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One of the primary deteriorations in asphalt pavement is thought to be the asphalt's low-temperature cracking performance.
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However, there isn’t much research on how well asphalt performs at low temperatures when exposed to both heat and light.
In order to explore the low-temperature cracking performance under heat and light simultaneously based on the climatic circumstances of China, the ductility test, bending beam rheometer (BBR) test, and asphalt composition analysis test are combined.
This study generated styrene-butadiene-styrene block copolymer (SBS)-modified asphalt binders using several modifier types and base asphalt.
The findings demonstrate that heat and light combination weaken asphalt's low-temperature cracking resistance. It is noticeably lessened in the early stages, and it worsens as time, temperature, and ultraviolet (UV) intensity grow.
The low-temperature cracking performance of asphalt is significantly influenced by its composition, and the SBS modifier can increase asphalt's resistance to low temperatures.
The low-temperature cracking performance of asphalt can be enhanced by the intelligent selection of base asphalt and modification.
Whether base asphalt or modified asphalt, under heat and light together, the change patterns of their ductility and component content are comparable.
As a result, it is advised to use the ductility of asphalt aged by heat and light together for 15 days as the evaluation index of the low-temperature cracking performance of asphalt and to choose asphalt.
in accordance with the temperature and UV intensity of the asphalt pavement use area in order to improve the anti-cracking ability of the asphalt pavement.
Surface water will seep into the pavement as a result of cracks in the asphalt, leading to several problems such as looseness, potholes, and stripping.
Steps, slurry pumping, and mesh cracking are just a few problems that might result from water entering the pavement because it will also soften the base course and the subgrade.
Cracking shortens the lifespan of asphalt pavement and speeds up pavement degradation. Researchers studied the cracking of asphalt pavement and asphalt mixture extensively to address the failure of the asphalt pavement.
due to cracking. According to Mao's research on the crack initiation and behavior of crack propagation in asphalt pavements, the mechanism for crack propagation was predominantly tensile.
In a seasonal frozen area, Yan researched the top-down cracking mechanism and preventative measures on a flexible base asphalt pavement and discovered that traffic load, environmental conditions, and asphalt aging were the primary.
causes. According to Donna et alresearch.'s on the causes, impacts, and treatments of top-down cracking in asphalt pavement, the mixture with a higher asphalt percentage would not be as prone to segregate.
Wang examined the asphalt pavement's crack issue as a result of UV light aging and asserted that the effect of UV made asphalt pavement more prone to cracks. Ramos et al.
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examined existing techniques for determining asphalt binders' susceptibility to fatigue damage and proposed their own approach.
According to Wu et al.'s assessment of the aging effect of UV radiation on the asphalt mixture, UV radiation significantly.
affected the asphalt concrete's semi-circular bending strength, decreased its bending strength at 10 °C, and made the aging effect more noticeable the longer the exposure time was. Behnia et al.
evaluated the methodology for assessing the low-temperature cracking performance of asphalt and discovered that acoustic emission may do so.
Although numerous studies on the cracking of asphalt pavement and asphalt mixture have been conducted, research rarely focuses on the interaction of heat and light.
On the other hand, numerous studies have been done to determine how well asphalt materials work at low temperatures.
Several investigations used the asphalt's low-temperature performance and evaluation approach, but they did not take into account the combined effects of light and heat.
The anti-cracking properties of asphalts modified with styrene-butadiene-styrene (SBS) were investigated by Zhou et al.
utilizing the rolling thin film oven (RTFO) and pressure aging vessel (PAV) residue based on SHRP techniques. In the range of higher temperatures, it was found that there was a strong association between the complex shear modulus, phase angle, fatigue cracking factor, creep stiffness, m value, and temperature.
It was discovered that the critical block-cracking zone could be reached by the two routes, with the oxidative effect that occurs in the field being more apparent in the UV radiation route.
Patrcia et al. aged three modified and nine unmodified asphalt binders using different testing methodologies, i.e., a UV route and a thermal route with changing exposition time.
