Optimizing asphalt binder chemistry and rheology to control potential flexible pavement cracking

Drive for environmentally sustainable and economic construction practices had led to increase in the use of recycled materials in asphalt paving industry. However, recycled materials produce asphalt concrete mixes that are brittle and more vulnerable to cracking. Furthermore, factors like environmental aging and reduced quality of binders, further adds to binder embrittlement, thereby causing asphalt pavements to crack prematurely. To compensate, crude oil-based softening agents are often used as asphalt modification to improve asphalt concrete flexibility. Use of such oils may not be environment friendly and cost effective, hence, a variety of bio-based alternatives are now available. However, using bio-based alternatives affects binders’ chemical composition, rheological response, and affects their long-term aging, thereby making the use of bio-based alternatives a challenge. The primary objective of this doctoral dissertation is to systematically engineer a bio-based modifier to reduce long-term cracking in asphalt concrete pavement. The stated objective was achieved through implementing the following approach, (i) a long-term aging protocol for binders to distinguish their cracking potential was established, (ii) the effect of commonly available bio-based proprietary softening agents was evaluated for binder chemistry and rheology compatibility, (iii) the impact of bio-based oils for balanced asphalt concrete mixture performance was assessed, and finally (iv) synthesized a plant-based additive with improved crack resisting properties. The outcome of this dissertation suggests that the existing standard long-term aging (20hrs of pressure aging vessel (PAV)) method does not represent field conditions for pavement surface in Illinois. Rather field aging in Illinois corresponds to laboratory aging of 40hrs in PAV (2PAV) or greater, based on rheological and chemical binder characterization. The extent of 2PAV aging, however, was found to be limited to pavement surface and the impact of aging diminishes through pavement depth. The study showed that asphalt binder rheology was greatly influenced by the chemistry of bio-based modifiers and was significantly dependent on base asphalt characteristics. A series of rheological and chemical parameters, and their field validated acceptable thresholds were established. The impact of modified binder rheology on balanced asphalt concrete mixture performance was also quantified. The mixture performance correlated well with most of the modified binders. Ultimately, utilizing the outcome from the aforementioned findings, an epoxidized soybean oil (ESO) was chemically synthesized. The synthetic additive effectively reduced the modifier dosage by about 40% compared to ESO to achieve an acceptable cracking resistance. Asphalt binder with synthetic additive, produced from waste soybean oil was the next best alternative to virgin asphalt binder. Modification with the additives showed negative environmental impacts on asphalt binder production. Hence, life cycle assessment must be conducted while considering pavement performance.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Singhvi, Punit

Contributors dc:contributor

• Al-Qadi, Imad L
• Tutumluer, Erol
• Hajj, Ramez
• Bhasin, Amit
• Ozer, Hasan
• Sharma, Brajendra K

• Asphalt Chemistry
• Asphalt Rheology
• Asphalt Additives
• Long-term Aging
• Asphalt Field Aging
• Balanced Mix Design

Statement dc:rights

• Copyright 2022 Punit Singhvi

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/117549

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F117549