1. Introduction
Bitumen is a binding agent customarily used in flexible pavements that are usually built with hot mix asphalt (HMA). The increased road transport volume and construction-phase failures with environmental and external factors reduce asphalt pavements' useful life and increase the probability of permanent faults like rutting and moisture damage (Fareed et al. 2020, Haroon et al. 2022). More than 90% of global pavements are flexible because they are strong, last a long time, and can be repaired easily. Bitumen, a highly viscous material, is used as the asphalt's binder. It exemplifies the transition between the solid and liquid phases at different temperatures. Bitumen consumption has reached an all-time high of 700 million barrels per year. It is an organic compound composed of hydrocarbons and typically contains 1% carbon, 80% oxygen, and trace amounts of oxygen, sulfur, nitrogen, and other metals (Abdul Hassan et al. 2019).
A renewable resource, bitumen, is created through the distillation process. The depletion of natural resources has far-reaching consequences for both price increases and pollution. Bitumen has been altered with a wide variety of additives to combat the issue of waste management and boost the efficiency of traditional binders. Binders are expensive and harmful to the environment. However, using modified or substitute binders can reduce costs and help the environment (Ahmad et al. 2022). Various techniques were used to enhance the performance by modifying the binder, and the final product is designated synthetic bitumen. The partially synthetic bitumen reported by using various additives, i.e., polymers (Zhu et al. 2014), i.e., waste engine oil (Liu et al. 2018), modification of aggregate gradation (Aodah et al. 2012), Styrene Butadiene Styrene (SBS) (Yildirim 2007, Zhang and Hu 2013), crumb rubber (Xiao et al. 2009, Cetin 2013), PPA (Domingos and Faxina 2015), polyethylene (Mohanty 2013) and costly Nanomaterials (Fang et al. 2013, Fini et al. 2015).
Waste engine oil is a by-product of the automotive industry collected yearly from various automobiles. Zinc, lead, potassium, and magnesium are the most common contaminants, such as firewood. Due to the increase in population globally, every year, approximately 11 billion tons of waste are produced, indicating that each person produces more than one ton on average, and this number is increasing. According to estimates, waste generation will double by 2025 compared to 2000. Modern societies are based on using cars, which cannot operate without lubricants. The quantity of waste oil has increased with the population and vehicles. As the population increases, waste increases which causes landfill space and health problems (Counts 2023). Massive volumes of garbage, such as blast furnace slag, glass, steel slag, scrap tires, plastics, waste engine oil, building and demolition wastes, etc., are being dumped in landfills and stockpiles around the world, posing environmental and economic dangers (Abukhettala 2016).
Bitumen can be revitalized by adding used motor oil, making for an eco-friendlier product (Int et al. 2014). Although some of WEO is recycled, most ends up in the trash. Despite its changing production resources, the chemical composition of WEO matches that of bitumen. Bitumen treated with waste engine oil (WEO) was shown to have improved penetration and a lower softening point than unmodified bitumen (Abdul Hassan et al. 2019). Feng et al. (Feng et al. 2020) reported that a high concentration of WEO had unfavorable effects on the binder's properties. The injection of waste engine oil alters the elastic properties of bitumen, i.e., a decrease in complex modulus and a rise in phase angle. Liu et al. (Liu et al. 2018) reported that fatigue performance was improved by WEO, although bitumen loses some resistance to rutting. Liu et al. (Liu et al. 2019) concluded that the high rutting strength and performance are degraded, as reported by an analysis of the bitumen's rheological behavior. It was presented no proof of hydrophobic interactions between bitumen and WEO in their studies. More than that, they advocated a WEO adjustment of 4-8%. Jia et al. (Jia et al. 2014) concluded that the integration of WEO in binder reduces its excellent productivity, i.e., rutting resistance, as documented in the literature and through extensive evaluations of waste engine oil-modified bitumen. As the binder content was decreased, the mixture's fatigue resistance improved, and the concentration of organic aldehyde compounds in bitumen was raised through modification with used motor oil. The increased carbonyl groups in bitumen made it more vulnerable to oxidation. Furthermore, oil incorporation lowered stiffness at cold pressures, whereas high temperatures hampered the binder's elastic recovery and have been demonstrated.
