Improving the Reliability of Damage Characteristic Curves in the Simplified Viscoelastic Continuum Damage Model

Abstract

One of the major advantages of the cyclic fatigue test (AASHTO TP 107) is that the results can be used to calibrate the Simplified Viscoelastic Continuum Damage (S-VECD) model, which is used for mechanistic pavement performance predictions. The crux of the S-VECD model is the damage characteristic curve, which has been shown to be independent of mode of loading, loading history, and temperature. Consequently, a model can be fitted to the damage characteristic curve and used to predict the damage response for any given loading history of interest using limited test results. AASHTO TP 107 currently lacks a specific procedure for fitting a model to the damage characteristic curve and evaluating the repeatability of test replicates. In this study, a robust and practical method is proposed for fitting a power law model to the damage characteristic curve. The proposed fitting method was verified using cyclic fatigue test results of 19 mixtures sourced from the United States, Canada, and South Korea. In addition, a means to evaluate the specimen-to-specimen variability of damage characteristic curves using a shape factor is proposed. Thresholds for acceptable variability in the shape factor were derived using confidence interval analysis and verified through FlexPAVE™ pavement performance predictions. The findings of this study can be used to improve the reliability of the damage characteristic curves derived from cyclic fatigue tests for pavement performance predictions.

Comparison of Relative Structural Characterization Methods for Additive-Modified Asphalt Mixtures

“…For data analysis of the cyclic fatigue test results, a damage characteristic curve (Equation 2) was constructed by plotting the mixture pseudo-stiffness as a material integrity parameter ( C ) on the y-axis against the damage parameter ( S ) on the x-axis. The C- versus -S curve represents the fundamental damage characteristics of the mixture, which is independent of test temperature and loading frequency ( 21 , 22 ). In addition to the C- versus -S curve, the predicted N f at various strain levels ranging from 100 to 600 microstrain at 20°C was determined by applying the S-VECD model to the test data.…”

Use of Resampling Method to Construct Variance Index and Repeatability Limit of Damage Characteristic Curve

“…where E#(v,T)=storage modulus at a particular temperature and angular frequency (kPa or pounds per square inch [psi]); E#(v R )=storage modulus at a particular reduced angular frequency (kPa or psi); v R =reduced angular frequency (rad/s); max E#=maximum storage modulus; b, d, g=fitting coefficients; E 0 =maximum storage modulus value (kPa or psi); k, d, g, h, b, t E =fitting coefficients; and E# 2S2P1D =storage modulus from the 2S2P1D model. The damage characteristic curve, one of the key material functions, is represented by the power law model in this study based on the results of Lee et al (19).…”

Application of Miller yield criterion to develop a unified fatigue law of asphalt mixture for different loading modes

“…The VECD method uses the damage characteristic curve (C–S curve) to reflect the damage evolution of the asphalt mixture 29 . Kim et al proved that the C–S curve of asphalt mixture obtained in the monotonous tension test is consistent with that obtained from the cyclic fatigue loading test 30,31 . Besides, the C–S curve is also unaffected by loading level.…”

“…29 Kim et al proved that the C-S curve of asphalt mixture obtained in the monotonous tension test is consistent with that obtained from the cyclic fatigue loading test. 30,31 Besides, the C-S curve is also unaffected by loading level. As a result, some research recommended using the VECD method to reveal the unified fatigue law of the mixture.…”