The carbonyl index displayed generally higher values than the other aging techniques and was extremely susceptible to UV aging.
At moderate and low-temperature ranges, Zhang et al. evaluated the impact of long-term laboratory aging on the rheological characteristics and cracking resistance of polymer-modified asphalt binders and.
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examined various evaluation indices. By comparing the compositional elements, structural elements, and chemical properties of asphalt binder before and after aging, Glotova et al.
investigated the impact of UV aging on an asphalt binder. The findings revealed a strong correlation between the type of light exposure and the rate of photo-oxidation aging, and that UV radiation had clear.
degenerative effects on these properties. Zhang et al. studied the aging impacts of three different aging techniques: UV radiation, pressure aging vessel (PAV), and thin film oven test (TFOT).
They discovered that PAV aging and UV aging have more pronounced effects on the breakdown of the styrene-butadiene-styrene (SBS) polymer.
The findings demonstrated that with aging, the examined binders tended to become harder and more viscous at relatively low loading frequency, and their capacity to reduce internal stress decreased.
The surface layer of asphalt pavement becomes stiffer and more brittle when exposed to UV radiation, which also plays a significant role in the photooxidation of bitumen.
However, very little research has been done to date on how heat and light combinations affect asphalt's cracking resistance.
In actuality, the anti cracking performance of asphalt pavement is significantly influenced by the asphalt's low-temperature cracking resistance.
Meanwhile, heat and light have an impact on the fracture resistance of asphalt during the installation and service life of an asphalt pavement since asphalt is temperature sensitive.
In order to replicate the long-term aging behavior and the short-term thermo-oxidative aging of bitumen, the PAV test and the RTFOT (Rotary thin film oven test) are often employed worldwide.
The link between actual pavement aging and PAV simulation aging, however, is not significant because UV light was ignored.
There is currently relatively little knowledge on how asphalt cracks when heat and light are combined. The low-temperature cracking performance of asphalt under heat and light in combination must thus be thoroughly.
investigated based on the environmental factors of asphalt pavement in order to solve the problem of cracking asphalt pavement.
The 501s branching and 4402 linear SBS modifiers utilized in the study were created by Dongguan Yuetai New Material Co.,
Ltd., Guangdong, China, and their distinguishing characteristics are tested. As the basis asphalt samples, Zhonghai AH-70 (ZH-70) and South Korea AH-70 (SK-70) asphalt were used;
The dosage of SBS modifiers in modified asphalt was set at 5% in accordance with the results of the available research and economics.
An FM300 High Shear Dispersing Emulsifier was used to prepare the modified asphalts (FLUKO, Shanghai, China). The basic asphalt was preheated to 170-180 °C in a small container before being sheared with the dispersing emulsifier.
The 501s branched or 4402 linear modifier was then gradually added to the base asphalt in accordance with the desired dose.
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The mixture was heated to 175 to 180 °C and kept there while being melted and stirred for 30 minutes. After that, the mixture was agitated for.
40–60 minutes at 175–180 °C using a high-shear mixer at a shearing rate of 300–5000 r/min. The mixture was finally baked for two hours at 175 °C.
In accordance with ASTM D2872, short-term aging handled by RTFO (85 min, 163 °C, and airflow at 4 L/min) was used to imitate the aging that asphalt faces during asphalt construction.
PAV aging was used to replicate the long-term aging that asphalt experiences while being used as pavement (air pressure at 2.1 MPa).
It illustrates the use of an independently produced RG-80 asphalt aging test chamber for the combined long-term aging of asphalt under heat and light.
The maximum temperature of the aging test was established at 70 °C in consideration of the average maximum ground temperature of 65 to 75 °C in China and the significant heat-absorbing properties of asphalt pavement.
The high-pressure mercury lamp with a radiation spectrum spanning from 250 to 440 nm was used as the light source of the RG-80 asphalt aging test chamber because it was known that UV.
radiation from sunlight, which has a wavelength range of 260-410 nm, accelerates the aging of asphalt pavement.
