This study is focused on the effect of basalt fiber on the road performance of the asphalt mixture. The road performance of asphalt mixture with different dosages of basalt fiber was comprehensively evaluated using Marshall Stability test, the wheel tracking test, the three-point bending beam test and the freezing-thaw splitting test. The road performance of lignin fiber reinforced asphalt mixture and polyester fiber reinforced asphalt mixture also were tested to compare with the road performance of basalt fiber reinforced asphalt mixture. The results showed that basalt fiber can enhance mechanical properties, the low-and high-temperature performance and water sensitivity of the asphalt mixture significantly. Considering the road performance and economic benefits, the appropriate dosage of basalt fiber is about 0.3%. Marshall Stability (MS), dynamic stability (DS), the maximum bending strain and the tensile strength ratio (TSR) of asphalt mixture with 0.3% basalt fiber were increased by 19.6%, 25.5%, 22.2% and 6.0%, respectively. Basalt fiber has certain advantages in improving the low-temperature performance of asphalt mixture by comparison with lignin fiber and polyester fiber.

The performance of an asphalt mixture will deteriorate under the condition of salt erosion, but there are different opinions on the mechanism of deterioration. Few studies have focused on the relation between the change of void characteristics and performance deterioration of an asphalt mixture exposed to salt erosion. To explore the relation between the air voids characteristics of an asphalt mixture and mechanical damage under salt erosion, the mechanical damage in an asphalt mixture was measured by splitting strength. The asphalt mixture specimens, immersion solutions, asphalt mortar, and aggregate were scanned with CT technology. To segment the voids, the Otsu method was used over asphalt mortar and solution range of CT values. A three-dimensional reconstruction of the CT image was performed with Mimics 20 software to calculate the asphalt mixture’s void characteristics. On this basis, the relationships between the change in void characteristics and splitting strength were analyzed. The results showed that the ideal calculated void fraction can be obtained by threshold segmentation of the image void/asphalt mortar interface with the local CT value Otsu method. Under the salt corrosion environment, the increase of open voids of an asphalt mixture is linearly correlated with the decrease of splitting strength, while salts’ crystallization in the open voids produces crystallization pressure, accelerating the volume growth of open voids. The early damage of an asphalt mixture suffered from the salt may be mainly physical damage. These results can provide a useful reference for the performance of damage research on asphalt mixtures in salt enrichment areas.

Lignin fibers typically influence the mixture performance of stone matrix asphalt (SMA), such as strength, stability, durability, noise level, rutting resistance, fatigue life, and water sensitivity. However, limited studies were conducted to analyze the influence of fibers on the percent voids in mineral aggregate in bituminous mixture (VMA) during the mixture design. This study analyzed the effect of different fibers and fiber contents on the VMA in SMA mixture design. A surface-dry condition method test and Marshall Stability test were applied on the SMA mixture with four different fibers (i.e., flocculent lignin fiber, mineral fiber, polyester fiber, blended fiber). The test results indicated that the bulk specific gravity of SMA mixtures and asphalt saturation decreased with the increasing fiber content, whilst the percent air voids in bituminous mixtures (VV), Marshall Stability and VMA increased. Mineral fiber had the most obvious impact on the bulk specific gravity of bituminous mixtures, while flocculent lignin fiber had a minimal impact. The mixture with mineral fiber and polyester fiber had significant effects on the volumetric properties, and, consequently, exhibited better VMA over the conventional SMA mixture with lignin fiber. Modified fiber content range was also provided, which will widen the utilization of mineral fiber and polyester fiber in the applications of SMA mixtures. The mixture evaluation suggested no statistically significant difference between lignin fiber and polyester fiber on the stability. The mineral fiber required a much larger fiber content to improve the mixture performance than other fibers. Overall, the results can be a reference to guide SMA mixture design.

This study was intended to evaluate how citric acid influences the time-dependent rheological properties of magnesium oxychloride cement (MOC). For this purpose, rheological parameters, setting time, electrodeless resistivity, crystal phases, morphology, hydration product, and compressive strength were investigated. The results show that the addition of citric acid can improve the time-dependent rheological properties of MOC pastes due to the retarding effect of the citric acid. The citric acid dosages of 0.15, 0.25, and 0.35% can stabilize the rheological properties of MOC paste in 1, 2, and 3 h, respectively. The addition of citric acid prolonged the setting stage by introducing free ${\mathrm{H}}^{+}$ that weakened the flocculated structure of MOC paste and delayed the formation of $5\mathrm{MgO}·{\mathrm{MgCl}}_2·8{\mathrm{H}}_2\mathrm{O}$ . The early compressive strength was significantly decreased with increasing dosages of citric acid; however, the citric acid had less of a negative effect on the late compressive strength.

In order to ensure the safety of traffic, asphalt pavement is commonly required to utilize aggregates with excellent anti-abrasion property. This results in the lack of high-quality aggregates. The incorporation of solid waste in the aggregates is regarded as a high potential alternative for solving this problem. Since its material properties, such as rough surface, high Polished Stone Value (PSV) and the excellent adhesion property of asphalt, Basic Oxygen Furnace (BOF) slag can effectively improve the skid resistance of asphalt mixtures. First, the material properties of BOF slag are reviewed in this study. Then, the skid resistance of asphalt mixtures and aggregates are commendably evaluated by the Polished Stone Value test, Wehner/Schulze Tester, Aachen Polishing Machine, British Pendulum Test and Sand Patch test. The physical and mechanical properties of BOF slag play a key role in asphalt mixtures. This review found that the skid resistance mechanism of the BOF slag asphalt mixture is governed by factors such as BOF slag properties, incorporation methods and gradation types. Finally, the economic and environmental benefits of BOF slag asphalt mixtures were discussed. In addition, the function of gas catalysis and the melting of ice and snow can be added to the BOF slag asphalt mixture for a cleaner development in engineering. Furthermore, the existing problems, research directions and corresponding measures in this field are directed towards more durable and functional asphalt pavement construction.

In order to evaluate the macro-mechanical performance of asphalt mixture suffered from the sulphate–water–temperature–load coupling action, the self-designed asphalt mixture dynamic water–salt attack apparatus was adopted for the accelerated simulation of real service conditions in sulphate enrichment environment. Splitting test at room temperature and low temperature was conducted for assessing the performance of asphalt mixture suffered from still water immersion and multi-factor coupling action. Then the performance damage characteristics of asphalt mixture under different conditions were explored. The multi-linear regression analysis and t-test were applied to determine the significance of factors on the performance of asphalt mixture. The performance deterioration mechanism of asphalt mixture exposed to dynamic water and sulphate attack was preliminarily analysed. The results show that the sulphate–water–temperature–load coupling action plays an important role in the macro-mechanical performance deterioration of asphalt mixture and dynamic water further accelerates the deterioration process of sulphate attack to asphalt mixture. The dynamic water scouring times, temperature and sulphate solution concentration have a significant impact on the performance of asphalt mixture. The decreasing adhesion between asphalt and aggregate, along with exterior/interior sulphate crystallisation erosion contributes the important inducement for the performance deterioration of asphalt mixture.