Analytical modelling of complex stiffness modulus tests in direct tension-compression on asphalt concrete and nonlinearity effect due to strain amplitude

A new analytical model is designed to reproduce the complex modulus of asphalt concrete in cyclic dynamic tests. Instead of multiplying rheological elements with fixed parameters, only two elements with variable parameters are connected in parallel: the stiffness component R-E related to the strain and the viscosity component S-eta related to the strain rate. They compose the VENoL (NOnLinear ViscoElastic) model. Their variations as a function of pulsation are calibrated with the Carreau- Yasuda model at a reference temperature and strain amplitude. The conversion from one temperature to another is done using the Time-Temperature Superposition Principle defined by its shift factor a(T). For the conversion from one strain amplitude to another (nonlinearity), the Time-Amplitude SemiSuperposition Principle is newly created, defined by two shift factors aA and b(A). The model is calibrated with experimental data from the literature based on direct tension-compression tests. The results obtained corroborate the experiments accurately.

Automated summary

A new analytical model is developed to reproduce the complex modulus of asphalt concrete in cyclic dynamic tests, using two elements with variable parameters and calibrated with experimental data.