Document Type

Thesis - Open Access

Award Date

2018

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Rouzbeh Ghabchi

Keywords

asphalt binder, asphalt mix, binder bond strength, moisture-induced damage, strain energy, tensile strength

Abstract

The current thesis presents the findings of a study conducted on asphalt mixes to evaluate their moisture-induced damage potential through testing of the plant produced asphalt mixes in South Dakota using local aggregates and commonly used asphalt binders. The moisture-induced damage potentials of the asphalt mixes were evaluated by conducting tensile strength ratio (TSR) and modified Semicircular Bend (SCB) tests. The effect of moisture on asphalt binder-aggregate adhesion was evaluated by conducting binder bond strength (BBS) test on binder-aggregate systems. The asphalt mixes tested in this study included a hot mix asphalt (HMA) containing hydrated lime (1% by the weight of aggregates), asphalt mix containing an amine-based warm mix asphalt (WMA) additive (0.5% by the weight of mix), and asphalt mix containing reclaimed asphalt pavement (RAP) (20% by the weight of aggregates). Asphalt binder-aggregate adhesion evaluation plan comprised of testing sixteen types of asphalt binder blends, namely PG 64-34, PG 64-22, PG 58-28, and PG 70-28, blended with simulated RAP binder, an amine-based antistripping agent (ASA), and an amine-based WMA additive. The BBS tests were conducted on combinations of the binder blends with three types of aggregates, namely quartzite, granite-I, and granite-II. A total of forty eight combinations of asphalt binderaggregate systems were tested. Tensile strength ratio obtained from TSR test, critical strain energy release rate, and energy release ratio (ERR) obtained from modified SCB test, and pull-off strength obtained from BBS test for unconditioned and moistureconditioned samples were used to evaluate the moisture-induced damage. The indirect tension (IDT) test results were used to perform a fracture energy analysis of the TSR samples in dry and moisture-condidtioned states to explore the feasibility of applying this method for evaluating the moisture-induced damage utlizing parameters such as toughness index, toughness index ratio (TIR), fatigue index and fatigue index ratio (FIR). The result showed that the asphalt mixes tested in this study met the minimum TSR requirement set by the Superpave® mix design method. The critical strain energy release rate of HMA for both dry and moisture-conditioned samples were found to be lower than the range recommended by the ASTM D8044-16 standard (ASTM, 2016). For the asphalt mix containing RAP and the asphalt mix containing WMA additive, the critical strain energy release rate values of dry and moisture-conditioned samples were found to meet the minimum values recommended by the ASTM D8044-16 standard (ASTM, 2016). The ERR and FIR values calculated for all mixes were found to be greater than one, indicating no decrease in their resistance to cracking after moisture-conditioning. The TIR values calculated for the mixes were found to be less than one for HMA mixes but greater than one for the mix containing RAP, and the mix containing WMA additive. The pull-off strength ratio (PSR) obtained from BBS tests showed that PG 58-28 binder containing 20% RAP by the weight of the binder with granite-I had a higher moisture-induced damage potential compared to other asphalt binder-aggregate systems tested in the study. The PG 64-34 binder containing 0.5% ASA with granite-I, and PG 58-28 binder containing 0.5% WMA additive with granite-II were found to have higher PSR than the other asphalt binder-aggregate combinations tested in the current study. The findings of this study are expected to help engineers and the asphalt industry select asphalt binders and aggregates which are more compatible in order to minimize moistureinduced damage in asphalt mixes.

Library of Congress Subject Headings

Asphalt concrete -- Moisture.
Asphalt -- South Dakota -- Testing.
Aggregates (Building materials) -- Testing.
Binders (Materials) -- Testing.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

152

Publisher

South Dakota State University

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Rights Statement

In Copyright