Mechanism, prevention and remedy of alkali-pumping in new constructed asphalt pavement

ABSTRACT

The issue of alkali-pumping has emerged in recent years raising concerns on the quality of the newly constructed asphalt pavement. To understand alkali-pumping and its effects, we conducted two-year on-site inspection of a pavement and analysed the mineral composition of alkali-pumping. The water permeability, void characteristics, and water stability of the asphalt pavement with and without alkali-pumping were tested and compared. Then, we preliminary analysed the mechanisms. Furthermore, the probability of the alkali-pumping and its control method. Lastly, 3D ground-penetrating radar was utilised for analysing the relationship between the dielectric constant and the distribution of alkali-pumping. Subsequently, dielectric constant thresholds corresponding to alkali-pumping were established. The results showed that alkali-pumping is caused by the segregation of the pavement and the leakage of alkali elements. Furthermore, the dielectric constants with and without alkali-pumping were significantly different, and their spatial distribution was well correlated with the occurrence of alkali-pumping. Finally, it was determined that asphalt pavements with a dielectric constant smaller than 3.5 are likely to experience alkali-pumping, while those with a dielectric constant between 3.5 and 6.5 are unlikely to experience alkali-pumping, and in those with a dielectric constant greater than 6.5, the probability of alkali-pumping is negligibly small.

KEYWORDS:

• Alkali-pumping
• mechanisms
• ground-penetrating radar
• dielectric constant
• probability

Acknowledgments

The authors sincerely acknowledge the National Natural Science Foundation of China (NSFC 51678251); the support of South China University of Technology; the support of Xiaoning Roadway Institute of Engineering. Author contributions: Conceptualization, Weixiong Li, Duanyi Wang, and Chunlong Xiong; Data curation, Bo Chen, and Xianshu Yu; Formal analysis, Weixiong Li, Duanyi Wang, Jiangmiao Yu, Chunlong Xiong, and Bo Chen; Funding acquisition, Jiangmiao Yu; Investigation, Xianshu Yu; Writing – original draft, Chunlong Xiong and Xianshu Yu; Writing – review & editing, Chunlong Xiong, Weixiong Li, Duanyi Wang and Jiangmiao Yu.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors sincerely acknowledge the National Natural Science Foundation of China (NSFC 51678251).