Rheological behavior of bitumen mixed with Trinidad lake asphalt

Trinidad lake asphalt (TLA) has been utilized as a modifier to blend with conventional petroleum bitumen for road and bridge applications where highly stable surfacings are required. The aim of this work was to evaluate the effect of TLA on rheological properties of Trinidad lake modified asphalt (TLMA). The critical content of TLA in the modified blend by weight was determined as the interaction of mineral particles occurred. Test results showed that TLA stiffened asphalts, but the degree of stiffening varied significantly with the TLA concentration levels. An increase in complex modulus (G*) and elastic response (δ) resulting from the introduction of TLA to asphalt binders had the potential benefit of improving resistance to rutting. In addition, zero shear viscosities (ZSVs) obtained from the Cross model were equal to the low shear viscosities (LSVs) at a frequency of 0.05 Hz, while the ZSVs from the Carreau model were close to the LSVs at 0.1 Hz. Steady state viscosities (SSVs), having the lowest values, approximately equaled the LSVs at 0.5 Hz. The concentration of TLA was recommended to be in the range of 20–33% by the weight of naturally modified asphalt according to the SSV stiffening effect.