# Micromechanical Finite Element Model Investigation of Cracking Behavior and Construction-Related Deficiencies in Asphalt Mixtures

## TL;DR

This study uses detailed computer models to better understand how cracks form in asphalt mixtures and how construction flaws affect their strength.

## Contribution

A micromechanical finite element model with high predictive accuracy was developed to assess construction-related deficiencies in asphalt mixtures.

## Key findings

- Micromechanical models showed higher accuracy (R2 = 0.86–0.98) compared to homogenized models (R2 = 0.66–0.77).
- Higher air voids (4% to 10%) reduced peak load by up to 35% and increased stress concentrations by up to 40%.
- Discontinuous gradation and aggregate segregation caused premature cracking and complex fracture paths.

## Abstract

This study investigated the fracture behavior of asphalt mixtures under indirect tensile loading by comparing the performance of homogenized and micromechanical finite element (FEMs) models based on the cohesive zone model (CZM). Five asphalt mixture types were tested experimentally, and both models were calibrated and validated using load–displacement curves from indirect tensile tests (IDTs). The micromechanical model, incorporating random aggregate generation and three-phase material definition, exhibited significantly higher predictive accuracy (R2 = 0.86–0.98) than the homogenized model (R2 = 0.66–0.77). The validated micromechanical model was further applied to quantify the impact of construction-related deficiencies—namely, increased air voids, non-continuous gradation, and aggregate segregation. The simulation results showed that higher void content (from 4% to 10%) reduced peak load by up to 35% and increased localized stress concentrations by up to 40%. Discontinuous gradation and uneven aggregate distribution also led to premature crack initiation and more complex fracture paths. These findings demonstrated the value of micromechanical modeling for evaluating sensitivity to mix design and compaction quality, providing a foundation for performance-based asphalt mixture optimization and durability improvement.