- Email: [email protected]
Crack resistance of hot mix asphalt containing different percentages of reclaimed asphalt pavement and glass fiber
Construction and Building Materials 230 (2020) 117015
Contents lists available at ScienceDirect
Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Crack resistance of hot mix asphalt containing different percentages of reclaimed asphalt pavement and glass fiber Hassan Ziari a, M.R.M. Aliha b,⇑, Ali Moniri c, Yasha Saghafi c a
Asphalt and Bitumen Research Center (ABRC), School of Civil Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran, Iran Welding and Joining Research Center, School of Industrial Engineering, Iran University of Science and Technology, Narmak, 16846-13114 Tehran, Iran c School of Civil Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran, Iran b
h i g h l i g h t s The cracking resistance of asphalt mixtures declines by adding RAP at 0 °C and 15 °C. Glass fibers are beneficial for enhancing the cracking resistance of asphalt mixtures. The positive effect of glass fibers can compensate for the adverse impact of RAP material. The use of RAP material improves cracking performance at 15 °C.
a r t i c l e
i n f o
Article history: Received 12 April 2019 Received in revised form 20 August 2019 Accepted 15 September 2019
Keywords: Cracking behavior SCB fracture test 100% RAP mixtures Reclaimed asphalt pavement Recycled asphalt
a b s t r a c t Escalating the price of asphalt binder and environmental issues have led to an increasing desire to use high amounts of reclaimed asphalt pavement (RAP) material in asphalt mixtures. However, increasing the RAP content may have negative effects on some characteristics of asphalt mixtures, such as cracking resistance. Therefore, finding an approach to compensate for the negative impacts of RAP material may be considered as a solution to raise the RAP content in asphalt mixtures. Fibers are known as one of the modifiers that are added directly to the mixtures and enhance the cracking resistance of asphaltic materials. Therefore, in this study, the cracking behavior of asphalt mixtures containing different percentages of RAP material in combination with glass fibers was investigated using the semi-circular bending (SCB) fracture tests at temperatures of 15, 0 and 15 °C. The results showed that using up to 0.12% glass fiber leads to a significant enhancement in resistance of all mixtures against crack initiation and propagation. Moreover, it was found that the negative impact of RAP material on the crack resistance of asphalt mixtures is reversible to a great extent using 0.12% glass fiber, and 100% RAP mixtures are applicable without any significant reduction in crack resistance. Ó 2019 Elsevier Ltd. All rights reserved.
1. Introduction The huge use of aggregates as a raw material in asphalt pavements has depleted the rock and aggregate resources [1]. Furthermore, the high price of asphalt binder has caused financial problems in asphalt production. Reusing of reclaimed asphalt pavement (RAP) in new asphalt mixtures can be an approach to reduce the usage of valuable aggregates and expensive binder [2–5]. Less aggregate extraction, transportation, and processing operations can also be mentioned as other advantages of recycling RAP material [6]. Despite aforementioned benefits, there are some problems associated with the use of high contents of RAP material ⇑ Corresponding author. E-mail address: [email protected] (M.R.M. Aliha). https://doi.org/10.1016/j.conbuildmat.2019.117015 0950-0618/Ó 2019 Elsevier Ltd. All rights reserved.
in asphalt mixtures such as a reduction in cracking resistance and poor low-temperature performance due to the brittleness of its aged binder [7–9]. For this reason, most agencies do not allow high contents of RAP material in newly produces asphalt mixtures [10,11]. Shu et al in 2007 investigated the crack resistance of asphalt mixtures containing up to 30% of RAP material using the J-integral principles [9]. They showed that the cracking resistance of asphalt mixtures declines by increasing the amount of RAP material. The fracture resistance of asphalt mixtures containing different percentages of RAP and recycled asphalt shingles (RAS) material was evaluated using the fracture energy approach on semi-circular bending (SCB) specimens at temperatures of 12 °C and 25 °C [12]. It was found that the fracture energy of asphalt mixtures at both temperatures significantly declined when 40% of RAP material was used. Zhou et al (2017) investigated the frac-
2
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
ture energy of asphalt mixtures with up to 50% of RAP material at intermediate temperatures of 15 °C and 25 °C [13]. The results approved the previous researches, and the cracking resistance of asphalt mixtures declined by raising the RAP content. Therefore, improving the low-temperature performance and cracking resistance of the RAP mixtures can provide the possibility to increase the RAP content in asphalt mixtures. There have been some attempts to compensate for the weakness of recycled mixtures against cracking. Different types of rejuvenators and modifiers are introduced to enhance the cracking performance of recycled asphalt mixtures [14–18]. Zaumanis et al. (2014) compared the performance of six different rejuvenators in modifying the RAP aged binder. It was indicated that the performance grade of aged binder can be completely restored using waste vegetable oils, waste vegetable grease and organic oils [19]. However, in another study, Zaumanis and Mallick showed that the fracture work of rejuvenated 100% RAP mixtures is significantly lower than that of the virgin mixture [20]. Kodippily et al. (2016) used styrene–butadiene–styrene (SBS) as virgin binder modifier in 30% RAP mixtures to make up the adverse impacts of RAP material. It was indicated that the lost resistance against reflective cracking is almost recoverable when SBS modified virgin binder is used [21]. Zhou et al. investigated two kinds of rejuvenators and styrene-butadiene rubber (SBR) latex modified virgin binder in warm mix asphalt (WMA) containing 50% RAP. They showed that the 50% RAP mixtures modified with rejuvenator and SBR latex performed better than the conventional HMA mixtures in terms of low temperature and fatigue performance [22]. It can be seen in previous researches that using polymer modified virgin binders in combination with rejuvenators can restore the performance of recycled asphalt mixtures. However, as the content of virgin binder decreases by increasing the RAP content, using polymer modified binders cannot be efficient for mixtures containing high contents of RAP material and specifically, 100% RAP mixtures. Moreover, polymer modified binders are not applicable when the hot in-place recycling method is employed. Therefore, finding an alternative modifier which is added directly to the mixture can be a more proper solution to compensate for the negative impact of the aged binder of RAP material on middle and lowtemperature performance of asphalt mixture. Fibers are a kind of modifier that is added directly to the mixture and improve the resistance of asphalt mixtures against cracking and fatigue [23– 29]. Glass fibers have shown a good potential to improve the rutting and cracking performance of asphalt mixtures [30–32]. Improved healing capability and higher rutting, moisture and fatigue resistance are also reported as benefits of glass fibers in asphalt mixtures [33]. Fatigue and cracking are of the most prevalent asphalt layer defects especially in areas with cold and harsh weather [34–36]. Initiation and propagation of cracks through the asphalt overlays are related to traffic loading, thermal stresses and temperature gradient [37–39]. Fracture mechanics is one of the techniques for evaluating the crack resistance of asphalt mixtures [40–44]. The semicircular bending (SCB) fracture test is known as a popular method for evaluating fracture performance of asphalt mixtures due to the convenience in sample preparation and its reliable results [36,38,44–47]. Cracking is more probable at low temperatures due to the brittleness of the binders and mixtures [38]. Since the use of RAP material increases the brittleness of asphalt mixtures, the cracking behavior of the mixtures containing high contents of RAP material is questionable. The main objective of this research is to evaluate the effect of glass fiber reinforcement on cracking resistance of recycled asphalt mixtures and the optimum fiber content in asphalt mixtures containing different percentages of RAP material. For this purpose, asphalt mixtures containing 25%, 50%, 75% and 100% RAP and
Cyclogen as rejuvenator were reinforced with different percentages of glass fiber (0.06%, 0.12%, and 0.18% by weight of total mixture), and evaluated in terms of cracking performance using the J integral procedure at temperatures of 15, 0 and 15 °C. The results were compared to the results of mixtures without RAP and fiber as a control mixture.
2. Materials 2.1. Binder The binder used in this research was a PG 64-16 grade asphalt binder provided from Pasargad oil company. Table 1 shows the physical properties of this binder.
2.2. Aggregates Limestone aggregates were used as raw material for producing the asphalt mixtures. The physical characteristics of the aggregates were tested, and the results are listed in Table 2.
2.3. Fiber Glass fibers, which are categorized as High-performance ballistic fibers, are used in this study as asphalt mixture modifier. These fibers are manufactured of recycled crushed glasses via pultrusion process as explained by Tam and Bhatnagar [48]. An example image of glass fiber used in this study is shown in Fig. 1. The properties of fibers used in this study are summarized in Table 3.
2.4. RAP material and rejuvenator The RAP material used in this study was obtained from the milling operation of a freeway in Tehran. The binder content and gradation of the RAP material were determined after extracting its binder according to ASTM D2172 [49]. This procedure was carried out once for fine aggregates (passing sieve No 8) and once for the retained material on 2.36, 4.75, 12.5 and 19 mm sieves. The results, which were then used for gradation of the total mixture, are listed in Table 4. Cyclogen, which is categorized as aromatic extracts [6,50], was used in this study as the rejuvenator. The physical properties of this rejuvenator are provided in Table 5. The aged binder of RAP material was recovered using the rotary evaporator according to ASTM D5404-17 [51]. The optimum amount of rejuvenator was calculated as 6% of aged binder regarding the performance grade of the rejuvenated binder for both rejuvenators. For this purpose, the binder of the RAP material was recovered using ASTM D5404. Then different percentages of rejuvenator were added to the recovered binder until the lower grade reached the lower grade of the virgin binder [35,52]. In this research, the PG grade of the recovered RAP binder was PG 82-10, which was upgraded to PG 70-16 by adding the rejuvenator.
