Influence factors of strength and performance of foamed asphalt cold recycled mixture

Abstract

This paper investigates the factors that influence the strength and moisture damage resistance of foamed asphalt cold recycled mixtures. The relevant factors include gradation, asphalt penetration, mixing temperature, particle size of virgin aggregates, and the curing time and moisture content. Indirect tensile strength (ITS) tests under dry and wet conditions were conducted to evaluate the mixture properties. The test results indicated that minute variation in foaming parameters (i.e. expansion ratio and half-life) for asphalt binders with different penetration grades, had no significant effect on the strength and performance of foamed asphalt cold recycled mixtures. The results also revealed that the mixture with medium-grained gradation exhibited higher ITS than mixtures with coarse- and fine-grained gradation. As the temperature of the added virgin aggregates increased, the ITS and moisture damage resistance of the mixture increased as well, but the difference was quite small. It was also observed that the mixture demonstrated better ITS and moisture damage resistance when using filler in material design. The relationships between curing time, moisture content, and strength of the mixture during curing were also investigated, and the variations of strength formation was summarised. The significance of the studied factors was finally analysed using a one-way analysis of variance based on the test results.

KEYWORDS:

• Foamed asphalt
• cold recycled mixture
• expansion ratio
• half-life
• indirect tensile strength
• tensile strength ratio

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [grant number 51878229]; Transportation Science and Technology Project of Jilin Province: [grant number 2017ZDGC-2-6, 2017ZDGC-2-2].