Mixing carbon nanotubes with asphalt binder through a foaming process toward high-performance warm mix asphalt (WMA)

ABSTRACT

This paper investigates mixing carbon nanotubes (CNTs) with asphalt binder through a foaming process to produce high-performance warm mix asphalt (WMA). Two different solvents of ethanol and a water-based surfactant are used to disperse the multi-walled CNTs. Initial morphological assessment of the two CNT solutions showed that a more homogenous dispersion of the CNTs was achieved using the water surfactant solution. The foaming performance, thermal, and rheological properties of the foamed asphalt mixed with different percentages of CNTs are further investigated. The test results showed that a very small amount of CNTs (0.06% ∼ 0.1% in weight of the binder) can effectively enhance the foaming performance for bubble stability without tangibly increasing the rheological properties of the foamed asphalt. The specific heat capacity of the foamed samples was smaller than the neat binder, whereas the glass transition temperature of the foamed samples shifted to a lower temperature as compared to that of the neat binder. The thermal conductivity of the 6% CNTs sample (0.24% wt. in asphalt binder) was improved by two-fold compared with the foamed unmodified asphalt, which indicates the potential of using CNTs in the binder for enhancement of thermal properties in asphalt pavements.

KEYWORDS:

• Asphalt foaming process
• Carbon nanotube (CNT)
• Asphalt binder
• Warm mix asphalt (WMA)
• Rheological properties

Acknowledgment

This work is sponsored by the National Science Foundation CMMI 1301160, AF14-AT22, IIP #1738802, IIP # 1941244, and CMMI #1762891, whose support is gratefully acknowledged. The authors would also like to thank the Carleton Laboratory director and staff especially Dr. Liming Li, Mr. Ceaser Jefferson Chabla-Sarmiento, and Mr. Bhumipak Auewarakul for their contributions to the laboratory testing, and Mr. Jeff Xie for his help with manuscript preparation. The contents of this paper reflect the view of the authors, who are responsible for the facts and the accuracy of the data presented. This paper does not constitute a standard, specification, or regulation.

Disclosure statement

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

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by Air Force Office of Scientific Research: [Grant Number AF14-AT22]; Division of Civil, Mechanical and Manufacturing Innovation: [Grant Number 1301160, 1762891]; Division of Industrial Innovation and Partnerships: [Grant Number 1738802, 1941244].