Optimization and characterization of asphalts modified with isocyanate modifier

With the increase of traffic volumes, higher axle loads and harsh climate conditions, the paving industry relies on the use of polymer modified asphalts. With the progress of polymer science and technology, new polymer modified asphalt technologies have emerged. Among the most innovative modification technologies belong the use of B2last, a commercial product of BASF. Unlike other polymer modifiers, B2last is characterized as reactive mono- and oligomeric aromatic diisocyanate. Besides the formation of covalent bonds with polar species present in asphalt, the conversion of B2last into polymer could also be anticipated. In this thesis, a soft conventional asphalt was modified by B2last. The development of modification technology and the effect of B2last on the properties of asphalt was investigated by Superpave binder specification and Fourier-transform infrared spectroscopy (FTIR). The initial Superpave results suggested that B2last had a significant effect on maximum service temperature and resistance to the effects of short-term aging. This could be attributed to the reactive nature of the modification, as the additional oxygen and high temperatures could have led to further conversion of B2last and formation of heavier molecules. Due to the poor performance of B2last modified asphalt in the Multiple Stress Creep and Recovery experiment, the formulations of ternary modified asphalts containing B2last and vulcanized SBS were studied via the Design of Experiments. A positive interaction between the materials was found at high service temperatures, where the thermo-oxidative sensitivity of crosslinked SBS was generally mitigated by the presence of B2last. Lastly, the effect of B2last in paving mixes was evaluated and compared to the performance of hot mix asphalts containing asphalts prepared by a variety of modification technologies. The formulations included asphalt modified with B2last, vulcanized SBS, straight run asphalt with low Pen grade, catalytically oxidized asphalt, and optimized ternary blends containing SBS and B2last. While the samples modified with only vulcanized SBS had a superior performance in several tests, some of the ternary blends showed similar properties while using reduced amounts of total modifiers by weight, leading to the potential formulation of superior performing asphalt mixes with a reduced total content of polymer modifiers.

Name thesis:degree_name

Master of Science (MSc)

Discipline thesis:degree_discipline

Engineering – Civil

Grantor dc:publisher.institution

Graduate Studies

Year dc:date.issued

2024

Author dc:creator

• Tellez Vega, Esteban Felipe

Advisor dc:contributor.advisor

• Jasso, Martin

Committee members dc:contributor.committeemember

• Sleep, Sylvia
• Khoshnazar, Rahil

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

en

DOI

https://doi.org/10.11575/PRISM/43323

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/118481