3. Methodology This research consists of three main stages. At first, the optimum binder content (OBC) of each mixture was determined using the Marshall procedure based on AASHTO T245 [53]. Afterward, cylindrical specimens with a diameter of 150 mm containing different percentages of RAP (0, 25, 50, 75 and 100%) and glass fiber (0, 0.06%, 0.12%, and 0.18% by weight of total mixture) were produced and cut to SCB specimens. Then, the SCB fracture tests at 15, 0 and 15 °C were conducted to evaluate the cracking resistance of the mixtures.
Table 1 Physical properties of asphalt binder. Test
Unit
Standard
PG 64-16
Viscosity test at 135 °C (cSt) Penetration test (0.1 mm) Ductility test (cm) Softening point (°C) Flash point (°C) Specific gravity
centistokes 0.1 mm cm °C °C g/cm3
ASTM ASTM ASTM ASTM ASTM ASTM
364 66 100 49 290 1.018
D113 D5 D113 D36 D92 D70
3
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
venator was added directly to the RAP material and mixed together. The rejuvenated RAP material was then mixed with virgin aggregates and fibers, which were gradually added to the mix. Afterward, the virgin binder was added to the mixture and intermixed. The total mixtures were then placed in compaction temperature for two hours [6]. The prepared mixtures were then placed in superpave gyratory compactor (SGC) with 150 mm diameter mold and compacted until reaching the target air void of 7% using the theoretical maximum specific gravity and the desirable bulk specific gravity [35,55–57]. The compacted cylindrical specimens were cut to SCB specimens according to ASTM D 8044 [58]. Artificial notches with 0.3 mm width and lengths of 25 mm, 32 mm and 38 mm were then created in the middle of SCB specimens. The schematic details of preparing SCB samples from cylindrical specimens are shown in Fig. 2.
Table 2 Physical properties of the limestone aggregates used in this research. Test
Unit
Coarse aggregate specific gravity Fine aggregate specific gravity Los Angeles abrasion value (LAV) Sodium sulfate soundness (SS) Sand equivalent (SE) Flakiness
3
g/cm g/cm3 % % % %
Standard
Result
ASTM C127 ASTM C128 ASTM C131 ASTM C88 ASTM T176 BS-812
2.57 2.54 22.2 2.7 65 16.63
3.2. SCB fracture tests For conducting the SCB fracture tests, at first, all SCB samples were placed at target temperature at least for 8 h. A tensioncompression test machine with a fixture with a support distance of 127 mm was then used to apply monotonic load with a rate of 0.5 mm/min as shown in Fig. 3. All tests were conducted under mode I condition on SCB specimens with three notch lengths at temperatures of 15, 0 and 15 °C in accordance with ASTM D8044. Four replicates were conducted for each notch depth, and the fracture energy before and after the peak load and critical value of J integral (Jc) were determined for each mixture.
Fig. 1. Glass fiber used in this research.
Table 3 Mechanical and physical properties of the glass fiber used in this study. Feature
Unit
Glass fiber
Color Specific gravity Length Diameter Tensile strength Melting point Water absorption
– g/cm3 mm mm MPa °C %
White 1.18 12 <0.13 >1000 800–900 0
3.2.1. Crack resistance criteria The mode I fracture toughness (KIC) is defined as the fracture resistance criterion of asphalt mixtures at minus temperatures, at which the elastic behavior is dominant in asphalt mixture, and the linear elastic fracture conditions are met [40,59]. This parameter was calculated using Eq. (1) for the specimens having 25 mm notch depth tested at 15 °C.
3.1. Mix design and sample preparation Table 5 The physical characteristics of the rejuvenator used in this study.
The first stage of the mix design was aggregate gradation. All mixtures were graded based on the mid-curve of the recommendation of ASTM D3515 [54] with a nominal maximum aggregate size of 19 mm. The information in Table 4 was used to keep the aggregate gradations of each mixture similar to each other. After the Marshall procedure had been carried out, the optimum amounts of virgin binder required for the mixtures containing 0%, 25%, 50%, 75% and 100% RAP material was determined as 5.4%, 3.93%, 2.55%, 1.23% and 0.33% by weight of total mixture respectively. For preparing the specimens, virgin aggregates and RAP material was kept at 175 °C for 16 and 2 h respectively. Next, the reju-
Rejuvenator property
Rejuvenator
Base Physical state at room temperature Color Odor Water solubility Viscosity at 135 °C (s) Flash point (°C) Specific gravity (g/cm3)
Oil Liquid Black No No 10 218 0.973
Table 4 Binder content and gradation of sieved RAP material. Sieve size (mm)
19 12.5 4.75 2.36 0.3 0.075 Binder content (%)
Passing percentage RAP
RAP retained on 19 mm sieve
RAP retained on 12.5 mm sieve
RAP retained on 4.75 mm sieve
RAP retained on 2.36 mm sieve
RAP Passing through 2.36 mm sieve
100 98.2 69.3 47.2 15.8 6 5.4
4.8 4.8 4.8 4.8 3.7 2.9 5.2
100 6.2 6.2 6.2 4 3.5 5.2
100 100 7.1 7.1 4.6 2.7 5.4
100 100 100 9.7 5.3 3.1 5.6
100 100 100 100 26.1 7.2 6
4
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
Fig. 2. Schematic details of preparing SCB samples from cylindrical specimens.
Fig. 4. Typical load-displacement curve and the schematic view of the fracture energies until and after failure.
Fig. 3. The fixture of mode I fracture test of semi-circular asphalt mixture specimen.
K Ic ¼
F cr pffiffiffiffiffiffi Y I pa 2Rt
ð1Þ
where Fcr is the peak load of the test (kN). R and t are the radius and thickness of the specimen (m) respectively, a is the notch depth (m) and Y is the shape factor, which was determined for different SCB specimens using finite element analysis by Ayatollahi and Aliha (2007) [60]. The fracture energies before and after failure, which are also named as stored fracture energy and residual fracture energy, are also known as criteria for investigating the resistance of materials against crack initiation and propagation respectively [61–64]. The stored and residual fracture energies are calculated as the area under the load-displacement curve before and after the peak load respectively as shown in Fig. 4. In this study, the aforementioned fracture energies were calculated for the specimens having 25 mm notch length and used as parameters of criteria for resistance against crack initiation and propagation. The J-integral, a well-known method for determining the crack resistance of asphaltic material [65–68], calculates the strain energy release rate for a crack in a body under monotonic loading
to describe the nonlinear fracture performance of material [43,69– 71]. The critical value of J-integral is also utilized as a criterion of crack resistance [42,72]. For calculating the value of Jc, the fracture energy until failure was calculated for each notch depth as the area under the load–displacement curves. A linear regression was then fitted on the fracture energy versus notch depths as shown in Fig. 5. The slope of the fitted line is then divided by the specimen thickness to calculate the value of Jc using Eq. (2).
Jc ¼
1 dU b da
ð2Þ
4. Results and discussion 4.1. SCB fracture test at 15 °C The results of SCB fracture tests conducted at 15 °C are illustrated in Figs. 6–8. Fig. 6 shows the fracture energy until the peak load of SCB specimens with 25 mm notch length. As illustrated at the charts of virgin mixtures, the fracture energy until failure improves by almost 70% by increasing the amount of glass fiber to 0.12%. Adding more fibers has an adverse impact on the cracking
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
Fig. 5. Linear regression of fracture energy versus notch depth.
Fig. 6. The results of fracture energy until failure at 15 °C for the specimens with 25 mm notch length.
5
Fig. 8. Critical stress intensity factors at temperature of 15 °C.
bearing capacity of the material is increased. As the load-bearing capacity of asphalt mixtures improves by increasing its stiffness and adding RAP material increases the stiffness of the mixtures, the fracture energy until failure enhances by increasing the percentage of RAP material. On the other hand, for the mixtures containing 0.06% and 0.12% glass fiber, the fracture energies peaked when 50% of RAP was used and then they leveled out by raising the RAP content, nevertheless, they were still much higher than that of the control mix. It is also shown that the fracture energies of all mixtures were improved by adding up to 0.12% fiber in the mixtures, which was occurred mainly due to the increase in stiffness of the material. The results of 0.18% fiber reinforced mixtures did not follow a specific trend, which could be due to the agglomeration of fibers. It should be noted that the fracture energies after the peak load, which is the criterion for resistance against crack propagation [43,62,73], were near to zero for all specimens at this temperature. The results of Jc values at 15 °C are presented in bar charts of Fig. 7. The Jc values follow the same trend as the results of fracture energy. It is also observed that the fibers are more effective in improving the Jc value than the fracture energy until failure. The results of critical stress intensity factors, which are shown in Fig. 8, agree with the results of Jc and fracture energy, and the values of KIc increase by increasing the RAP content and adding up to 0.12% fiber in the mixtures. 4.2. SCB fracture tests at 0 °C
Fig. 7. The results of Jc at temperature of 15 °C.
performance of the mixtures, which can be attributed to fiber agglomeration when an excessive amount of fiber is used. The overall trend shows that the fracture energy until failure increases by increasing the amount of RAP material in the mixtures. The reason is that at the temperature of 15 °C, the behavior of the mixtures is elastic and brittle, and the amounts of displacements are very low. Thus the fracture energy is more influenced by the stress capacity of the material than the resultant strain. Therefore, in this temperature, the fracture energy increases only when the load-
The results of Jc value and fracture energy until failure are presented in Figs. 9 and 10. At first glance at the charts it is apparent that unlike the results of the tests at 15 °C, the crack resistance of the mixtures declined by increasing the amount of RAP material at 0 °C. The reason is that in this temperature the fracture energy is a function of both load-bearing capacity and displacement. By adding RAP material the resulted displacement at the time of failure decreases substantially, and the increase in the peak load cannot compensate for the reduction in displacement. As a result, the fracture energy until failure declines by increasing the RAP content at this temperature. The fracture resistance of all mixtures increases by adding up to 0.12% glass fiber. The reason is that when asphalt mixtures are reinforced by high strength glass fibers, the fibers perform as a bridge on the cracks and prevent them from propagation. Moreover, adding fibers in the mixtures results in better coherence between the mastic and aggregates, which subsequently leads to less stress concentration and better performance [74]. However, the excessive amount of fiber in the mixtures leads to fiber agglomeration and weakens the performance of the mixtures. In this research, adding up to 0.12% fiber improved the cracking performance of the mixtures, and increasing the fiber content from
6
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
Fig. 9. The results of fracture energy until failure at 0 °C for the specimens with 25 mm notch length.
