chinese province of Xinjiang. The test consisted of 3 series of beams which explored the shear properties of dune sand concrete (DSC) beams. The failure mode, crack pattern, load deflection, and stirrup strain were investigated. Meanwhile, the effect of shear span‐to‐depth ratio (a/d), stirrup ratio, and dune sand replacement ratio on the shear strength of DSC beams was discussed. The results showed that the dune sand replacement ratio had insignificant influence on the failure mode of beams, so it was feasible to use DS to fabricate beams in regions of Xinjiang in China. Furthermore, the measured shear strengths of the DSC beams were compared with the calculated values of current design codes, and the results indicated that the shear strength of DSC beams was not precisely predicted by current design codes. Therefore, a modified formula was proposed to calculate the shear strength of DSC beams.