Experimental and Numerical Studies of Viscoelastic Behavior of Bituminous Mixture with a High Rate of Reclaimed Asphalt Pavement, Dune Sand and Lime

Road construction is now a priority in the economic and social development policy of a country. The increased need to improve the infrastructure system and to counter the deficit in certain quarry gravels and non-renewable resources while saving increasingly expensive road investments, makes recourse to the use of abundant and inexpensive materials in order to reduce the use of non-renewable natural materials. The objective of this research is to predict the viscoelastic behavior of asphalt mixtures incorporating high Reclaimed Asphalt Pavement (RAP) content, allowing to reduce the consumption of new aggregates and bituminous binders, and other additives such as dune sand and lime. A new formula containing 3,7% of 35/50 penetration grade virgin bitumen, 40% of Reclaimed Asphalt, 10% of dune sand, and 1% of hydrate lime was tested and compared to the conventional formula containing 5,3% of the same virgin bitumen. To evaluate the impact of dune sand and lime addition on the mechanical behavior of bituminous mixtures containing high rates of RAP, complex modulus tests were conducted on the studied mixtures, at different temperatures and frequencies, using a two-point bending device that was developed at the National School of Engineers of Tunis. Their viscoelastic properties were determined using a Generalized Maxwell model which was calibrated by 2S2P1D model. The paper describes a three-dimensional Finite Element (FE) model developed using ABAQUS software, that is used to simulate 2-point bending tests on trapezoidal samples of the studied mixtures to determine their complex modulus and accurately predict their mechanical behavior under traffic loading at ranges of temperatures and frequencies that are not experimentally accessible. To validate the FE model, determined viscoelastic properties have then been introduced into through the Prony series and its outputs were validated by experimental measurements. Both experimental and numerical results show that the use of RAP, dune sand and lime greatly improves the rigidity of the mix at high temperatures. A suggested continuation of this work would be an investigation of the rutting resistance.