Fig. 11. The results of fracture energy after failure at 0 °C for the specimens with 25 mm notch length.
Fig. 10. The results of Jc at temperature of 0 °C.
0.12% to 0.18% led to a substantial decrease in the cracking resistance of the all studied mixtures. It can also be inferred from Figs. 9 and 10 that the glass fibers can completely compensate for the adverse impact of RAP material on cracking behavior of the mixtures at 0 °C, and the 100% RAP mixtures with 0.12% glass fiber have higher fracture energy and critical J integral than the control mix. The results of fracture energy after failure at 0 °C are shown in Fig. 11. It is seen that at this temperature the fracture energy after failure increases dramatically when up to 0.12% of glass fiber is added to the mixture. It can also be inferred from the results of Figs. 9 and 11 that the fibers are more effective in enhancing the fracture energy after failure than before failure. In other words, fibers have a greater impact on enhancing the resistance of the mixtures against crack propagation than crack initiation. It can also be observed that the impact of fibers diminishes by increasing the amount of RAP material. However, the resistance of 0.12% fiber reinforced mixtures containing up to 75% RAP against crack propagation is still higher than that of the control mixture. The 100% RAP mixtures containing 0.12% glass fiber are slightly weaker than the control mix in terms of crack propagation resistance at 0 °C. 4.3. SCB fracture tests at 15 °C The results of fracture energy until failure and Jc value at 15 °C, which are depicted in bar charts of Figs. 12 and 13 respectively, approve the results of the tests at 0 °C. In most mixtures, the opti-
Fig. 12. The results of fracture energy until failure at 15 °C for the specimens with 25 mm notch length.
mum content of glass fiber is 0.12%, and RAP material has an adverse effect on cracking performance of the mixtures at the temperature of 15 °C, which can be considerably compensated using glass fibers as an additive in the mixtures. It is also noteworthy that the Jc value of the 100% RAP mixtures is lower than the allowable threshold of ASTM D8044 [58], which is 0.5 Kj/m2. This shortcoming can be made up using 0.12% fiber to a fair extent, and the Jc value of 100% RAP mixtures reinforced with 0.12% glass fiber is only 12% lower than that of the control mixture. The results of fracture energy after failure at 15 °C are also shown in Fig. 14. It is apparent at the bar charts that fibers have a considerable effect on the crack propagation parameter of the mixtures, and the crack propagation resistances of all mixtures have almost tripled when 0.12% glass fiber is used. The results are in agreement with the results at 0 °C and follow the same trend.
4.4. The effect of temperature The effect of temperature on the fracture energy and the critical J integral is presented at Fig. 15. As shown, the crack resistance of asphalt mixtures increases when the temperature rises from 15 °C to 0 °C. Afterward, increasing the temperature leads to a decrease in the crack resistance of asphalt mixtures. The purpose
7
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
5. Crack resistance prediction models In this research, a multiple regression model was developed for predicting the fracture energy and the critical J integral of asphalt mixtures in terms of temperature, RAP content and fiber content using the experimental test results of this study. The model was established by adopting maximum response design using Minitab 18 by combining three parameters for total 240 test data, which are presented as Eqs. (3) and (4).
Fracture energy until failure ¼ 3:609 0:00985X1 þ 30:24X2 þ 0:0653X3 150:4X22 0:006492X32 0:000932X1 X3 0:1988X2 X3
Fig. 13. The results of Jc at temperature of 15 °C.
ð3Þ
Jc ¼ 2:926 0:01031X1 þ 28:77X2 þ 0:0549X3 137:3X22 0:00577X32 0:001234X1 X3
ð4Þ
where X1 is the RAP content (%), X2 is the glass fiber content (%) and X3 is the temperature (°C). The R2 values, which represent the statistical correlation between the fit line and experimental data, for fracture energy until failure and Jc value are 72.71% and 63.06% respectively. The probability values (P-value), the probability that, when the null hypothesis is true, were under 0.001% for both models, which show the significance of the differences between the results. The effects of each variable on the model responses and the normal probabil-
Fig. 14. The results of fracture energy after failure at 15 °C for the specimens with 25 mm notch length.
is that as mentioned previously, the fracture energy is a function of load-bearing capacity and the resultant displacement. At minus temperatures, the load-bearing capacity is high, and the displacements are very low. By increasing the temperature, the peak load declines and the displacement increases. As shown in Fig. 16, at the temperature of 0 °C, the positive effect of displacement increase predominates the negative impact of peak load decrease, and the fracture energy becomes maximum.
Fig. 16. Typical load–displacement curves of the asphalt mixtures tested at temperatures of 15, 0 and 15 °C.
Fig. 15. The effect of temperature on fracture energy and Jc of studied mixtures.
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
(a)
Fracture energy until failure
8
(b)
R2 = 72.71%
Fig. 17. The plots of (a) trend of changing of the fracture energy until failure against the studied variables, (b) normal probability plot of the prediction model for Fracture energy until failure.
Jc (kj/m2)
(a)
R2 = 63.06%
Fig. 18. The plots of (a) trend of changing of the fracture energy until failure against the studied variables, (b) Normal probability plot of the prediction model for Jc value.
ity plots of the prediction models are represented at Figs. 17 and 18. It can be seen that the models can properly predict the trend of changes. It is also shown that the maximum crack resistance occurs at a temperature between 0 °C and 10 °C when the percentages of RAP and fiber are 0% and 0.1% respectively. According to the levels of correlations of the models presented in Figs. 17 and 18,
the multiple regression models have a fair correlation with the experimental test results. This is mainly owing to the existence of few points that have large residuals and do not fit by the equations, which have a strong adverse influence on the level of correlations and are shown in normal probability plot of the prediction models. Other techniques such as the artificial neural network
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
(ANN) and Adaptive neuro-fuzzy inference system (ANFIS) can also be alternatives to predict the data with a better level of correlation [75]. 6. Conclusion In this study, glass fibers were used as a modifier in asphalt mixtures containing high contents of RAP material to compensate for the adverse effect of RAP material on cracking performance of the mixtures. For this purpose, different percentages of glass fibers were used as an additive in the asphalt mixtures containing different percentages of RAP material, and the SCB fracture tests were conducted at temperatures of 15, 0 and 15 °C. The results indicated that the positive effect of glass fibers on cracking performance of the recycled mixtures can compensate for the adverse impact of RAP material on the cracking behavior of the recycled mixtures, and the fracture energy of fiber-reinforced recycled mixtures was eider better than or similar to that of the control mix in most cases. However, more investigations about other aspects of the fiber-reinforced recycled asphalt mixtures such as fatigue and mode II fracture performance are needed in future studies. Other tentative conclusions are listed as follows: From the fracture test results of virgin asphalt mixtures, using up to 0.12% of glass fiber resulted in a significant improvement in the crack resistance of asphalt mixtures. Adding more fibers declined the cracking performance of the mixtures. However, the mixtures containing 0.18% fiber still performed better than the control mixture in terms of crack resistance. At the temperature of 15 °C, the fracture performance improved by increasing the RAP content and glass fibers due to the increase in stiffness of the mixtures. At temperatures of 0 and 15 °C, the crack resistance of the mixtures reduced by increasing the RAP content. The decline was reversible to a great extent when 0.12% of glass fiber was used as an additive in the mixtures. The fracture energy of the SCB specimens with 25 mm notch lengths was in a fair agreement with the Jc results at all temperatures. A regression model with a fair level of correlation was fitted on the results of fracture energy until failure and Jc values.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References [1] H. Ziari, A. Moniri, N. Norouzi, The effect of nanoclay as bitumen modifier on rutting performance of asphalt mixtures containing high content of rejuvenated reclaimed asphalt pavement, Pet. Sci. Technol. (2019) 1–6, https://doi.org/10.1080/10916466.2018.1471489. [2] M.J. Ayazi, A. Moniri, P. Barghabany, Moisture susceptibility of warm mixedreclaimed asphalt pavement containing Sasobit and Zycotherm additives, Pet. Sci. Technol. 35 (9) (2017) 890–895. [3] H. Behbahani, M.J. Ayazi, A. Moniri, Laboratory investigation of rutting performance of warm mix asphalt containing high content of reclaimed asphalt pavement, Pet. Sci. Technol. 35 (15) (2017) 1556–1561. [4] H. Ziari, A. Moniri, M.J. Ayazi, M. Nakhaei, Investigation of rutting performance of wma mixtures containing copper slag, Int. J. Transport. Eng. 3 (3) (2016) 227–235. [5] M. Fakhri, A.R. Ghanizadeh, An experimental study on the effect of loading history parameters on the resilient modulus of conventional and SBS-modified asphalt mixes, Constr. Build. Mater. 53 (2014) 284–293. [6] H. Haghshenas, H. Nabizadeh, Y.-R. Kim, and K. Santosh, ‘‘Research on high-rap asphalt mixtures with rejuvenators and WMA additives,” 2016.