Shoukat and Yoo (Shoukat and Yoo 2018) concluded that engine oil was found to have an improved influence on thermal cracking in dynamic evaluations of changed binders at the expense of decreased resistance to rutting. Filtered used engine oil decreased binder flexibility by 35% compared to virgin asphalt after only a few months of aging. Still, 2.5% oil lowered the Performance Grade (PG) of the top end by 0.3 °C. Overall, the performance of unprocessed waste motor oil was below that of both new and filtered crude oil. DeDene (DeDene 2011) reported that waste engine oil might make bitumen combined with Reclaimed Bituminous (RAB) less rigid and improve low-temperature characteristics. It is possible to reduce the hardness of asphalt roads by utilizing engine oil without reducing the roads' ability to withstand wet conditions.
Like Waste engine oil, the amount of automobile waste tires has also substantially increased worldwide in the past few years due to the evaluation of the automobile industries. Proper disposal or recycling of crumb rubber (CR) produced from automobile tires becomes very important for the environment. This massive waste material harms the earth's natural environment and pollutes the water, air, and soil. Eventually raises concern for global warming, economic crisis, energy preservation, and others. Using waste conserves road construction materials may minimize landfill space, reducing environmental impact. Therefore, scientists focus on innovating the disposal technique of these waste tires and waste engine oil as bitumen modifiers (Formela 2021). The examination of the automobile sector has helped to similar growth in the amount of waste tire produced around the world as has occurred with waste engine oil. Crumb rubber (CR), a by-product of tire recycling, must be disposed of or recycled correctly to prevent environmental damage (Lo Presti 2013). Burning one ton of used tires produces 450 kg of harmful gases & 270 kg of soot is kept out of the atmosphere. The use of CR as a modifier in asphalt is an excellent example of its application (Rumyantseva et al. 2020). The optimal preparation process parameters for rubber-modified asphalt include shear temperatures of 180 °C, shear times of 45 minutes, and shear speeds of 5000 rpm (Liu et al. 2015).
The dosage of crumb rubber also imparts the properties of the modified asphalt. S. Mashaan et al. (S.Mashaan et al. 2011) concluded that the increased crumb rubber content significantly improves elasticity and ductility. Shafabakhsh et al. (Shafabakhsh et al. 2014) reported that asphalt mixtures containing 10% waste rubber powder improved their performance at higher temperatures, reduced asphalt mixtures' sensitivity to temperature, and increased their resistance to rutting. Further, it also reduced the binder's production costs; rubberized asphalt mixtures had superior performance at high temperatures compared to the control specimens. Similarly, (Gohar et al. 2022) reported that adding 15% crumb rubber increases the stiffness, viscosity, and high softening point and improves the rutting resistance of conventional bitumen. The crumb rubber size also played a vital role in altering the asphalt properties.
Ibrahim et al. (Ibrahim et al. 2013) concluded that lowering the crumb rubber size improves asphaltic mixtures' rutting resistance, resilience, and fatigue cracking resistance. Brasileiro (Brasileiro et al. 2019) reported that crumb rubber has lower complex modulus values at low temperatures, minimizing the likelihood of cracking and enhancing pavement performance and endurance. Wang et al. (Wang, Liu, Apostolidis, et al. 2020) concluded that the swelling of rubber dramatically modifies its characteristics, making it softer and more viscous.
