Sun et al 2016 investigated WCO as a modifier to conventional asphalt in

Sun et al 2016 investigated wco as a modifier to

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Sun et al. (2016) investigated WCO as a modifier to conventional asphalt in concentrations of 2, 4, 6, and 8%. During this study, viscosity decreased while increasing WCO in the blend because of the dilution effect, which makes it compatible with the above- mentioned bio-oils [16]. Additionally, Zargar et al. (2012) investigated the effect of using the WCO as a rejuvenating agent to aged binders in a concentration of 1 5% [27]. The authors reported that 3 4% of WCO could rejuvenate an aged binder 40/50 (pen-grade) to be comparable to 80/100 with respect to physical and rheological characteristics. Fast pyrolysis bio-oils (e.g., oakwood, switchgrass, and cornstover) have different characteristics compared to WCO. Fast pyrolysis bio-oils have the potential to be asphalt replacers to a great extent, as they are asphalt-like materials (viscoelastic, temperature- susceptible, comparable viscosity, etc.); however, WCO is a pure liquid at room temperature, which could be added to asphalt binder in very limited concentrations. 3.4. Summary of Bio-Oil/Bio-Binder Viscosity It was clear that bio-oil, in general, had the potential to provide a partial or entire replacement to conventional asphalt (petroleum-based binder) in terms of viscosity investigation regardless of the source of bio-oil. All investigated fast-pyrolysis bio-oils provided a similar tendency to petroleum-based binders. However, they could provide comparable viscosities at relatively lower temperatures, which is desirable in the construction (mixing and compaction) process for lower energy consumed, hence lower construction expenses. On the other hand, WCO
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Ahmed Hemida, Magdy Abdelrahman 401 [email protected] provided much lower viscosity, which is a pure liquid at room temperature. For instance, WCO viscosity was measured by Sun et al. (2014), and it resulted in 146.3 cP at room temperature [16]. 4. VISCOELASTICITY OF BIO-OILS/BIO-BINDERS AT ELEVATED TEMPERATURES 4.1. Waste Wood Peralta et al. (2012) investigated the rheological properties of bio-oil as bio-binder (i.e., 100% asphalt replacer) produced from the fast pyrolysis of oakwood. The critical (pass/fail) temperature was investigated to evaluate the rutting resistance of four kinds of bio-binders containing bio-oil with either cryogenic (cryo) tire rubber, or ambient (amb) tire rubber. These four bio- binders were coded A, B, D, and E (“A” and “D” contain 90% bio -oil and 10% cryo and amb, respectively, and “B” and “E” contain 85% bio -oil and 15% cryo and amb, respectively) [8]. Figure 4 shows the critical temperature of conventional asphalt PG64-16 and the above-mentioned four bio-binders. They were investigated original (before heat treatment), heat-treated, and bio-binder residue (bio-binder residue after extracting tire rubber). The untreated bio- oil had a grade of 47.87℃, and the heat -treated bio-oil had a slightly higher grade (49.20℃). However, the tire rubber significantly enhanced its grade. This enhancement indicated a better rutting resistance performance, which was attributed to an overall improvement in the net elastic and stiffness properties. However, 15% of rubber
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