9
[7] N.H. Tran, A. Taylor, R. Willis, ‘‘Effect of rejuvenator on performance properties of HMA mixtures with high RAP and RAS contents,” NCAT Report, pp. 12–05, 2012. [8] R.B. Mallick, K.A. O’Sullivan, M. Tao, R. Frank, ‘‘Why not use rejuvenator for 100% RAP recycling?,” 2010. [9] X. Shu, B. Huang, and D. Vukosavljevic, ‘‘Evaluation of cracking resistance of recycled asphalt mixture using semi-circular bending test,” in Paving Materials and Pavement Analysis, 2010, pp. 58–65. [10] J.R. Willis, P. Turner, G. Julian, A.J. Taylor, N. Tran, F. Padula, ‘‘Effects of changing virgin binder grade and content on RAP mixture properties,” NCAT Report, no. 12-03, 2012. [11] W. Mogawer, T. Bennert, J.S. Daniel, R. Bonaquist, A. Austerman, A. Booshehrian, Performance characteristics of plant produced high RAP mixtures, Road Mater. Pav. Design 13 (sup1) (2012) 183–208. [12] H. Ozer, I.L. Al-Qadi, P. Singhvi, T. Khan, J. Rivera-Perez, A. El-Khatib, Fracture characterization of asphalt mixtures with high recycled content using Illinois semicircular bending test method and flexibility index, Transp. Res. Rec. 2575 (1) (2016) 130–137. [13] Z. Zhou, X. Gu, F. Ni, Q. Li, X. Ma, Cracking resistance characterization of asphalt concrete containing reclaimed asphalt pavement at intermediate temperatures, Transp. Res. Rec. 2633 (1) (2017) 46–57. [14] M. Zaumanis, R.B. Mallick, Review of very high-content reclaimed asphalt use in plant-produced pavements: state of the art, Int. J. Pavement Eng. 16 (1) (2015) 39–55. [15] M. Ameri, A. Mansourkhaki, D. Daryaee, Evaluation of fatigue behavior of asphalt binders containing reclaimed asphalt binder using simplified viscoelastic continuum damage approach, Constr. Build. Mater. 202 (2019) 374–386. [16] A. Mansourkhaki, M. Ameri, D. Daryaee, Application of different modifiers for improvement of chemical characterization and physical-rheological parameters of reclaimed asphalt binder, Constr. Build. Mater. 203 (2019) 83–94. [17] T.B. Moghaddam, H. Baaj, The use of rejuvenating agents in production of recycled hot mix asphalt: a systematic review, Constr. Build. Mater. 114 (2016) 805–816. [18] Z. Zhou, X. Gu, Q. Dong, F. Ni, Y. Jiang, Rutting and fatigue cracking performance of SBS-RAP blended binders with a rejuvenator, Constr. Build. Mater. 203 (2019) 294–303. [19] M. Zaumanis, R.B. Mallick, L. Poulikakos, R. Frank, Influence of six rejuvenators on the performance properties of Reclaimed Asphalt Pavement (RAP) binder and 100% recycled asphalt mixtures, Constr. Build. Mater. 71 (2014) 538–550. [20] M. Zaumanis, R.B. Mallick, R. Frank, Evaluation of different recycling agents for restoring aged asphalt binder and performance of 100% recycled asphalt, Mater. Struct. 48 (8) (2015) 2475–2488. [21] S. Kodippily, G. Holleran, T.F. Henning, Deformation and cracking performance of recycled asphalt paving mixes containing polymer-modified binder, Road Mater. Pavement Design 18 (2) (2017) 425–439. [22] Z. Zhou, X. Gu, Q. Li, F. Ni, R. Yuan, Use of rejuvenator, styrene-butadiene rubber latex, and warm-mix asphalt technology to achieve conventional mixture performance with 50% reclaimed asphalt pavement, Transport. Res. Rec. J. Transp. Res. Board 2575 (2016) 160–167. [23] R. S. McDaniel, Fiber additives in asphalt mixtures (no. Project 20-05 (Topic 45-15)). 2015. [24] Z. Dehghan, A. Modarres, Evaluating the fatigue properties of hot mix asphalt reinforced by recycled PET fibers using 4-point bending test, Constr. Build. Mater. 139 (2017) 384–393, https://doi.org/10.1016/ j.conbuildmat.2017.02.082. [25] P. Park, S. El-Tawil, S.-Y. Park, A.E. Naaman, Cracking resistance of fiber reinforced asphalt concrete at 20°C, Constr. Build. Mater. 81 (2015) 47–57, https://doi.org/10.1016/j.conbuildmat.2015.02.005. [26] S.M. Abtahi, M. Sheikhzadeh, S.M. Hejazi, Fiber-reinforced asphalt-concrete–a review, Constr. Build. Mater. 24 (6) (2010) 871–877. [27] X. Qin, A. Shen, Y. Guo, Z. Li, Z. Lv, Characterization of asphalt mastics reinforced with basalt fibers, Constr. Build. Mater. 159 (2018) 508–516. [28] A. Mansourian, A. Razmi, M. Razavi, Evaluation of fracture resistance of warm mix asphalt containing jute fibers, Constr. Build. Mater. 117 (2016) 37–46. [29] C.J. Slebi-Acevedo, P. Lastra-González, P. Pascual-Muñoz, D. Castro-Fresno, Mechanical performance of fibers in hot mix asphalt: a review, Constr. Build. Mater. 200 (2019) 756–769. [30] F. Morea, R. Zerbino, Improvement of asphalt mixture performance with glass macro-fibers, Constr. Build. Mater. 164 (2018) 113–120. [31] A. Najd, Z. Chao, G. Ying, Experiments of fracture behavior of glass fiber reinforced asphalt concrete, J. Chang’an Univers. (Nat. Sci. Ed.) 25 (3) (2005). [32] S.H. Khanghahi, A. Tortum, Determination of the optimum conditions for gilsonite and glass fiber in HMA under Mixed Mode I/III loading in fracture tests, J. Mater. Civ. Eng. 30 (7) (2018) 04018130. [33] M. Enieb, A. Diab, X. Yang, Short-and long-term properties of glass fiber reinforced asphalt mixtures, Int. J. Pavement Eng. (2019) 1–13. [34] M. Aliha, H. Fattahi Amirdehi, Fracture toughness prediction using Weibull statistical method for asphalt mixtures containing different air void contents, Fatigue Fract. Eng. Mater. Struct. 40 (1) (2017) 55–68. [35] M. Sabouri, D. Mirzaeian, A. Moniri, Effectiveness of linear amplitude sweep (LAS) asphalt binder test in predicting asphalt mixtures fatigue performance, Constr. Build. Mater. 171 (2018) 281–290.
10
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
[36] M. Fakhri, E.H. Kharrazi, M. Aliha, Mixed mode tensile–In plane shear fracture energy determination for hot mix asphalt mixtures under intermediate temperature conditions, Eng. Fract. Mech. 192 (2018) 98–113. [37] M.R.M. Aliha, H. Behbahani, H. Fazaeli, M.H. Rezaifar, Study of characteristic specification on mixed mode fracture toughness of asphalt mixtures, Constr. Build. Mater. 54 (2014/03/15/ 2014,) 623–635, https://doi.org/10.1016/ j.conbuildmat.2013.12.097. [38] M. Aliha, H. Fazaeli, S. Aghajani, F.M. Nejad, Effect of temperature and air void on mixed mode fracture toughness of modified asphalt mixtures, Constr. Build. Mater. 95 (2015) 545–555. [39] M. Aliha, M. Sarbijan, Effects of loading, geometry and material properties on fracture parameters of a pavement containing top-down and bottom-up cracks, Eng. Fract. Mech. 166 (2016) 182–197. [40] M.R.M. Aliha, A. Bahmani, S. Akhondi, A novel test specimen for investigating the mixed mode I+III fracture toughness of hot mix asphalt composites – Experimental and theoretical study, Int. J. Solids Struct. 90 (2016) 167–177, https://doi.org/10.1016/j.ijsolstr.2016.03.018. [41] P.J. Haghighat Pour, M.R.M. Aliha, M.R. Keymanesh, Evaluating mode I fracture resistance in asphalt mixtures using edge notched disc bend ENDB specimen with different geometrical and environmental conditions, Eng. Fract. Mech. 190 (2018) 245–258, https://doi.org/10.1016/j.engfracmech.2017.11.007. [42] M. Ameri, S. Nowbakht, M. Molayem, M. Aliha, Investigation of fatigue and fracture properties of asphalt mixtures modified with carbon nanotubes, Fatigue Fract. Eng. Mater. Struct. 39 (7) (2016) 896–906. [43] G. Saha, K.P. Biligiri, Fracture properties of asphalt mixtures using semicircular bending test: a state-of-the-art review and future research, Constr. Build. Mater. 105 (2016) 103–112. [44] M. Aliha, M. Fakhri, E.H. Kharrazi, F. Berto, The effect of loading rate on fracture energy of asphalt mixture at intermediate temperatures and under different loading modes, Frattura ed Integrità Strutturale 12 (43) (2018) 113–132. [45] M. Aliha, H. Behbahani, H. Fazaeli, M. Rezaifar, Study of characteristic specification on mixed mode fracture toughness of asphalt mixtures, Constr. Build. Mater. 54 (2014) 623–635. [46] M. Ameri, A. Mansourian, M. Heidary Khavas, M. Aliha, M. Ayatollahi, Cracked asphalt pavement under traffic loading–A 3D finite element analysis, Eng. Fract. Mech. 78 (8) (2011) 1817–1826. [47] M. Ameri, A. Mansourian, S. Pirmohammad, M. Aliha, M. Ayatollahi, Mixed mode fracture resistance of asphalt concrete mixtures, Eng. Fract. Mech. 93 (2012) 153–167. [48] T. Tam, A. Bhatnagar, 1 – High-performance ballistic fibers and tapes, in: Lightweight Ballistic Composites, Second Edition., Woodhead Publishing, Bhatnagar Ed., 2016, pp. 1–39. [49] A.D/DM-17, Standard Test Methods for Quantitative Extraction of Asphalt Binder from Asphalt Mixtures, ASTM International, West Conshohocken, PA, 2017. [50] H. Ziari, A. Moniri, P. Bahri, Y. Saghafi, The effect of rejuvenators on the aging resistance of recycled asphalt mixtures, Constr. Build. Mater. 224 (2019) 89– 98. [51] A.D/DM-12, Standard practice for recovery of asphalt from solution using the rotary evaporator, ASTM International, West Conshohocken, 2012. [52] M. Zaumanis, R.B. Mallick, R. Frank, Determining optimum rejuvenator dose for asphalt recycling based on Superpave performance grade specifications, Constr. Build. Mater. 69 (2014) 159–166. [53] A.D. T245, Standard Method of Test for Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus, AASHTO, Washington, DC, 2004. [54] D. ASTM, ‘‘3515, Standard Specification for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures,” Annual Book of Standards, vol. 4, 2004. [55] Hassan Ziari, Ali Moniri, Reza Imaninasab, Mostafa Nakhaei, Effect of copper slag on performance of warm mix asphalt, Int. J. Pavement Eng. 20 (7) (2019) 775–781, https://doi.org/10.1080/10298436.2017.1339884.
