Abstract
Severe Canadian winter conditions and growing traffic volumes are vital factors resulting in a reduction of the service life of flexible pavements. Researchers and engineers strived to develop several additives to develop balanced asphalt mixers capable of resisting distresses that caused deterioration of flexible pavements in Canada. In this study, a critical literature review regarding the use of geopolymers and their application in construction materials is provided. Moreover, an experimental matrix of laboratory testing was conducted to study the rheological and microstructural properties of the PG 58-28 asphalt binder, with different percentages (0%, 3%, 6%, and 9%) of geopolymer. The effect of geopolymer-curing time on rheological properties was investigated. Rotational viscometer, dynamic shear rheometer (DSR), and environmental scanning electron microscopy (ESEM) imaging devices were used to compare the performance of control binder with a binder with different percentages of geopolymers. Results indicated that the increase in the geopolymer content and the curing time affect the rheological behavior of the asphalt binder by increasing its viscosity, complex shear modulus, and failure temperature. Samples with higher geopolymer percentage exhibited better performance in terms of rutting resistance. Moreover, an increase in the failure temperature of modified asphalt binder with 9% geopolymer is recorded as 8.58%, 14.2%, and 15.2% for curing times of 2, 7, and 14 days, respectively, compared with virgin asphalt. Furthermore, the nanoparticles appear to be well dispersed in the binder, and increasing the percentage of the geopolymer does not seem to affect the microstructure of the binder. Overall research conclusion is that geopolymer application resulted in a potential enhancement of some of the properties of the asphalt binder.
Highlights
Modified asphalt binder could be used to reduce pavement distresses such as rutting and cracking
Geopolymer was the combination of fly ash and the alkali activator. e alkali activator was sodium silicate solution (Na2SiO3) and sodium hydroxide (NaOH) pallet diluted in water to produce 8 Molar (8 M) NaOH solution
Geopolymer could be used as a sustainable and greener alternative to other asphalt modifiers due to its low carbon dioxide footprint and effective by-products/waste better recycling capacity. is paper presented a laboratory study to investigate the effects of geopolymer content on the rheological and microstructure properties of asphalt binder. e following conclusions have been drawn: (i) Geopolymer additives had a notable impact on the rheological behavior of asphalt binder
Summary
Modified asphalt binder could be used to reduce pavement distresses such as rutting and cracking. In the past two decades, growth in the use of polymer-modified asphalt binders in pavement-engineering applications was noticed. Scholars investigated the use of waste materials to improve the performance of asphalt binders. Sodium hydroxide and sodium silicate were used as an alkaline activator, and fly ash was used as a pozzolanic material. E use of by-product materials such as fly ash enhances the sustainability of pavement mixtures and reduces the emission of CO2. Xu and van Deventer [26] noted that the addition of sodium hydroxide solution to the sodium silicate solution as the alkaline liquid improved the reaction with fly ash. The microstructure of base and modified asphalt binder was investigated using the environmental scanning electron microscope (ESEM)
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