Influence of modifiers, anti-stripping agents and fillers on rheological and mechanical performance of asphalt mastic and asphalt mixture

Feroz, Shahrul Ibney (2023) Influence of modifiers, anti-stripping agents and fillers on rheological and mechanical performance of asphalt mastic and asphalt mixture. Masters thesis, Memorial University of Newfoundland.

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Abstract

Filler, a fine powder used in asphalt mixture, plays a dual role as an inert filler to fill gaps between mineral aggregates and an active filler to mix with asphalt binder to generate a high-consistency asphalt mastic. Many studies have been conducted to develop a rheological parameter that can assess the deformation and creep characteristics of asphalt binders and asphalt mastics. This study investigated the creep recovery performance of asphalt binder and mastic. Mastic is prone to distresses in flexible pavement that worsen with aging, including cracking and moisture-induced damage. The study highlights the importance of fillers combined with modifiers and anti-stripping agents and compares the rheological and mechanical performance of aged asphalt mastics and asphalt mixtures. Multiple Stress Creep Recovery (MSCR) was utilized to understand the rutting performance of aged asphalt binder and mastic. The performance of asphalt mastic with different filler-binder ratios or proportions of different fillers combined with SBS or Gilsonite containing Zycotherm or AD-Here was utilized. Rolling Thin-Film Oven (RTFO), protocol was applied to simulate asphalt production time aging. The study utilized various parameters such as non-recoverable creep compliance, stress sensitivity analysis, percent recovery analysis, and polymer modification curve to compare the performance of the binders and mastics. Scanning Electron Microscope (SEM), and X-ray fluorescence spectroscopy test (XRF), were carried out to shed light on the physical and chemical properties of the fillers. The Marshall stability and flow test, Indirect Tensile Strength (ITS), and Retained Marshall Stability tests were performed to elucidate the mixtures’ mechanical performance and moisture susceptibility. Finally, ANOVA analysis was conducted at the binder, mastic, and mixture level to determine the factors influencing the rutting performance of asphalt mastics and the mechanical performance of asphalt mixtures. According to the experimental data from binder level analysis, 0.1% Zycotherm as an anti-stripping agent modified with 4% SBS satisfied binder performance requirements. Mastic and mixture level analysis suggested that HL0.5 modified with 4% SBS containing 0.1% Zycotherm was predominant when only active or inert filler is used and 10% HL and 70% LS containing 4% SBS, and 0.1% Zycotherm was predominant when a combination of active and inert filler was used. These mastics satisfied all the requirements for rutting, moisture damage, and cracking resistance. However, the combination of active and inert filler (10% HL + 70% LS) performed slightly better than the mastic prepared with only active filler (HL). The findings highlight the importance of fillers, modifiers and anti-stripping agents in enhancing the rutting and moisture-induced damage resistance of asphalt mixtures and the usefulness of the MSCR test in evaluating the performance of the asphalt mastic.

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