[56] H. Ziari, M. Nakhaei, A. Akbari Nasrekani, A. Moniri, Characterization of rutting resistance of EBS-modified asphalt mixtures, Pet. Sci. Technol. 34 (13) (2016) 1107–1112. [57] A.H. Korayem, H. Ziari, M. Hajiloo, A. Moniri, Rutting and fatigue performance of asphalt mixtures containing amorphous carbon as filler and binder modifier, Constr. Build. Mater. 188 (2018) 905–914. [58] A. Standard, ‘‘D8044-16: Standard Test Method for Evaluation of Asphalt Mixture Cracking Resistance using the Semi-Circular Bend Test (SCB) at Intermediate Temperatures.,” Book of Standards, vol. 4, 2016. [59] H.R. Fattahi Amirdehi, M.R.M. Aliha, A. Moniri, A.R. Torabi, Using the generalized maximum tangential stress criterion to predict mode II fracture of hot mix asphalt in terms of mode I results – A statistical analysis, Constr. Build. Mater. 213 (2019) 483–491, https://doi.org/10.1016/ j.conbuildmat.2019.04.067. [60] M. Ayatollahi, M. Aliha, Wide range data for crack tip parameters in two disctype specimens under mixed mode loading, Comput. Mater. Sci. 38 (4) (2007) 660–670. [61] G. Saha, K.P. Biligiri, Fracture damage evaluation of asphalt mixtures using Semi-Circular Bending test based on fracture energy approach, Eng. Fract. Mech. 142 (2015) 154–169. [62] M. Minhajuddin, G. Saha, K.P. Biligiri, Crack propagation parametric assessment of modified asphalt mixtures using linear elastic fracture mechanics approach, J. Test. Eval. 44 (1) (2015) 471–483. [63] M. Kuruppu, Y. Obara, M. Ayatollahi, K. Chong, T. Funatsu, ISRM-suggested method for determining the mode I static fracture toughness using semicircular bend specimen, Rock Mech. Rock Eng. 47 (1) (2014) 267–274. [64] H. Ziari, A. Moniri, Laboratory evaluation of the effect of synthetic Polyolefinglass fibers on performance properties of hot mix asphalt, Constr. Build. Mater. 213 (2019) 459–468, https://doi.org/10.1016/j.conbuildmat.2019.04.084. [65] H. Jahanbakhsh, P. Hosseini, F.M. Nejad, M. Habibi, Intermediate temperature fracture resistance evaluation of cement emulsified asphalt mortar, Constr. Build. Mater. 197 (2019) 1–11. [66] M. Ling, X. Luo, Y. Chen, S. Hu, R.L. Lytton, A calibrated mechanics-based model for top-down cracking of asphalt pavements, Constr. Build. Mater. 208 (2019) 102–112, https://doi.org/10.1016/j.conbuildmat.2019.02.090. [67] W. Song, B. Huang, X. Shu, Influence of warm-mix asphalt technology and rejuvenator on performance of asphalt mixtures containing 50% reclaimed asphalt pavement, J. Cleaner Prod. 192 (2018) 191–198. [68] X. Luo, Y. Zhang, R.L. Lytton, Implementation of pseudo J-integral based Paris’ law for fatigue cracking in asphalt mixtures and pavements, Mater. Struct. 49 (9) (2016) 3713–3732. [69] Z. Wu, L.N. Mohammad, L. Wang, M.A. Mull, Fracture resistance characterization of superpave mixtures using the semi-circular bending test, J. ASTM Int. 2 (3) (2005) 1–15. [70] H. Kuai, H. Lee, G. Zi, S. Mun, Application of generalized J-integral to crack propagation modeling of asphalt concrete under repeated loading, Transp. Res. Rec. J. Transp. Res. Board 2127 (2009) 72–81. [71] Y.-R. Kim, J. Zhang, H. Ban, Moisture damage characterization of warm-mix asphalt mixtures based on laboratory-field evaluation, Constr. Build. Mater. 31 (2012) 204–211. [72] L.N. Mohammad, M. Kim, M. Elseifi, Characterization of asphalt mixture’s fracture resistance using the semi-circular bending (SCB) test, in: 7th RILEM International Conference on Cracking in Pavements, Springer, 2012, pp. 1–10. [73] K.P. Biligiri, S. Said, H. Hakim, Asphalt mixtures, Int. J. Pavement Res. Technol. 5 (4) (2012) 209–217. [74] H. Fazaeli, Y. Samin, A. Pirnoun, A.S. Dabiri, Laboratory and field evaluation of the warm fiber reinforced high performance asphalt mixtures (case study Karaj-Chaloos Road), Constr. Build. Mater. 122 (2016) 273–283. [75] H. Ziari, A. Amini, A. Goli, D. Mirzaiyan, Predicting rutting performance of carbon nano tube (CNT) asphalt binders using regression models and neural networks, Constr. Build. Mater. 160 (2018) 415–426.
Contents lists available at ScienceDirect
Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Crack resistance of hot mix asphalt containing different percentages of reclaimed asphalt pavement and glass fiber Hassan Ziari a, M.R.M. Aliha b,⇑, Ali Moniri c, Yasha Saghafi c a
Asphalt and Bitumen Research Center (ABRC), School of Civil Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran, Iran Welding and Joining Research Center, School of Industrial Engineering, Iran University of Science and Technology, Narmak, 16846-13114 Tehran, Iran c School of Civil Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran, Iran b
h i g h l i g h t s The cracking resistance of asphalt mixtures declines by adding RAP at 0 °C and 15 °C. Glass fibers are beneficial for enhancing the cracking resistance of asphalt mixtures. The positive effect of glass fibers can compensate for the adverse impact of RAP material. The use of RAP material improves cracking performance at 15 °C.
a r t i c l e
i n f o
Article history: Received 12 April 2019 Received in revised form 20 August 2019 Accepted 15 September 2019
Keywords: Cracking behavior SCB fracture test 100% RAP mixtures Reclaimed asphalt pavement Recycled asphalt
a b s t r a c t Escalating the price of asphalt binder and environmental issues have led to an increasing desire to use high amounts of reclaimed asphalt pavement (RAP) material in asphalt mixtures. However, increasing the RAP content may have negative effects on some characteristics of asphalt mixtures, such as cracking resistance. Therefore, finding an approach to compensate for the negative impacts of RAP material may be considered as a solution to raise the RAP content in asphalt mixtures. Fibers are known as one of the modifiers that are added directly to the mixtures and enhance the cracking resistance of asphaltic materials. Therefore, in this study, the cracking behavior of asphalt mixtures containing different percentages of RAP material in combination with glass fibers was investigated using the semi-circular bending (SCB) fracture tests at temperatures of 15, 0 and 15 °C. The results showed that using up to 0.12% glass fiber leads to a significant enhancement in resistance of all mixtures against crack initiation and propagation. Moreover, it was found that the negative impact of RAP material on the crack resistance of asphalt mixtures is reversible to a great extent using 0.12% glass fiber, and 100% RAP mixtures are applicable without any significant reduction in crack resistance. Ó 2019 Elsevier Ltd. All rights reserved.