Huang (Huang 2008) concluded that the rutting resistance improved with increased viscosity and flexibility at high temperatures. In addition, the low temperature increased fatigue resistance because of a decrease in viscosity. The studies (Attia and Abdelrahman 2009, Wang et al. 2012, Moreno et al. 2013) concluded that CR improves pavement performance and mechanical responsiveness of changed binders in asphalt binders. The studies (Yu et al. 2014, 2017, Guo et al. 2017, Sienkiewicz et al. 2017) confirmed that utilization of CR is known to significantly enhance pavement qualities such as resistance against fatigue & rutting, improvement overall durability, and reduce maintenance costs. The studies (Navarro et al. 2004, Kim and Lee 2013) established that the encapsulation efficiency of rubber-modified bitumen is not a significant issue. It becomes a problem at higher temperatures. That becomes more pronounced as a considerable percentage of CR is integrated into the asphalt. The mechanical behavior of hot-mixed asphalt and the mechanical/chemical qualities of bitumen were improved by using the WEO-CR rejuvenator, which was also found to raise the overall performance of the mixture (HMA) (ELTWATİ et al. 2022).
Recently, bitumen has become highly technical, with modifiers like polymers, acids, and mineral fillers controlling its performance properties (Masson 2008). PPA is a reactive reagent comprised of phosphoric acid oligomers. PPA is compatible with asphalt, which considerably improves the performance of binders at high temperatures. The penetration index and viscosity values of bitumen have been enhanced due to increased asphaltenes content and decreased saturate and resins (Varanda et al. 2016). PPA might also be regarded as a viable alternative to polymers. Numerous researchers have investigated the chemical reaction between PPA and asphalt (Polacco et al. 2005). It was observed that the rheological properties of CRB-modified binder were enhanced by adding up to 2% PPA. PPA also enhanced the storage stability by raising the viscosity of CR-modified asphalt. High asphaltenes content increases resilience to rutting but decreases fatigue resistance (Qian et al. 2019). PPA improves the bitumen performance significantly. In addition, it was concluded that a bitumen addition of up to 1% substantially improves high-temperature performance while having a negligible effect on fatigue characteristics (Hao et al. 2019).
According to the literature mentioned above, the WEO as a modifier into the bitumen compromised the performance properties of the asphalt binder (Liu et al. 2018, 2019, Shoukat and Yoo 2018, Feng et al. 2020, Abbas et al. 2022). However, Crumb rubber (Huang 2008, Mashaan and Karim 2014, Yu et al. 2014, 2017, Guo et al. 2017, Sienkiewicz et al. 2017) and Polyphosphoric acid (Polacco et al. 2005, Varanda et al. 2016, Hao et al. 2019, Qian et al. 2019) improves the performance of asphalt binders and mixtures. In this regard, the performance of WEO-modified binders can be improved by using these two additives, i.e., CR and PPA. Many previous studies are available where CR and PPA have been used separately for improvement of WEO-modified bitumen, however, very limited work is available on the combined behavior of CR and PPA on WEO-modified bitumen. So, an indepth analysis was required to evaluate the combined effect of these two additices in WEO-modified bitumen. They were used to scrutinize their impact on the performance of the virgin binder. The main aim behind this study is to use maximum industrial waste (WEO) in the original binder and enhance the performance of WEO-modified biunder.
Figure 1.
Waste Engine Oil.
Figure 1.
Waste Engine Oil.
Figure 3.
Sample of Crumb Rubber.
Figure 3.
Sample of Crumb Rubber.
Figure 4.
Poly-phosphoric Acid (PPA).
Figure 4.
Poly-phosphoric Acid (PPA).
Figure 5.
Penetration and Softening Point of Virgin and WEO+CRB Modified Binder Results.
Figure 5.
Penetration and Softening Point of Virgin and WEO+CRB Modified Binder Results.
Figure 6.
Virgin and WEO + CRB Modified Binder Viscosity Results.
Figure 6.
Virgin and WEO + CRB Modified Binder Viscosity Results.
Figure 7.
Penetration and Softening Point of Virgin and PPA Modified Binder Results.
Figure 7.
Penetration and Softening Point of Virgin and PPA Modified Binder Results.
Figure 8.
Virgin and PPA Modified Binder Viscosity Results.
Figure 8.
Virgin and PPA Modified Binder Viscosity Results.
Figure 9.
FTIR Analysis of all the samples (WEO, CR, and PPA).
Figure 9.
FTIR Analysis of all the samples (WEO, CR, and PPA).
Figure 10.
The failing temperature of Virgin and WEO+CRB Modified Binder.
