Experimental measurements of the moisture diffusion and strength damage mechanism of dense asphalt mixtures

ABSTRACT

Moisture migration in pavement leads to the loss of strength of asphalt mixture. However, moisture profile measurement inside of the mixture can be challenging. In this paper, a new experimental method is proposed to measure the moisture profile; this method is based on the principle that white anhydrous copper sulfate powder turns blue with water. The influences of asphalt content, gradation, indoor compaction, temperature and pressure on moisture diffusion depth and strength loss are also discussed. The results show that the proposed method successfully reveals the moisture profile of the asphalt mixture. High temperature and pressure accelerate the moisture diffusion process. A large filler-bitumen ratio and high content of coarse aggregate result in a large diffusion depth. The rolling compacted mixture demonstrates better resistance to moisture diffusion than the Marshall mixture. It is inferred that the rainfall’s influence on the asphalt layer is mainly within a depth of 23 mm below the surface. The strength attenuation of asphalt mixture after damage is mainly affected by compaction method and external pressure, while filler-bitumen ratio affects the attenuation trend of the mixture strength. The proposed method in this paper has the advantages of easy operation and in-field application potential.

KEYWORDS:

• Moisture diffusion depth
• discolouration
• strength loss
• asphalt mixture

Disclosure statement

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

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [grant no 51508150, 52178266, 52208438].