1. Introduction The huge use of aggregates as a raw material in asphalt pavements has depleted the rock and aggregate resources [1]. Furthermore, the high price of asphalt binder has caused financial problems in asphalt production. Reusing of reclaimed asphalt pavement (RAP) in new asphalt mixtures can be an approach to reduce the usage of valuable aggregates and expensive binder [2–5]. Less aggregate extraction, transportation, and processing operations can also be mentioned as other advantages of recycling RAP material [6]. Despite aforementioned benefits, there are some problems associated with the use of high contents of RAP material ⇑ Corresponding author. E-mail address: [email protected] (M.R.M. Aliha). https://doi.org/10.1016/j.conbuildmat.2019.117015 0950-0618/Ó 2019 Elsevier Ltd. All rights reserved.
in asphalt mixtures such as a reduction in cracking resistance and poor low-temperature performance due to the brittleness of its aged binder [7–9]. For this reason, most agencies do not allow high contents of RAP material in newly produces asphalt mixtures [10,11]. Shu et al in 2007 investigated the crack resistance of asphalt mixtures containing up to 30% of RAP material using the J-integral principles [9]. They showed that the cracking resistance of asphalt mixtures declines by increasing the amount of RAP material. The fracture resistance of asphalt mixtures containing different percentages of RAP and recycled asphalt shingles (RAS) material was evaluated using the fracture energy approach on semi-circular bending (SCB) specimens at temperatures of 12 °C and 25 °C [12]. It was found that the fracture energy of asphalt mixtures at both temperatures significantly declined when 40% of RAP material was used. Zhou et al (2017) investigated the frac-
2
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
ture energy of asphalt mixtures with up to 50% of RAP material at intermediate temperatures of 15 °C and 25 °C [13]. The results approved the previous researches, and the cracking resistance of asphalt mixtures declined by raising the RAP content. Therefore, improving the low-temperature performance and cracking resistance of the RAP mixtures can provide the possibility to increase the RAP content in asphalt mixtures. There have been some attempts to compensate for the weakness of recycled mixtures against cracking. Different types of rejuvenators and modifiers are introduced to enhance the cracking performance of recycled asphalt mixtures [14–18]. Zaumanis et al. (2014) compared the performance of six different rejuvenators in modifying the RAP aged binder. It was indicated that the performance grade of aged binder can be completely restored using waste vegetable oils, waste vegetable grease and organic oils [19]. However, in another study, Zaumanis and Mallick showed that the fracture work of rejuvenated 100% RAP mixtures is significantly lower than that of the virgin mixture [20]. Kodippily et al. (2016) used styrene–butadiene–styrene (SBS) as virgin binder modifier in 30% RAP mixtures to make up the adverse impacts of RAP material. It was indicated that the lost resistance against reflective cracking is almost recoverable when SBS modified virgin binder is used [21]. Zhou et al. investigated two kinds of rejuvenators and styrene-butadiene rubber (SBR) latex modified virgin binder in warm mix asphalt (WMA) containing 50% RAP. They showed that the 50% RAP mixtures modified with rejuvenator and SBR latex performed better than the conventional HMA mixtures in terms of low temperature and fatigue performance [22]. It can be seen in previous researches that using polymer modified virgin binders in combination with rejuvenators can restore the performance of recycled asphalt mixtures. However, as the content of virgin binder decreases by increasing the RAP content, using polymer modified binders cannot be efficient for mixtures containing high contents of RAP material and specifically, 100% RAP mixtures. Moreover, polymer modified binders are not applicable when the hot in-place recycling method is employed. Therefore, finding an alternative modifier which is added directly to the mixture can be a more proper solution to compensate for the negative impact of the aged binder of RAP material on middle and lowtemperature performance of asphalt mixture. Fibers are a kind of modifier that is added directly to the mixture and improve the resistance of asphalt mixtures against cracking and fatigue [23– 29]. Glass fibers have shown a good potential to improve the rutting and cracking performance of asphalt mixtures [30–32]. Improved healing capability and higher rutting, moisture and fatigue resistance are also reported as benefits of glass fibers in asphalt mixtures [33]. Fatigue and cracking are of the most prevalent asphalt layer defects especially in areas with cold and harsh weather [34–36]. Initiation and propagation of cracks through the asphalt overlays are related to traffic loading, thermal stresses and temperature gradient [37–39]. Fracture mechanics is one of the techniques for evaluating the crack resistance of asphalt mixtures [40–44]. The semicircular bending (SCB) fracture test is known as a popular method for evaluating fracture performance of asphalt mixtures due to the convenience in sample preparation and its reliable results [36,38,44–47]. Cracking is more probable at low temperatures due to the brittleness of the binders and mixtures [38]. Since the use of RAP material increases the brittleness of asphalt mixtures, the cracking behavior of the mixtures containing high contents of RAP material is questionable. The main objective of this research is to evaluate the effect of glass fiber reinforcement on cracking resistance of recycled asphalt mixtures and the optimum fiber content in asphalt mixtures containing different percentages of RAP material. For this purpose, asphalt mixtures containing 25%, 50%, 75% and 100% RAP and
Cyclogen as rejuvenator were reinforced with different percentages of glass fiber (0.06%, 0.12%, and 0.18% by weight of total mixture), and evaluated in terms of cracking performance using the J integral procedure at temperatures of 15, 0 and 15 °C. The results were compared to the results of mixtures without RAP and fiber as a control mixture.
2. Materials 2.1. Binder The binder used in this research was a PG 64-16 grade asphalt binder provided from Pasargad oil company. Table 1 shows the physical properties of this binder.
2.2. Aggregates Limestone aggregates were used as raw material for producing the asphalt mixtures. The physical characteristics of the aggregates were tested, and the results are listed in Table 2.
2.3. Fiber Glass fibers, which are categorized as High-performance ballistic fibers, are used in this study as asphalt mixture modifier. These fibers are manufactured of recycled crushed glasses via pultrusion process as explained by Tam and Bhatnagar [48]. An example image of glass fiber used in this study is shown in Fig. 1. The properties of fibers used in this study are summarized in Table 3.
2.4. RAP material and rejuvenator The RAP material used in this study was obtained from the milling operation of a freeway in Tehran. The binder content and gradation of the RAP material were determined after extracting its binder according to ASTM D2172 [49]. This procedure was carried out once for fine aggregates (passing sieve No 8) and once for the retained material on 2.36, 4.75, 12.5 and 19 mm sieves. The results, which were then used for gradation of the total mixture, are listed in Table 4. Cyclogen, which is categorized as aromatic extracts [6,50], was used in this study as the rejuvenator. The physical properties of this rejuvenator are provided in Table 5. The aged binder of RAP material was recovered using the rotary evaporator according to ASTM D5404-17 [51]. The optimum amount of rejuvenator was calculated as 6% of aged binder regarding the performance grade of the rejuvenated binder for both rejuvenators. For this purpose, the binder of the RAP material was recovered using ASTM D5404. Then different percentages of rejuvenator were added to the recovered binder until the lower grade reached the lower grade of the virgin binder [35,52]. In this research, the PG grade of the recovered RAP binder was PG 82-10, which was upgraded to PG 70-16 by adding the rejuvenator.
3. Methodology This research consists of three main stages. At first, the optimum binder content (OBC) of each mixture was determined using the Marshall procedure based on AASHTO T245 [53]. Afterward, cylindrical specimens with a diameter of 150 mm containing different percentages of RAP (0, 25, 50, 75 and 100%) and glass fiber (0, 0.06%, 0.12%, and 0.18% by weight of total mixture) were produced and cut to SCB specimens. Then, the SCB fracture tests at 15, 0 and 15 °C were conducted to evaluate the cracking resistance of the mixtures.
Table 1 Physical properties of asphalt binder. Test
Unit
Standard
PG 64-16
Viscosity test at 135 °C (cSt) Penetration test (0.1 mm) Ductility test (cm) Softening point (°C) Flash point (°C) Specific gravity
centistokes 0.1 mm cm °C °C g/cm3
ASTM ASTM ASTM ASTM ASTM ASTM
364 66 100 49 290 1.018
D113 D5 D113 D36 D92 D70
3
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
venator was added directly to the RAP material and mixed together. The rejuvenated RAP material was then mixed with virgin aggregates and fibers, which were gradually added to the mix. Afterward, the virgin binder was added to the mixture and intermixed. The total mixtures were then placed in compaction temperature for two hours [6]. The prepared mixtures were then placed in superpave gyratory compactor (SGC) with 150 mm diameter mold and compacted until reaching the target air void of 7% using the theoretical maximum specific gravity and the desirable bulk specific gravity [35,55–57]. The compacted cylindrical specimens were cut to SCB specimens according to ASTM D 8044 [58]. Artificial notches with 0.3 mm width and lengths of 25 mm, 32 mm and 38 mm were then created in the middle of SCB specimens. The schematic details of preparing SCB samples from cylindrical specimens are shown in Fig. 2.
Table 2 Physical properties of the limestone aggregates used in this research. Test
Unit
Coarse aggregate specific gravity Fine aggregate specific gravity Los Angeles abrasion value (LAV) Sodium sulfate soundness (SS) Sand equivalent (SE) Flakiness
3
g/cm g/cm3 % % % %
Standard
Result
ASTM C127 ASTM C128 ASTM C131 ASTM C88 ASTM T176 BS-812
2.57 2.54 22.2 2.7 65 16.63
3.2. SCB fracture tests For conducting the SCB fracture tests, at first, all SCB samples were placed at target temperature at least for 8 h. A tensioncompression test machine with a fixture with a support distance of 127 mm was then used to apply monotonic load with a rate of 0.5 mm/min as shown in Fig. 3. All tests were conducted under mode I condition on SCB specimens with three notch lengths at temperatures of 15, 0 and 15 °C in accordance with ASTM D8044. Four replicates were conducted for each notch depth, and the fracture energy before and after the peak load and critical value of J integral (Jc) were determined for each mixture.
Fig. 1. Glass fiber used in this research.
Table 3 Mechanical and physical properties of the glass fiber used in this study. Feature
Unit
Glass fiber
Color Specific gravity Length Diameter Tensile strength Melting point Water absorption
– g/cm3 mm mm MPa °C %
White 1.18 12 <0.13 >1000 800–900 0
3.2.1. Crack resistance criteria The mode I fracture toughness (KIC) is defined as the fracture resistance criterion of asphalt mixtures at minus temperatures, at which the elastic behavior is dominant in asphalt mixture, and the linear elastic fracture conditions are met [40,59]. This parameter was calculated using Eq. (1) for the specimens having 25 mm notch depth tested at 15 °C.