Figure 10.
The failing temperature of Virgin and WEO+CRB Modified Binder.
Figure 11.
The failing temperature of Virgin and PPA Modified Binder.
Figure 11.
The failing temperature of Virgin and PPA Modified Binder.
Figure 12.
Master Curve for Virgin and 5% WEO + CRB Modified Binder: (a) Phase Angle, (b) Rutting Resistance.
Figure 12.
Master Curve for Virgin and 5% WEO + CRB Modified Binder: (a) Phase Angle, (b) Rutting Resistance.
Figure 13.
Master Curve of for Virgin and 10% WEO + CRB Modified Binder: (a) Phase Angle, and (b) Rutting Resistance.
Figure 13.
Master Curve of for Virgin and 10% WEO + CRB Modified Binder: (a) Phase Angle, and (b) Rutting Resistance.
Figure 14.
Master Curve of for Virgin and 15% WEO + CRB Modified Binder: (a) Phase Angle, and (b) Rutting Resistance.
Figure 14.
Master Curve of for Virgin and 15% WEO + CRB Modified Binder: (a) Phase Angle, and (b) Rutting Resistance.
Figure 15.
Master Curve for the Virgin and WEO + CRB + PPA Modified Binder Master Curve of for Virgin (a) Phase Angle, and (b) Rutting Resistance.
Figure 15.
Master Curve for the Virgin and WEO + CRB + PPA Modified Binder Master Curve of for Virgin (a) Phase Angle, and (b) Rutting Resistance.
Figure 16.
POTS in Dry Condition of Virgin and WEO+CRB Modified Binder.
Figure 16.
POTS in Dry Condition of Virgin and WEO+CRB Modified Binder.
Figure 17.
POTS in Dry Condition of Virgin and WEO + CRB + PPA Modified Binder.
Figure 17.
POTS in Dry Condition of Virgin and WEO + CRB + PPA Modified Binder.
Figure 18.
POTS in Wet Condition of Virgin and WEO+CRB Modified Binder.
Figure 18.
POTS in Wet Condition of Virgin and WEO+CRB Modified Binder.
Figure 19.
POTS in Wet Condition of Virgin and PPA Modified Binder.
Figure 19.
POTS in Wet Condition of Virgin and PPA Modified Binder.
Table 1.
Mixing proportions.
Table 1.
Mixing proportions.
Sr. No |
Dosage |
1 |
Control blend (B) |
2 |
B+5% WEO+20% CB |
3 |
B+5% WEO+25% CB |
4 |
B+5% WEO+30% CB |
5 |
B+10% WEO+20% CB |
6 |
B+10% WEO+25% CB |
7 |
B+10% WEO+30% CB |
8 |
B+15% WEO+20% CB |
9 |
B+15% WEO+25% CB |
10 |
B+15% WEO+30% CB |
11 |
B+5% WEO+30% CB+0.6%PPA |
12 |
B+5% WEO+30% CB+1.2%PPA |
13 |
B+5% WEO+30% CB+1.8%PPA |
Table 1.
Statistical Analysis of Viscosity.
Table 1.
Statistical Analysis of Viscosity.
Statistical Analysis of Viscosity |
Additives |
N |
Subset at 95% confidence interval |
1 |
2 |
3 |
4 |
5 |
6 |
B+15%WEO+20%CR |
3 |
138.2 |
|
|
|
|
|
B+15%WEO+25%CR |
3 |
|
166.9 |
|
|
|
|
B+15%WEO+30%CR |
3 |
|
|
174.6 |
|
|
|
B+10%WEO+20%CR |
3 |
|
|
|
189.2 |
|
|
B+10%WEO+25%CR |
3 |
|
|
|
|
211.6 |
|
B+10%WEO+30%CR |
3 |
|
|
|
|
|
248.5 |
Sig. |
|
1.000 |
1.000 |
1.000 |
1.000 |
1.000 |
1.000 |
Additives |
N |
Subset at 95% confidence interval |
7 |
8 |
9 |
10 |
11 |
12 |
B+5%WEO+20%CR |
3 |
263 |
|
|
|
|
|
B+5%WEO+25%CR |
3 |
|
268.5 |
|
|
|
|
B+5%WEO+30%CR |
3 |
|
|
274.7 |
|
|
|
B+5% WEO+30 % CR+0.6%PPA |
3 |
|
|
|
284 |
|
|
B+5% WEO+30 % CR+1.2%PPA |
3 |
|
|
|
|
292 |
|
Virgin Binder |
3 |
|
|
|
|
294.7 |
|
B+5% WEO+30 % CR+1.8%PPA |
3 |
|
|
|
|
|
299 |
Sig. |
|
1.000 |
1.000 |
1.000 |
1.000 |
1.000 |
1.000 |
Table 2.
