Mechanical Behavior of Bitumen: In the Context of Bitumen Coated Piles

Sammanfattning

Bitumen has long been used in geotechnical applications as a coating on piles to modifythe interaction between the pile surface and the surrounding soil. Relative groundsettlements induce negative skin friction, increasing axial loads and reducing structuralcapacity. A well-established method to mitigate this effect is to apply a thin layer ofbitumen. However, despite bitumen’s long-standing use in practice, the mechanismsgoverning the behavior of bitumen and its effectiveness in reducing pile–soil interactionremain insufficiently understood.In this thesis, the fundamental mechanical behavior of bitumen is investigated to establisha basis for the numerical evaluation of adhesion strength in bitumen-coated piledesign. A literature review is combined with the implementation of suitable constitutivematerial models, which are subsequently calibrated using available experimental data.The results suggest significantly lower adhesion values than those commonly adoptedin design. However, the essential viscoelastic behavior of bitumen can be adequatelydescribed within the calibrated range of the model. Nevertheless, due to limited experimentaldata for realistic loading conditions, significant extrapolation in both strainmagnitude and strain rate was required, increasing uncertainty in the predicted response.Consequently, further experimental studies are required to characterize bitumen’s behaviorwhen subjected to the large deformations and low strain rates observed in practice.This will enable more reliable calibration of the material model for practical designapplications.