Effects of an Amine Anti-Stripping Agent on Moisture Susceptibility of Sasobit and Aspha-Min Mixes by Surface Free Energy Analysis
Effects of an Amine Anti-Stripping Agent on Moisture Susceptibility of Sasobit and Aspha-Min Mixes by Surface Free Energy Analysis

Author: Aravinda Buddhala

Publisher:

Published: 2012

Total Pages: 9

ISBN-13:

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Warm mix asphalt (WMA) is a fairly recent technology developed primarily to address issues such as high vapor emissions and high energy costs associated with the traditional hot mix asphalt (HMA) paving. Although the WMA is becoming a popular paving technology through field and laboratory evaluations, many researchers and transportation personnel are concerned about its moisture resistance. The present study analyzes the free energy of adhesion or wetting ability between eight different aggregates and an asphalt binder modified with varying dosages of two warm mix additives, namely Sasobit and Aspha-Min. Sasobit showed a maximum of 20.9 % and an average of 12.8 % increase in the free energy of adhesion in dry condition. The adhesion in the presence of moisture, referred to as free energy of reduction, was also evaluated to understand the moisture susceptibility of the WMA. The lower the free energy of reduction, the lower the asphalt binder's tendency to de-bond from aggregates in the presence of moisture. A maximum of 20.5 % and an average of 13.2 % decrease in the free energy of reduction were observed for asphalt binder with 3 % Sasobit. However, Aspha-Min did not exhibit any significant effect on any of the surface properties. One amine-based anti-stripping agent, AD-here HP Plus, is studied to evaluate its effect on adhesion and moisture susceptibility of the WMA. While its performance as an anti-stripping agent was good on the plain asphalt binder, AD-here HP Plus did not improve the adhesion of the selected binder modified with WMA additives either in dry or wet condition. The free energy of adhesion in wet and dry conditions showed either detrimental or no effect with selected aggregates, suggesting a negative or no influence of AD-here HP Plus on the WMA additive-modified binder.

Quantify Antitrip Additives in Asphalt Binders and Mixes
Quantify Antitrip Additives in Asphalt Binders and Mixes

Author:

Publisher:

Published: 2004

Total Pages:

ISBN-13:

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In this study, litmus and colorimetric tests were developed to quantify the contents of amine-based antistrip additives in asphalt binders and mixes. In addition, the effect of prolonged heating on antistrip additive content was evaluated for both asphalt binders and mixes. Results of this study indicate that both litmus and colorimetric tests are capable of detecting and quantifying amine-based antistrip additives in asphalt binders and mixes. Also, both test methods were able to validate the antistrip additive contents in field samples with known additive contents. When subjected to prolonged heating periods, the antistrip additive content decreased substantially for both asphalt binders and mixes. For asphalt binders, no antistrip additive content was detectable after 24 to 48 hours of extended heating; for mixes, the measured antistrip additive content approached non-detectable level after 6 to 12 hours of extended heating. Tensile Strength Ratio test was conducted in this research to evaluate the effect of prolonged heating on the asphalt-aggregate bond strength of hot mix asphalt (HMA) containing liquid antistrip additives. Improvement of moisture sensitivity by use of amine-based antistrip additive was observed to be lost to a great extent after prolonged heating. It shows that the remaining part of antistrip additive after prolonged heating has reduced effect on adhesion between asphalt and aggregate. The volatilization and⁄or chemical change that occur during the heating process of amine-based antistrip additive affect the improvement of asphalt-aggregate adhesion and ultimately the moisture susceptibility of mixes.