Experimental characterisation and modified Burgers modelling of viscoelastic creep behaviour in a fluid mastic asphalt mixture (FMA)

The Fluid Mastic Asphalt mixture (FMA) is a novel hot-mix asphalt mixture with lower air void content. To investigate creep performance of FMA, the creep tests were conducted on FMA at three asphalt binder contents, under various temperatures and stress levels. The Burgers and modified Burgers were applied to fit the first and second stages of creep compliance curve of FMA. Using the Least Absolute Shrinkage and Selection Operator (LASSO) regression method, a mathematical model was proposed to predict creep compliance. The creep deformation mechanism of FMA was illustrated by analyzing creep activation energy. The results showed that the correlation coefficient ( R2) of traditional Burgers model was approximately 0.96, whereas that of modified Burgers model reached 1.0, indicating that modified Burgers model more accurately captured viscoelastic behavior of FMA. The proposed mathematical model can effectively predict creep compliance of FMA. The presented results indicate that creep mechanism of FMA is dominated by diffusion creep, governed by the dislocation mechanism of aggregate interface. The creep activation energies of FMA with asphalt binder contents of 6%, 7%, and 8% were 20.31 kJ, 18.27 kJ, and 16.37 kJ, respectively. These obtained values indicate that FMA exhibits greater stability and resistance to rutting.