Using Cantabro Test Results to Predict Asphalt Mixtures’ Cracking Resistance: A Practical Decision-Support Tool During Production

The Virginia Department of Transportation (VDOT) has adopted the balanced mix design (BMD) framework for selected surface mixtures. The BMD framework provides a performance-oriented approach and offers the potential to overcome limitations commonly associated with traditional mix design methods that rely solely on volumetric requirements. Nonetheless, challenges remain with production-level BMD tests, often limiting producer’s ability to take timely corrective actions to address mixture composition issues that could affect cracking performance. To address this challenge, this study aimed to identify and quantify the impact of volumetric and gradation parameters on asphalt mixtures’ cracking performance. Over 140 mixture compositions were used to establish and verify cracking tolerance index ( CT Index ) predictive equations. In addition to volumetrics and gradation, Cantabro mass loss (CML) data were used to help improve CT Index predictions. Pairwise correlation and variance inflation factor analyses were used to remove collinear factors. A forward stepwise multiple linear regression method was used to identify significant factors and develop predictive equations under a tiered approach (Tier 1 through Tier 3) to reflect the different testing frequencies at which volumetrics and gradation data are obtained during production. Results showed that asphalt content, percent passing sieve #200, absorbed asphalt content, and voids in the mineral aggregate are key CT Index predictors. The CML results further improved model accuracy. A risk assessment demonstrated that the predictive equation incorporating CML can serve as a practical decision-support tool, enabling practitioners to identify potential mix design issues and determine when additional testing is needed during production.