Based on the Superpave™ Standard Specifications for testing asphalt binders, the under-listed test procedures were conducted on both the control and the four nano-clay modified asphalt binders:
a) Rotational viscosity test (RV) - Standard Method for Viscosity Determinations of Unfilled Asphalts Using the Thermosel Apparatus, ASTM 4402).
b) Dynamic shear rheometer test (DSR) - Rheological Properties of Asphalt Binder Using Dynamic Shear Rheometer AASHTO TP5
c) Rolling thin film test (RTFO) - Standard Method of Test for Effect of Heat and Air on a Moving Film of Asphalt, AASHTO T240
d) Direct tensile test (DTT) - Method for Determining the Fracture Properties of Asphalt Binder in Direct Tension, AASHTO TP3
At temperatures of 80, 100, 130, 135, 150 and 175°C, the Brookfield Rotational Viscosity equipment was used to determine the viscous behavior of the control binder and the four types of prepared nanoclay-modified PG 64-28 binders. The speed for running the RV test was 100 rpm. In terms of the low and mid-temperature rheological properties, the DSR equipment was used at temperatures 13°C to 70°C and loading frequencies ranging from 0.01Hz to 25 Hz. The critical parameters sought here were the complex shear modulus (G*) and phase angle (5) which are used to determine the rutting and fatigue cracking resistance behavior of the asphalt binder systems (Asphalt Institute 2003, Asphalt Institute). To determine the low temperature cracking resistance performance of the neat and nanoclay-modified asphalt binder system, the modified Superpave™ direct tensile test (DTT) procedure was employed. The DTT evaluated the low temperature ultimate tensile strain/stress at -18°C on both the neat and modified asphalt binders.
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