Statistical Analysis of Complex Modulus.
Table 2.
Statistical Analysis of Complex Modulus.
Statistical Analysis of Complex Modulus |
Additives |
N |
Subset at 95% confidence interval |
1 |
2 |
3 |
4 |
5 |
6 |
B+15%WEO+20%CR |
3 |
147.65 |
|
|
|
|
|
B+15%WEO+25%CR |
3 |
|
167.34 |
|
|
|
|
B+10%WEO+20%CR |
3 |
|
|
189.47 |
|
|
|
B+15%WEO+30%CR |
3 |
|
|
191.95 |
|
|
|
B+5%WEO+20%CR |
3 |
|
|
|
207.96 |
|
|
B+10%WEO+25%CR |
3 |
|
|
|
|
218.87 |
|
B+5%WEO+25%CR |
3 |
|
|
|
|
|
246.41 |
Sig. |
|
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
Additives |
N |
Subset at 95% confidence interval |
7 |
8 |
9 |
10 |
11 |
12 |
B+10%WEO+30%CR |
3 |
283.65 |
|
|
|
|
|
B+5%WEO+30%CR |
3 |
|
317.76 |
|
|
|
|
Virgin Binder |
3 |
|
|
353.72 |
|
|
|
B+5% WEO+30 % CR+0.6%PPA |
3 |
|
|
|
787.36 |
|
|
B+5% WEO+30 % CR+1.2%PPA |
3 |
|
|
|
|
1130.91 |
|
B+5% WEO+30 % CR+1.8%PPA |
3 |
|
|
|
|
|
2170.85 |
Sig. |
|
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
Table 3.
Statistical Analysis of Moisture Susceptibility.
Table 3.
Statistical Analysis of Moisture Susceptibility.
Statistical Analysis of Moisture Susceptibility |
Additives |
N |
Subset at 95% confidence interval |
1 |
2 |
3 |
4 |
5 |
B+15%WEO+20%CR |
3 |
1.3 |
|
|
|
|
B+10%WEO+20%CR |
3 |
|
1.57 |
|
|
|
B+15%WEO+25%CR |
3 |
|
|
1.775 |
|
|
B+10%WEO+25%CR |
3 |
|
|
|
2.180 |
|
B+15%WEO+30%CR |
3 |
|
|
|
2.305 |
2.305 |
B+5%WEO+20%CR |
3 |
|
|
|
|
2.423 |
Sig. |
|
1.000 |
1.000 |
1.000 |
1.000 |
1.000 |
Additives |
N |
Subset at 95% confidence interval |
6 |
7 |
8 |
9 |
B+10%WEO+30%CR |
3 |
2.64 |
|
|
|
B+5%WEO+25%CR |
3 |
2.83 |
|
|
|
B+5%WEO+30%CR |
3 |
|
3.305 |
|
|
B+5% WEO+30 % CR+0.6%PPA |
3 |
|
3.445 |
3.445 |
|
B+5% WEO+30 % CR+1.2%PPA |
3 |
|
|
3.622 |
3.620 |
Virgin Binder |
3 |
|
|
|
3.70 |
B+5% WEO+30 % CR+1.8%PPA |
3 |
|
|
|
3.80 |
Sig. |
|
0.079 |
0.444 |
0.144 |
0.119 |