3.1. Mix design and sample preparation Table 5 The physical characteristics of the rejuvenator used in this study.
The first stage of the mix design was aggregate gradation. All mixtures were graded based on the mid-curve of the recommendation of ASTM D3515 [54] with a nominal maximum aggregate size of 19 mm. The information in Table 4 was used to keep the aggregate gradations of each mixture similar to each other. After the Marshall procedure had been carried out, the optimum amounts of virgin binder required for the mixtures containing 0%, 25%, 50%, 75% and 100% RAP material was determined as 5.4%, 3.93%, 2.55%, 1.23% and 0.33% by weight of total mixture respectively. For preparing the specimens, virgin aggregates and RAP material was kept at 175 °C for 16 and 2 h respectively. Next, the reju-
Rejuvenator property
Rejuvenator
Base Physical state at room temperature Color Odor Water solubility Viscosity at 135 °C (s) Flash point (°C) Specific gravity (g/cm3)
Oil Liquid Black No No 10 218 0.973
Table 4 Binder content and gradation of sieved RAP material. Sieve size (mm)
19 12.5 4.75 2.36 0.3 0.075 Binder content (%)
Passing percentage RAP
RAP retained on 19 mm sieve
RAP retained on 12.5 mm sieve
RAP retained on 4.75 mm sieve
RAP retained on 2.36 mm sieve
RAP Passing through 2.36 mm sieve
100 98.2 69.3 47.2 15.8 6 5.4
4.8 4.8 4.8 4.8 3.7 2.9 5.2
100 6.2 6.2 6.2 4 3.5 5.2
100 100 7.1 7.1 4.6 2.7 5.4
100 100 100 9.7 5.3 3.1 5.6
100 100 100 100 26.1 7.2 6
4
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
Fig. 2. Schematic details of preparing SCB samples from cylindrical specimens.
Fig. 4. Typical load-displacement curve and the schematic view of the fracture energies until and after failure.
Fig. 3. The fixture of mode I fracture test of semi-circular asphalt mixture specimen.
K Ic ¼
F cr pffiffiffiffiffiffi Y I pa 2Rt
ð1Þ
where Fcr is the peak load of the test (kN). R and t are the radius and thickness of the specimen (m) respectively, a is the notch depth (m) and Y is the shape factor, which was determined for different SCB specimens using finite element analysis by Ayatollahi and Aliha (2007) [60]. The fracture energies before and after failure, which are also named as stored fracture energy and residual fracture energy, are also known as criteria for investigating the resistance of materials against crack initiation and propagation respectively [61–64]. The stored and residual fracture energies are calculated as the area under the load-displacement curve before and after the peak load respectively as shown in Fig. 4. In this study, the aforementioned fracture energies were calculated for the specimens having 25 mm notch length and used as parameters of criteria for resistance against crack initiation and propagation. The J-integral, a well-known method for determining the crack resistance of asphaltic material [65–68], calculates the strain energy release rate for a crack in a body under monotonic loading
to describe the nonlinear fracture performance of material [43,69– 71]. The critical value of J-integral is also utilized as a criterion of crack resistance [42,72]. For calculating the value of Jc, the fracture energy until failure was calculated for each notch depth as the area under the load–displacement curves. A linear regression was then fitted on the fracture energy versus notch depths as shown in Fig. 5. The slope of the fitted line is then divided by the specimen thickness to calculate the value of Jc using Eq. (2).
Jc ¼
1 dU b da
ð2Þ
4. Results and discussion 4.1. SCB fracture test at 15 °C The results of SCB fracture tests conducted at 15 °C are illustrated in Figs. 6–8. Fig. 6 shows the fracture energy until the peak load of SCB specimens with 25 mm notch length. As illustrated at the charts of virgin mixtures, the fracture energy until failure improves by almost 70% by increasing the amount of glass fiber to 0.12%. Adding more fibers has an adverse impact on the cracking
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
Fig. 5. Linear regression of fracture energy versus notch depth.
Fig. 6. The results of fracture energy until failure at 15 °C for the specimens with 25 mm notch length.
5
Fig. 8. Critical stress intensity factors at temperature of 15 °C.
bearing capacity of the material is increased. As the load-bearing capacity of asphalt mixtures improves by increasing its stiffness and adding RAP material increases the stiffness of the mixtures, the fracture energy until failure enhances by increasing the percentage of RAP material. On the other hand, for the mixtures containing 0.06% and 0.12% glass fiber, the fracture energies peaked when 50% of RAP was used and then they leveled out by raising the RAP content, nevertheless, they were still much higher than that of the control mix. It is also shown that the fracture energies of all mixtures were improved by adding up to 0.12% fiber in the mixtures, which was occurred mainly due to the increase in stiffness of the material. The results of 0.18% fiber reinforced mixtures did not follow a specific trend, which could be due to the agglomeration of fibers. It should be noted that the fracture energies after the peak load, which is the criterion for resistance against crack propagation [43,62,73], were near to zero for all specimens at this temperature. The results of Jc values at 15 °C are presented in bar charts of Fig. 7. The Jc values follow the same trend as the results of fracture energy. It is also observed that the fibers are more effective in improving the Jc value than the fracture energy until failure. The results of critical stress intensity factors, which are shown in Fig. 8, agree with the results of Jc and fracture energy, and the values of KIc increase by increasing the RAP content and adding up to 0.12% fiber in the mixtures. 4.2. SCB fracture tests at 0 °C
Fig. 7. The results of Jc at temperature of 15 °C.
performance of the mixtures, which can be attributed to fiber agglomeration when an excessive amount of fiber is used. The overall trend shows that the fracture energy until failure increases by increasing the amount of RAP material in the mixtures. The reason is that at the temperature of 15 °C, the behavior of the mixtures is elastic and brittle, and the amounts of displacements are very low. Thus the fracture energy is more influenced by the stress capacity of the material than the resultant strain. Therefore, in this temperature, the fracture energy increases only when the load-
The results of Jc value and fracture energy until failure are presented in Figs. 9 and 10. At first glance at the charts it is apparent that unlike the results of the tests at 15 °C, the crack resistance of the mixtures declined by increasing the amount of RAP material at 0 °C. The reason is that in this temperature the fracture energy is a function of both load-bearing capacity and displacement. By adding RAP material the resulted displacement at the time of failure decreases substantially, and the increase in the peak load cannot compensate for the reduction in displacement. As a result, the fracture energy until failure declines by increasing the RAP content at this temperature. The fracture resistance of all mixtures increases by adding up to 0.12% glass fiber. The reason is that when asphalt mixtures are reinforced by high strength glass fibers, the fibers perform as a bridge on the cracks and prevent them from propagation. Moreover, adding fibers in the mixtures results in better coherence between the mastic and aggregates, which subsequently leads to less stress concentration and better performance [74]. However, the excessive amount of fiber in the mixtures leads to fiber agglomeration and weakens the performance of the mixtures. In this research, adding up to 0.12% fiber improved the cracking performance of the mixtures, and increasing the fiber content from
6
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
Fig. 9. The results of fracture energy until failure at 0 °C for the specimens with 25 mm notch length.
Fig. 11. The results of fracture energy after failure at 0 °C for the specimens with 25 mm notch length.
Fig. 10. The results of Jc at temperature of 0 °C.
0.12% to 0.18% led to a substantial decrease in the cracking resistance of the all studied mixtures. It can also be inferred from Figs. 9 and 10 that the glass fibers can completely compensate for the adverse impact of RAP material on cracking behavior of the mixtures at 0 °C, and the 100% RAP mixtures with 0.12% glass fiber have higher fracture energy and critical J integral than the control mix. The results of fracture energy after failure at 0 °C are shown in Fig. 11. It is seen that at this temperature the fracture energy after failure increases dramatically when up to 0.12% of glass fiber is added to the mixture. It can also be inferred from the results of Figs. 9 and 11 that the fibers are more effective in enhancing the fracture energy after failure than before failure. In other words, fibers have a greater impact on enhancing the resistance of the mixtures against crack propagation than crack initiation. It can also be observed that the impact of fibers diminishes by increasing the amount of RAP material. However, the resistance of 0.12% fiber reinforced mixtures containing up to 75% RAP against crack propagation is still higher than that of the control mixture. The 100% RAP mixtures containing 0.12% glass fiber are slightly weaker than the control mix in terms of crack propagation resistance at 0 °C. 4.3. SCB fracture tests at 15 °C The results of fracture energy until failure and Jc value at 15 °C, which are depicted in bar charts of Figs. 12 and 13 respectively, approve the results of the tests at 0 °C. In most mixtures, the opti-
Fig. 12. The results of fracture energy until failure at 15 °C for the specimens with 25 mm notch length.
mum content of glass fiber is 0.12%, and RAP material has an adverse effect on cracking performance of the mixtures at the temperature of 15 °C, which can be considerably compensated using glass fibers as an additive in the mixtures. It is also noteworthy that the Jc value of the 100% RAP mixtures is lower than the allowable threshold of ASTM D8044 [58], which is 0.5 Kj/m2. This shortcoming can be made up using 0.12% fiber to a fair extent, and the Jc value of 100% RAP mixtures reinforced with 0.12% glass fiber is only 12% lower than that of the control mixture. The results of fracture energy after failure at 15 °C are also shown in Fig. 14. It is apparent at the bar charts that fibers have a considerable effect on the crack propagation parameter of the mixtures, and the crack propagation resistances of all mixtures have almost tripled when 0.12% glass fiber is used. The results are in agreement with the results at 0 °C and follow the same trend.
4.4. The effect of temperature The effect of temperature on the fracture energy and the critical J integral is presented at Fig. 15. As shown, the crack resistance of asphalt mixtures increases when the temperature rises from 15 °C to 0 °C. Afterward, increasing the temperature leads to a decrease in the crack resistance of asphalt mixtures. The purpose
7
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
5. Crack resistance prediction models In this research, a multiple regression model was developed for predicting the fracture energy and the critical J integral of asphalt mixtures in terms of temperature, RAP content and fiber content using the experimental test results of this study. The model was established by adopting maximum response design using Minitab 18 by combining three parameters for total 240 test data, which are presented as Eqs. (3) and (4).
