Modelling the Stability of Asphalt Concrete with Fuzzy Logic and Statistical Methods for Various Freezing and Thawing Cycles

The stability of asphalt concrete under the effects of freezing and thawing was studied experimentally, and the experimental test results were modelled using fuzzy logic and statistical methods. The stability was investigated experimentally using the Marshall and ultrasound methods. Asphalt core samples 10 cm in diameter were alternately frozen (–20°C for 16 hr) and thawed (16°C for 8 hr) for 5, 10, 15, 20, 25, and 30 cycles to simulate daily winter conditions. The stability of asphalt concrete at the laboratory environment temperature of 17°C was used as a reference. The results showed that the stability of asphalt core samples exposed to freezing and thawing increased, and this increase varied between 22.7% and 19.2% for 5- and 30-day cycles, respectively. By using Fuzzy Logic and statistical methods, prediction models were constituted based on freezing-thawing cycle, bitumen ratio, saturated unit volume weight, volume of voids, air dry unit volume weight to predict the Stability of asphalt concrete which could not be determined with experimental. The experimental results, the fuzzy logic model, and the statistical results showed good correlations. For the stability of asphalt core samples, the correlation coefficient was R² = 0.88 for the fuzzy logic model and R² = 1.0 for the statistical method. Based on the results of this study, it is clear that both the fuzzy logic and statistical methods can be used to model the stability of asphalt concrete under various freezing and thawing conditions.