Abstract
Due to storage stability drawbacks of polymer-modified bitumen (PMB), this study investigated the storage stability and physicochemical performance of Styrene-Butadiene-Styrene (SBS) asphalt binders (herein PMB) modified with Silicone surface-treated nanosilica (SNS). Dosages 0% (control), 1.5%, 3% and 5% SNS powder were added to PMB to prepare modified binders. Hot storage, Viscosity, Multiple Stress Creep Recovery (MSCR), Scanning Electron Microscopy (SEM), Fluorescence Microscopy (FM), Linear Amplitude Sweep (LAS), Fourier Transform Infrared (FTIR), and Proton Nuclear Magnetic Resonance (1H-NMR) tests were conducted using modified binders. The study found that adding nanosilica powder to PMB improved storage stability, increased viscosity and complex modulus, and reduced rutting of binders. However, this bitumen modification was not beneficial to fatigue cracking. The performance improvement was because of the interaction between the polymer and nanosilica, creating a new polymer-nanosilica network which lowered the dynamics around the SNS particles, thereby reducing phase separation. Further, the Silicone Si–O–Si backbone bond present in SNS modified asphalt binder reduced temperature sensitivity thereby preventing thermal degradation at high storage temperature. Nanosilica modified binders presented well-dispersed nanosilica particles in the asphalt matrix. The modification mechanism was predominantly physical. Overall, the study concluded that nanosilica improves storage stability, rutting, and morphology of PMB binders.
Highlights
Bitumen or asphalt binder is utilized in the production of asphalt mixtures for road construction and industrial application
To accurately measure the fatigue cracking potential of SBS/nanosilica modified bitumen, the Linear Amplitude Sweep (LAS) test was employed using DHR-2 manufactured by TA Instruments (New Castle, DE, USA) in which the specimen is subjected to cyclic loading with increasing amplitudes
Functional groups are important in characterizing materials in the chemical process
Summary
Bitumen or asphalt binder (as it is referred to in North America) is utilized in the production of asphalt mixtures for road construction and industrial application. An example of an additive used for this purpose is Maleic anhydride (MAH); recent researchers, such as Su et al as cited in [20], found that the chemical modification of bitumen with polydimethylsiloxane (PDMS)—silicone oil could enhance the compatibility of modified asphalt binders and offer good storage stability. Previous studies have shown that the application of kaolinite in PMB achieves two main objectives namely: (1) enhancing PMB’s storage stability by reducing the difference in density between bitumen and its polymer-modifiers; (2) improving resistance to ageing of PMB with characteristics of the dispersed clay platelets [21]. Extant literature on nanosilica found that the additive improves anti-aging property, fatigue and rutting of modified binders and mixtures [24]; increases in strength of mixes, temperature stability and resistance to moisture susceptibility [28]; increases in complex shear modulus [29]; increases in viscosity [30]. It is a well-known fact that temperature is elevated up to 200 ◦C during hot storage and processing of bitumen, the bond energy in PDMS surface treated nanosilica is higher than C=C bonds due to the existence of Si–O–Si bonds, which can withstand thermal degradation at high temperatures
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