A Procedure to Quantify Organic Antistrip Additives in Asphalt Binders and Mixes
A Procedure to Quantify Organic Antistrip Additives in Asphalt Binders and Mixes

Author: C. Chen

Publisher:

Published: 2006

Total Pages: 6

ISBN-13:

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Stripping is a phenomenon of loss of bond or adhesion between the asphalt binder and the aggregate in asphalt mixes. Stripping frequently results from the presence of water, and most agencies require the use of antistrip additive to control moisture damage. However, there is no simple and quick method for detecting the presence and the amount or percentage of organic antistrip additive in asphalt binders or mixes. This paper presents a procedure based on solid-state spectrophotometry to detect qualitatively and quantitatively the presence of amine-based antistrip additive in asphalt binders and mixes. The developed procedure gives results that are quantifiable and reproducible with low coefficients of variation.

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.

Laboratory Evaluation of Anti-strip Additives in Hot Mix Asphalt
Laboratory Evaluation of Anti-strip Additives in Hot Mix Asphalt

Author: Bradley J. Putnam

Publisher:

Published: 2006

Total Pages: 178

ISBN-13:

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The use of hydrated lime or other liquid anti stripping agents (ASA) is the most common method to improve the moisture susceptibility of asphalt mixes. However, most laboratory test conditions used to evaluate the moisture susceptibility of the mixes are only for a short duration of time. This might not be a good representation of the field conditions (i.e., several months or years of service). Thus, a study to evaluate the effects of conditioning the mixes for longer durations was initiated. Also, another problem with the use of the liquid anti stripping agents is their heat storage stability. This report addresses these two issues, by preparing and testing mixtures made with fresh binder for indirect tensile strength after conditioning the samples for 1, 7, 28, 90 and 180 days, and samples prepared from binder stored for three days at 160° C after conditioning them for 1, 28 and 90 days. The results of this study indicated that hydrated lime and the liquid anti stripping agents were equally effective for the mixes used in this research when conditioned beyond one day. In the case of samples prepared from stored binder, there was no significant difference in the effectiveness of hydrated lime and the liquid anti stripping agents even after conditioning for one day. Though it was observed that none of the ASA treatments performed better than others in the case of samples prepared with stored binder, it was also observed that almost all mixes gave significantly similar wet ITS and TSR values as samples prepared from fresh binder.

Quantitative Determination of Asphalt Antistripping Additive
Quantitative Determination of Asphalt Antistripping Additive

Author: G. W. Maupin

Publisher:

Published: 2004

Total Pages: 24

ISBN-13:

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A small device (StripScan) has been developed by InstroTech, Inc., that uses litmus paper and a spectrophotometer to analyze vapors from hot liquid asphalt binders and mixtures to determine the percentage of antistripping additive present. Approximately 60 five-point additive content-color index count regressions were performed on binders and mixtures to determine how well the StripScan device measured additive content. The regressions basically fit the quadratic format that is used by the manufacturer in the recommended calibration process. The regressions were best when the litmus color index count was calculated by subtracting the initial count of the blank strip from the final count after exposure for the mixtures. Changes to the instrument software and testing temperature were necessary as the investigation progressed to accommodate different grades of binders. After the planned testing was completed, some retesting of the binders was performed using modified equipment and procedures. The changes appeared to improve the consistency of the results; therefore, the author believes that additive content in binders can be determined within +0.2 percent 95 percent of the time using the modified equipment and procedures. Test results for mixtures were less accurate than for binders; however, if the vapor trap is modified as described, the accuracy for mixtures should be improved substantially. Since the test can be performed quickly, multiple tests on a sample are possible. This would increase the confidence of the test results. Additional research and development is recommended and necessary before the device can be used for quality assurance testing. An accuracy of +0.1 percent is a worthy goal.

Special Mixture Design Considerations and Methods for Warm Mix Asphalt
Special Mixture Design Considerations and Methods for Warm Mix Asphalt

Author:

Publisher: Transportation Research Board

Published: 2012

Total Pages: 53

ISBN-13: 0309213738

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TRB's National Cooperative Highway Research Program (NCHRP) Report 714: Special Mixture Design Considerations and Methods for Warm-Mix Asphalt: A Supplement to NCHRP Report 673: A Manual for Design of Hot-Mix Asphalt with Commentary presents special mixture design considerations and methods used with warm-mix asphalt. NCHRP Report 714 is a supplement to NCHRP Report 673: A Manual for Design of Hot-Mix Asphalt. All references to chapters in NCHRP Report 714 refer to the corresponding chapters in NCHRP Report 673.

A Literature Review of Liquid Antistripping and Tests for Measuring Stripping
A Literature Review of Liquid Antistripping and Tests for Measuring Stripping

Author: Christine W. Curtis

Publisher:

Published: 1990

Total Pages: 30

ISBN-13:

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The purpose of this literature review is to search the literature in the area of chemical and mineral agents used to promote adhesion of asphalt-aggregate mixes. In addition, tests performed to measure the effectiveness of these agents were reviewed. The information gained through this literature search and review provides background information for the research being performed in the SHRP A-003B contract. This literature search was performed using on-line chemical abstracts for documents in the time period of 1967 to present.