During the service period, asphalt materials are affected by various natural factors, including heat, ultraviolet light, oxygen and moisture, etc., resulting in the reduction of pavement performance, the increase of pavement distress and shortening of service life. This study aims to investigate the aging performance of asphalt under multiple aging conditions of heat, UV and aqueous solution. Thermal-oxygen aging, UV aging and hydrostatic erosion tests were carried out sequentially on asphalt. The rheological properties, chemical structure and element composition of asphalt were characterized before and after aging, and the effect mechanism of multiple conditions was discussed. The results show that the multiple conditions of heat and UV can increase the rutting resistance and weaken the cracking resistance of asphalt. However, the effect degree of UV decreases gradually with the deepening of aging degree. Additionally, the effect of water on the physicochemical properties is less than that of UV; however, water can increase the sensitivity of physicochemical properties to UV. In summary, this study explored the short-term cycling effect of heat, light and water on asphalt and provided an idea for simulation test of asphalt under multiple aging condition.

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Investigation of the Rheological Properties and Chemical Structure of Asphalt under Multiple Aging Conditions of Heat, UV and Aqueous Solution

Calcium alginate capsules encapsulating rejuvenator are a promising self-healing technology for asphalt pavement, but the effects of different healing agents on the self-healing performance of asphalt concrete has not been considered. In view of this, this paper aimed at exploring the effects of calcium alginate capsules containing different healing agents on the self-healing properties of asphalt concrete. Three types of capsules with sunflower oil, waste cooking oil and commercial rejuvenator were fabricated via the orifice-coagulation bath method and the interior structure, mechanical strength, thermal stability and oil content of the prepared capsules were characterized. The healing levels of asphalt mixtures with different capsules under different loading cycles and stress levels were evaluated. Furthermore, the saturates, aromatics, resins and asphaltenes (SARA) fractions and rheological property of extracted asphalt binder within test beams with different capsules after different loading conditions were assessed. The results indicated that all the three types of capsules meet the mechanical and thermal requirement of mixing and compaction of asphalt mixtures. The healing levels of test beams containing vegetable oil capsules were higher than that of waste cooking oil capsules and industrial rejuvenator capsules. The strength recovery ratio and fracture energy recovery ratio of test beams with vegetable oil capsules reached 82.8% and 96.6%, respectively, after 20,000 cycles of compressive loading at 1.4 MPa. The fracture energy recovery ratio of the waste cooking oil capsules also reached as high as 90%, indicating that waste cooking oil can be used as the healing agent of calcium alginate capsules to improve the self-healing property of asphalt mixture. This work provides a significant guide for the selection of healing agent for self-healing capsules in the future.

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Self-Healing Properties of Asphalt Concrete with Calcium Alginate Capsules Containing Different Healing Agents

Exposure of construction workers to hazardous emissions in highway rehabilitation projects measured with low-cost sensors.

Exposure of construction workers to hazardous emissions in highway rehabilitation projects measured with low-cost sensors

Preparation and characterization of low flammable asphalt for tunnel pavements

Rheology and volatile organic compounds characteristics of warm-mix flame retardant asphalt

The invention discloses a cascade production and grading application method of steel slag sand. The cascade production method of the steel slag sand comprises the processes of pretreatment process, drying process, primary production process, secondary production process, finish machining treatment process and iron removal process, wherein crushing and first screening are carried out on steel slagraw materials in the pretreatment process to obtain steel slag sand fine aggregate; drying is carried out by a dryer in the drying process to obtain a dried steel slag sand material; second screeningand first negative pressure dust absorption treatment are carried out in the primary production process to obtain coarse sand; third screening and second negative pressure dust absorption treatment are carried out on the coarse sand in the secondary process to obtain primary sand; finishing and polishing are carried out on the primary sand to obtain high quality sand, and iron removal is carried out on the steel slag sand through arranging multiple sets of electromagnetic iron removal devices in the iron removal process. According to the cascade production process provided by the invention, three kinds of steel slag sand products with different fineness modulus and suitable to different applications can be obtained, and part of natural river sand can be replaced with the products.

Ren Yanfei

Papers

Rheology and volatile organic compounds characteristics of warm-mix flame retardant asphalt

Cascade production and grading application method of steel slag sand