Estimating tensile strength ratio of asphalt mixtures using Surface Free Energy (SFE) and Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR)

Moisture damage often leads to pavement failure, particularly as pavements age. The widely adopted AASHTO T283 test evaluates asphalt mixtures’ susceptibility to moisture damage but has shortcomings, time-consuming procedures, and lack of representation of realistic aging effects. Given the adoption of AASHTO T283 by state agencies, this study aimed to establish correlations with reliable and practical tests, especially Surface Free Energy (SFE)’s work of cohesion (Wc) and Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) tests’ carbonyl and sulfoxide indices, to estimate AASHTO T283′s Tensile Strength Ratio (TSR%). Three asphalt binders (PG 52–34, PG 64–22, and PG 76–22) were assessed at oxidation levels (original, short-term, and long-term). Analysis of Variance (ANOVA) and linear regression analysis were conducted to assess the relationship between SFE and FTIR-ATR with TSR%. Results showed PG 52–34 mixtures had the highest TSR%, while PG 76–22 mixtures had the lowest, decreasing with higher oxidation. PG 52–34 had higher Wc values than PG 76–22, reducing with higher oxidation. FTIR-ATR measured higher carbonyl and sulfoxide index values for PG 52–34 and lower values for PG 76–22. ANOVA and linear regression analysis highlighted correlations between TSR%, SFE, and FTIR-ATR, with the combined effects of Wc, carbonyl, and sulfoxide indices showing the strongest relationship. The findings demonstrate that SFE and FTIR-ATR measurements showed potential in predicted TSR% for the asphalt mixtures. Particularly, predicted TSR% values differed the highest from actual TSR% for PG 52–34 without aging and at short-term aging but achieved accurate predictions with small absolute differences under long-term aging conditions.