The UV365 UV radiometer was used to measure the UV intensity, which was controlled by the high-pressure mercury lamp's power, amount, and voltage (Beijing Normal University Photoelectric instrument Company, Beijing, China).
The longest duration of 15 days and the maximum UV intensity of 40 W/m2 were chosen for the aging test based on the findings of the prior study by Zhang and Ran.
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A flat bottom disc with an inner diameter of 140 mm and a height of 9.5 mm was used to hold the melted asphalt for the aging test in order to meet the UV light aging requirement. The asphalt weight of the flat bottom disc was 30 g.
Within the first five days of age, their ductility values fell sharply, and as the aging period went on, they fell steadily. The ductility maintained rate varied depending on the type of asphalt, and when compared to the base asphalt, the modified asphalt's ductility value was much higher.
The ductility values of the 15-day aging time for ZH-70 asphalt, ZH-70 linear-modified asphalt, ZH-70 branched-modified asphalt, SK-70 asphalt, SK-70 linear-modified asphalt, and SK-70 branched-modified asphalt were, respectively, 4 cm, 42 cm, 29 cm, 3 cm, 17 cm, and 11 cm.
The ductility retained rates of the 15-day aging time were 9%, 47. The ductility value of modified asphalt for various base asphalts varied for the same modifier.
At the 15-day aging time, the linear-modified asphalt and branched-modified asphalt in ZH-70 had ductility values that were 10.5 times higher and 7.25 times higher, respectively, than those of the base asphalt.
and the linear-modified asphalt and branched-modified asphalt in SK-70 had ductility values that were 5.66 times higher and 3.66 times higher, respectively.
Additionally, various bases had varied ductility values for the same modifier. The ductility values of the 501s branched modifier and the 4402 linear.
modifiers of asphalt modified with ZH-70 after 15 days were 2.47-fold and 2.64-fold higher than those of asphalt modified with SK-70, respectively. The potential cause of the discrepancy was the varied chemical makeup of the base asphalt.
The results of the ductility test show that heat and light have a significant impact on the asphalt's low-temperature cracking ability and that they can diminish that performance early on.
Additionally, the resistance of the asphalt to low-temperature cracking is diminished the higher the temperature and UV intensity values are.
The choice of base asphalt and modifier judiciously can enhance the low-temperature cracking performance of asphalt.
The type of asphalt has a significant impact on the low-temperature cracking performance of asphalt under heat and light combined.
In order to test the low-temperature cracking performance, six different types of asphalt were subjected to heat and light simultaneously for 5, 7, and 15 days. The results of this experiment led to the following conclusions.
The ductility value of asphalt decreased when heat and light were combined, and it became more apparent within 5 days.
The ductility value of modified asphalt was significantly higher than that of base asphalt, and for the same modifier, the ductility value of modified.
asphalt for different base asphalts was also different, showing that the asphalt cracking resistance was obviously reduced at the early stages.
A sensible choice of base asphalt and modifier could enhance the low-temperature cracking performance of asphalt, and it also gets worse with increased aging time, temperature, and ultraviolet intensity.
The creep stiffness S value of asphalt dramatically rose when heat and light were combined with it, whereas the creep stiffness change rate m value of asphalt clearly decreased as aging time increased.
In contrast, the S value and m value change rates of modified asphalt were lower than those of basal asphalt.
As a result, heat and light combined with aging could dramatically reduce the low-temperature cracking resistance of asphalt, whereas they had less of an impact on modified asphalt.
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While the concentration of aromatics definitely dropped as the product aged longer, the content of asphaltenes dramatically rose when heat and light were combined.
In comparison to basic asphalt, modified asphalt had decreased asphaltene and aromatic change rates.
The four components' contents clearly changed after just five days of aging, and as the aging process continued, their change rates slowed.
The asphalt's low-temperature cracking ability was directly influenced by its composition. Whether it was base asphalt or modified asphalt, the ductility and component content change trends were identical under heat and light.
As a result, it was suggested that the ductility of asphalt aged by heat and light together for 15 days be used as the evaluation index of the asphalt's low-temperature cracking performance.
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