# Stone Matrix Asphalt with Fischer–Tropsch Wax and Recycled Rubber: A Multi-Scale Evaluation of Mechanical and Functional Performance

## TL;DR

This study shows that combining Fischer–Tropsch wax and recycled rubber in asphalt improves road durability, safety, and sustainability.

## Contribution

The study introduces a hybrid modification system using FTW and RP to enhance SMA11 performance across multiple scales.

## Key findings

- 4% FTW balances rutting resistance and aging durability in PMB.
- 15% RP reduces braking distance by 13% after accelerated polishing.
- RP dosage affects performance: 5% for moisture resistance, 10% for noise reduction, 15% for mechanical durability.

## Abstract

What are the main findings?
The 4% FTW achieves an optimal balance between rutting resistance and aging durability in PMB.The FTW–RP synergy reduces the thermal cracking failure temperature by up to 8.0 °C.The 4% FTW enables a 20 °C reduction in production temperature for SMA11 mixtures.The 15% RP promotes self-texturing and reduces braking distance by 13% after accelerated polishing.RP dosage governs performance outcomes: 5% for moisture resistance, 10% for noise reduction, 15% for mechanical durability.

The 4% FTW achieves an optimal balance between rutting resistance and aging durability in PMB.

The FTW–RP synergy reduces the thermal cracking failure temperature by up to 8.0 °C.

The 4% FTW enables a 20 °C reduction in production temperature for SMA11 mixtures.

The 15% RP promotes self-texturing and reduces braking distance by 13% after accelerated polishing.

RP dosage governs performance outcomes: 5% for moisture resistance, 10% for noise reduction, 15% for mechanical durability.

What are the implications of the main findings?
Hybrid modification supports sustainable road construction through waste tire reuse and literature-supported emission reductions associated with lower production temperatures.A multi-scale approach links binder rheology directly to long-term pavement functionality.The results enable targeted tailoring of asphalt properties to meet specific urban or heavy-duty pavement requirements.Self-texturing rubberized surfaces significantly enhance long-term road safety.

Hybrid modification supports sustainable road construction through waste tire reuse and literature-supported emission reductions associated with lower production temperatures.

A multi-scale approach links binder rheology directly to long-term pavement functionality.

The results enable targeted tailoring of asphalt properties to meet specific urban or heavy-duty pavement requirements.

Self-texturing rubberized surfaces significantly enhance long-term road safety.

This study investigates the synergistic use of Fischer–Tropsch wax (FTW) and recycled rubber powder (RP) as dual modifiers in stone mastic asphalt (SMA11) to improve its mechanical and functional performance. Rheological analysis demonstrated that an FTW content of 4% achieves the optimal balance of high-temperature rutting resistance, aging resistance, and workability, with a binder viscosity of 1.6 Pa·s at 135 °C. When incorporated into SMA11 mixtures at 15%, RP yielded the best overall mechanical performance, including a reduction in rut depth to 1.22 mm and a 25% decrease in wheel tracking slope (WTS). The 15% RP mixtures also exhibited superior long-term skid resistance (μm = 0.329 after 180,000 polishing cycles, corresponding to a 13% reduction in braking distance) and enhanced thermal cracking resistance (failure temperature improved by 8.0 °C to −32.7 °C). An RP content of 5% maximized moisture resistance (ITSR = 100%), while 10% RP produced the highest mid-frequency sound absorption coefficient (α = 0.050). The hybrid modification system enables a 20 °C reduction in production temperature, consistent with published data on wax-based warm-mix technologies, and is associated with reduced energy consumption and lower emissions. The approach simultaneously supports sustainable pavement design through the high-value reuse of waste tire rubber.