# Evaluation of Anti-Skid Performance of Asphalt Mixture Based on Accelerated Loading Test
## 3 Result and Discussion
### Texture Depth Test
Scheme S12, an SMA-10, has a smaller nominal maximum particle size compared to S7 and a larger oil-stone ratio. As a result, the initial pendulum value of S12 is lower than that of S7. As the loading test progressed, the pendulum values of the six SMA anti-skid surface layers gradually decreased, but the attenuation trend was not the same as that of AC-16. In the initial loading stage (before 5000 times), S7 and S11 exhibited an increasing trend in the pendulum value, followed by a decay. This phenomenon can be attributed to the fact that, in the beginning, the texture of the road surface was covered by an asphalt film, resulting in a lower initial pendulum value. As the tires move and water washes over the road surface, the asphalt film partially peels off, exposing the aggregate texture that starts to resist skidding. Generally, the pendulum value of each scheme oscillated in a wave-like pattern between 10,000 and 400,000 loadings. This behavior can be linked to the asphalt film on the road surface wearing off after a certain number of loadings and the continuously wearing bumps and peaks on the road surface. During this time, the anti-skid performance of the road surface is determined by the micro-texture of the aggregate. The friction coefficient of the road surface is in a stable state. The road surface of SMA is relatively rough, which can affect the pendulum value test and result in a wave-like decline in the pendulum value. After 400,000 loadings, the friction coefficient of SMA stabilizes. This phenomenon can be attributed to the fact that after the road surface texture is worn to a certain extent, both the macro and microtextures stabilize. Upon completion of a 600,000-time loading test, S11, which utilized andestite aggregate, exhibited the highest pendulum value after stabilization. This can be attributed to the superior mechanical properties of its coarse aggregate, as evidenced by its polishing value, crushing value, and abrasion value. Following the stabilization of AC-16, the pendulum value law of S11 is consistent with that of the former. On the other hand, S7, S8, and S9 comprised SMA-13 with varying oil-stone ratios. As the oil-stone ratio increases, the stable pendulum value decreases, a trend that is not in line with the stable pendulum value of AC-16. This indicates that the oil-stone ratio significantly impacts the stable value of the pendulum of the SMA-13. Compared to S7, the gradation of S10 is thicker, with a stable pendulum value similar to that of S7 after stabilization. Furthermore, the pendulum value of S12 (SMA-10) after stabilization is slightly smaller compared to that of S7 (SMA-13). This is consistent with the principle that larger nominal particle sizes produce better anti-skid durability. Regarding the pendulum value attenuation rate index, S11 exhibits the lowest rate of attenuation, which can be attributed to the high polishing value, low crushing value, and high abrasion value of the aggregate used. In summary, the results demonstrate that after 600,000 loadings, the average pendulum attenuation rates for the six groups of AC-16 and the six groups of SMA were 31.8% and 22.1%, respectively. This indicates that the SMA asphalt mixture exhibits superior anti-skid durability compared to the AC asphalt mixture.