# Mesoscale Steady-State Dynamics Modeling and Parametric Analysis of the Viscoelastic Response of Asphalt-Bonded Calcareous Sand

## TL;DR

This paper introduces a new mesoscale model to predict the mechanical behavior of asphalt-bonded calcareous sand, enabling efficient parametric analysis and design optimization.

## Contribution

The novel contribution is a mesoscale framework combining random particle algorithms and steady-state dynamics for efficient parametric analysis of asphalt-bonded calcareous sand.

## Key findings

- The SSD approach enables rapid calculation of dynamic modulus across a wide frequency range for large RVEs.
- Variations in maximum aggregate size have negligible impact on dynamic modulus under constant volume fraction.
- An optimal ITZ thickness of ~75 µm balances interfacial reinforcement and binder cohesion.

## Abstract

Due to the complex mesostructure of calcareous sand, accurately predicting the mechanical response of Asphalt-Bonded Calcareous Sand (ABCS) is extremely challenging. This study pioneers the development of a mesoscale model for ABCS that explicitly incorporates the Interfacial Transition Zone (ITZ) via a random particle algorithm. To overcome the efficiency bottlenecks of traditional time-domain integration, this study establishes a mesoscale framework coupling a random polygonal aggregate algorithm with direct Steady-State Dynamics (SSD) analysis. A major advantage of this framework is its capacity for large-scale parametric sensitivity analysis; herein, 920 independent mesoscale models were generated and rapidly solved across the broadband frequency domain. The framework was rigorously validated, demonstrating high predictive accuracy for both the baseline calibration and an independent 12% asphalt content mixture (baseline R2 = 0.99, MAPE = 6.94%; independent validation R2 = 0.96, MAPE = 9.73%). Notably, the SSD approach completes calculations (10−3 to 103 Hz) for 10 massive 300 mm RVEs in just 6.5 min. Leveraging this high-throughput capability, the extensive parametric analysis reveals that variations in maximum aggregate size negligibly impact the dynamic modulus under a constant volume fraction. Conversely, an optimal Interfacial Transition Zone (ITZ) thickness of ~75 µm was identified, representing a physical equilibrium between interfacial reinforcement and bulk binder cohesion. Furthermore, an analytical RVE size criterion of 1.7–5.3 times the maximum aggregate size is proposed to satisfy a 5% engineering error tolerance, providing a highly efficient numerical tool for the virtual mix design of reef pavements.