The Effect of the Kaolinitic Clay and Asphaltenes on the Rheological Properties of Trinidad Lake Asphalt and Trinidad Petroleum Bitumen-Clay Composites

Abstract

Trinidad Lake Asphalt (TLA) is a source of superior quality asphalt and is often specified as a mandatory ingredient for paving in high-demand applications. The TLA resource is limited and expensive and the ability to synthetically convert refinery petroleum bitumen such as Trinidad Petroleum Bitumen (TPB) into a TLA-like material would be a very profitable and more sustainable approach. The objective of this paper is to determine whether kaolinitic clay and asphaltenes when blended with TPB can improve its rheological properties and produce a TLA-like material. Studies were conducted using dynamic (oscillatory) shear rheology (DSR) to measure changes on the rheological properties of complex modulus, degree of stiffness, G*, and phase angle, degree of elasticity, δ, of blends. Although the addition of kaolinite to TPB resulted in changes to the rheological properties (G* and δ) of the blends to values closer in magnitude to TLA, the properties of TLA were not achieved. Removal of the inorganic kaolinitic component from TLA resulted in a significant decrease in the complex modulus and an increase in the phase angle to values close to TPB (δ equal to 89.6 for TLA and δ equal to 89.1), demonstrating the key role played by the kaolinitic clay in the rheological properties of TLA. The addition of Valencia clay and asphaltenes to TPB clearly showed that in tandem, they play a significant rheological role in the TPB blends as it was possible to produce blends with similar or even better rheological properties compared to pure TLA. The TPB blend containing 30% Valencia clay and 30% asphaltenes exhibited a G* higher than that of TLA and a δ that was marginally less than that of TLA. This study also demonstrated the ability to create customized TPB blends to suit special applications by manipulating the kaolinitic clay and asphaltenes content.