Rheological, Chemical, and Water Resistance Properties of Asphalt Binders Modified with Selected Warm Mix Additives

Warm mix asphalt (WMA) can reduce the mixing and compaction temperatures by 16 to 55 degrees C compared to hot mix asphalt (HMA). These considerable reductions in production temperatures result in lower fuel demand, a better workplace environment, and lesser emissions of greenhouse gases, etc. This study evaluated three Arkansas Department of Transportation (ARDOT)-approved performance grade (PG) binders: PG 64-22, PG 70-22, and PG 76-22 modified by four WMA additives: Sasobit, Advera, Evotherm, and Rediset. Penetration, rotational viscometer (RV), dynamic shear rheometer (DSR), Fourier transform infrared spectroscopy (FTIR), surface free energy (SFE), Texas boiling, and acid number (pH) tests were performed on these samples. The RV test results showed a slight reduction (up to 5 oC) in mixing and compaction temperatures for Sasobit, Evotherm, and Rediset modified binders. Binder samples modified by Sasobit and Advera showed improved rut resistance among all the samples. Both Evotherm and Rediset modification resulted in higher surface free energy compared to their corresponding unmodified binders. FTIR test results showed that Advera introduced sulfoxide (S=O) and hydroxyl (-OH) groups into base binders. Texas boiling test results showed that asphalt retention was high (>80%) for both Evotherm and Rediset modified samples. Acid number test results showed that both Advera and Rediset increased pH values of binder samples compared to their corresponding unmodified samples. These results will help the agencies and contractors choose the right WMA technology for asphalt paving projects.