Experimental study of asphaltic concrete dynamic properties as an impervious core in embankment dams

The seismic behaviour of asphaltic concrete used as an impervious core in embankment dams was investigated.To evaluate the specimen’s dynamic behaviour, an extensive series of monotonic and cyclic triaxial tests were carried out. Bitumen content between 5.5% and 7.0% with 0.5% increments were selected for the tests. Isotropic and anisotropic initial stress conditions with different principal stress ratio were also considered in this study. Thousands of cycles were imposed on some of the specimens, to study their fatigue behaviour due to seismic loading. A small degradation could be seen but no cracking was observed on the cutting surfaces. All tests were carried out at a constant temperature of 22 °C simulating a constant temperature inside a dam in tropical climate regions. Shear modulus in the compression region (Gc) and tension region (Ge) are presented for different Bitumen content, confining stress, stress ratio (Kc) and loading type. The damping ratio was also presented for different loading states. A regression equation was also derived for determining cyclic and maximum shear modulus (Gmax) of the asphaltic concrete for different Bitumen content as a function of confining stress which can be used in numerical studies.

► Asphaltic concrete core retains its stability even after a moderate earthquake.
► The higher Bitumen content, the more is the amount of failure axial stress.
► The more the Bitumen content and confining stress, the less is the Secant modulus.
► Increasing the values of Kc, will increase modules both in tension and compression.
► The least and the most damping is observed at 6% and 7% Bitumen respectively.