# Investigating the Impact of Surfactant-Based Warm-Mix Additives on the Performance of Recycled Asphalt Mixtures

## TL;DR

This study examines how surfactant-based warm-mix additives affect the performance of recycled asphalt mixtures, finding both benefits and trade-offs in terms of deformation resistance and water stability.

## Contribution

The study introduces a self-developed plant-oil-based rejuvenator and evaluates surfactant-based warm-mix additives in recycled asphalt mixtures.

## Key findings

- Warm-mix additives reduce penetration and softening point but increase ductility of recycled asphalt.
- WMRA mixtures showed lower complex modulus and rutting factor, indicating reduced deformation resistance.
- Warm-mix rejuvenator improved water stability compared to regular rejuvenators in soaked Marshall tests.

## Abstract

This investigation aimed to assess the influence of warm-mix additives on the performance characteristics of recycled asphalt mixtures. Pressure-aging vessels were employed to simulate the aging of asphalt binders. Warm-mix recycled asphalt (WMRA) and mixtures were prepared by incorporating self-developed plant-oil-based rejuvenators and surfactant-based warm-mix additives. The rheological properties of asphalt were tested by a dynamic shear rheometer (DSR). Furthermore, the pavement performance of the asphalt mixture was evaluated by a rutting test, beam bending test, Marshall stability test, and freeze–thaw splitting test. The experimental results demonstrated that the addition of warm-mix additives reduces the penetration and softening point of recycled asphalt while enhancing its ductility. Performance improvement was quantitatively evaluated using a recovery index. The complex modulus and rutting factor of the WMRA were found to be lower than those of recycled asphalt, indicating a decrease in the asphalt’s resistance to deformation owing to the surfactant. Both the hot-mix and warm-mix recycled asphalt mixtures met the specified requirements for various performance indicators. The warm-mix rejuvenator outperformed the regular rejuvenator in evaluating water stability using the soaked Marshall residual stability method, whereas the evaluation based on the freeze–thaw splitting strength ratio demonstrated the opposite trend.