Fracture energy until failure ¼ 3:609 0:00985X1 þ 30:24X2 þ 0:0653X3 150:4X22 0:006492X32 0:000932X1 X3 0:1988X2 X3
Fig. 13. The results of Jc at temperature of 15 °C.
ð3Þ
Jc ¼ 2:926 0:01031X1 þ 28:77X2 þ 0:0549X3 137:3X22 0:00577X32 0:001234X1 X3
ð4Þ
where X1 is the RAP content (%), X2 is the glass fiber content (%) and X3 is the temperature (°C). The R2 values, which represent the statistical correlation between the fit line and experimental data, for fracture energy until failure and Jc value are 72.71% and 63.06% respectively. The probability values (P-value), the probability that, when the null hypothesis is true, were under 0.001% for both models, which show the significance of the differences between the results. The effects of each variable on the model responses and the normal probabil-
Fig. 14. The results of fracture energy after failure at 15 °C for the specimens with 25 mm notch length.
is that as mentioned previously, the fracture energy is a function of load-bearing capacity and the resultant displacement. At minus temperatures, the load-bearing capacity is high, and the displacements are very low. By increasing the temperature, the peak load declines and the displacement increases. As shown in Fig. 16, at the temperature of 0 °C, the positive effect of displacement increase predominates the negative impact of peak load decrease, and the fracture energy becomes maximum.
Fig. 16. Typical load–displacement curves of the asphalt mixtures tested at temperatures of 15, 0 and 15 °C.
Fig. 15. The effect of temperature on fracture energy and Jc of studied mixtures.
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
(a)
Fracture energy until failure
8
(b)
R2 = 72.71%
Fig. 17. The plots of (a) trend of changing of the fracture energy until failure against the studied variables, (b) normal probability plot of the prediction model for Fracture energy until failure.
Jc (kj/m2)
(a)
R2 = 63.06%
Fig. 18. The plots of (a) trend of changing of the fracture energy until failure against the studied variables, (b) Normal probability plot of the prediction model for Jc value.
ity plots of the prediction models are represented at Figs. 17 and 18. It can be seen that the models can properly predict the trend of changes. It is also shown that the maximum crack resistance occurs at a temperature between 0 °C and 10 °C when the percentages of RAP and fiber are 0% and 0.1% respectively. According to the levels of correlations of the models presented in Figs. 17 and 18,
the multiple regression models have a fair correlation with the experimental test results. This is mainly owing to the existence of few points that have large residuals and do not fit by the equations, which have a strong adverse influence on the level of correlations and are shown in normal probability plot of the prediction models. Other techniques such as the artificial neural network
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
(ANN) and Adaptive neuro-fuzzy inference system (ANFIS) can also be alternatives to predict the data with a better level of correlation [75]. 6. Conclusion In this study, glass fibers were used as a modifier in asphalt mixtures containing high contents of RAP material to compensate for the adverse effect of RAP material on cracking performance of the mixtures. For this purpose, different percentages of glass fibers were used as an additive in the asphalt mixtures containing different percentages of RAP material, and the SCB fracture tests were conducted at temperatures of 15, 0 and 15 °C. The results indicated that the positive effect of glass fibers on cracking performance of the recycled mixtures can compensate for the adverse impact of RAP material on the cracking behavior of the recycled mixtures, and the fracture energy of fiber-reinforced recycled mixtures was eider better than or similar to that of the control mix in most cases. However, more investigations about other aspects of the fiber-reinforced recycled asphalt mixtures such as fatigue and mode II fracture performance are needed in future studies. Other tentative conclusions are listed as follows: From the fracture test results of virgin asphalt mixtures, using up to 0.12% of glass fiber resulted in a significant improvement in the crack resistance of asphalt mixtures. Adding more fibers declined the cracking performance of the mixtures. However, the mixtures containing 0.18% fiber still performed better than the control mixture in terms of crack resistance. At the temperature of 15 °C, the fracture performance improved by increasing the RAP content and glass fibers due to the increase in stiffness of the mixtures. At temperatures of 0 and 15 °C, the crack resistance of the mixtures reduced by increasing the RAP content. The decline was reversible to a great extent when 0.12% of glass fiber was used as an additive in the mixtures. The fracture energy of the SCB specimens with 25 mm notch lengths was in a fair agreement with the Jc results at all temperatures. A regression model with a fair level of correlation was fitted on the results of fracture energy until failure and Jc values.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References [1] H. Ziari, A. Moniri, N. Norouzi, The effect of nanoclay as bitumen modifier on rutting performance of asphalt mixtures containing high content of rejuvenated reclaimed asphalt pavement, Pet. Sci. Technol. (2019) 1–6, https://doi.org/10.1080/10916466.2018.1471489. [2] M.J. Ayazi, A. Moniri, P. Barghabany, Moisture susceptibility of warm mixedreclaimed asphalt pavement containing Sasobit and Zycotherm additives, Pet. Sci. Technol. 35 (9) (2017) 890–895. [3] H. Behbahani, M.J. Ayazi, A. Moniri, Laboratory investigation of rutting performance of warm mix asphalt containing high content of reclaimed asphalt pavement, Pet. Sci. Technol. 35 (15) (2017) 1556–1561. [4] H. Ziari, A. Moniri, M.J. Ayazi, M. Nakhaei, Investigation of rutting performance of wma mixtures containing copper slag, Int. J. Transport. Eng. 3 (3) (2016) 227–235. [5] M. Fakhri, A.R. Ghanizadeh, An experimental study on the effect of loading history parameters on the resilient modulus of conventional and SBS-modified asphalt mixes, Constr. Build. Mater. 53 (2014) 284–293. [6] H. Haghshenas, H. Nabizadeh, Y.-R. Kim, and K. Santosh, ‘‘Research on high-rap asphalt mixtures with rejuvenators and WMA additives,” 2016.
9
[7] N.H. Tran, A. Taylor, R. Willis, ‘‘Effect of rejuvenator on performance properties of HMA mixtures with high RAP and RAS contents,” NCAT Report, pp. 12–05, 2012. [8] R.B. Mallick, K.A. O’Sullivan, M. Tao, R. Frank, ‘‘Why not use rejuvenator for 100% RAP recycling?,” 2010. [9] X. Shu, B. Huang, and D. Vukosavljevic, ‘‘Evaluation of cracking resistance of recycled asphalt mixture using semi-circular bending test,” in Paving Materials and Pavement Analysis, 2010, pp. 58–65. [10] J.R. Willis, P. Turner, G. Julian, A.J. Taylor, N. Tran, F. Padula, ‘‘Effects of changing virgin binder grade and content on RAP mixture properties,” NCAT Report, no. 12-03, 2012. [11] W. Mogawer, T. Bennert, J.S. Daniel, R. Bonaquist, A. Austerman, A. Booshehrian, Performance characteristics of plant produced high RAP mixtures, Road Mater. Pav. Design 13 (sup1) (2012) 183–208. [12] H. Ozer, I.L. Al-Qadi, P. Singhvi, T. Khan, J. Rivera-Perez, A. El-Khatib, Fracture characterization of asphalt mixtures with high recycled content using Illinois semicircular bending test method and flexibility index, Transp. Res. Rec. 2575 (1) (2016) 130–137. [13] Z. Zhou, X. Gu, F. Ni, Q. Li, X. Ma, Cracking resistance characterization of asphalt concrete containing reclaimed asphalt pavement at intermediate temperatures, Transp. Res. Rec. 2633 (1) (2017) 46–57. [14] M. Zaumanis, R.B. Mallick, Review of very high-content reclaimed asphalt use in plant-produced pavements: state of the art, Int. J. Pavement Eng. 16 (1) (2015) 39–55. [15] M. Ameri, A. Mansourkhaki, D. Daryaee, Evaluation of fatigue behavior of asphalt binders containing reclaimed asphalt binder using simplified viscoelastic continuum damage approach, Constr. Build. Mater. 202 (2019) 374–386. [16] A. Mansourkhaki, M. Ameri, D. Daryaee, Application of different modifiers for improvement of chemical characterization and physical-rheological parameters of reclaimed asphalt binder, Constr. Build. Mater. 203 (2019) 83–94. [17] T.B. Moghaddam, H. Baaj, The use of rejuvenating agents in production of recycled hot mix asphalt: a systematic review, Constr. Build. Mater. 114 (2016) 805–816. [18] Z. Zhou, X. Gu, Q. Dong, F. Ni, Y. Jiang, Rutting and fatigue cracking performance of SBS-RAP blended binders with a rejuvenator, Constr. Build. Mater. 203 (2019) 294–303. [19] M. Zaumanis, R.B. Mallick, L. Poulikakos, R. Frank, Influence of six rejuvenators on the performance properties of Reclaimed Asphalt Pavement (RAP) binder and 100% recycled asphalt mixtures, Constr. Build. Mater. 71 (2014) 538–550. [20] M. Zaumanis, R.B. Mallick, R. Frank, Evaluation of different recycling agents for restoring aged asphalt binder and performance of 100% recycled asphalt, Mater. Struct. 48 (8) (2015) 2475–2488. [21] S. Kodippily, G. Holleran, T.F. Henning, Deformation and cracking performance of recycled asphalt paving mixes containing polymer-modified binder, Road Mater. Pavement Design 18 (2) (2017) 425–439. [22] Z. Zhou, X. Gu, Q. Li, F. Ni, R. Yuan, Use of rejuvenator, styrene-butadiene rubber latex, and warm-mix asphalt technology to achieve conventional mixture performance with 50% reclaimed asphalt pavement, Transport. Res. Rec. J. Transp. Res. Board 2575 (2016) 160–167. [23] R. S. McDaniel, Fiber additives in asphalt mixtures (no. Project 20-05 (Topic 45-15)). 2015. [24] Z. Dehghan, A. Modarres, Evaluating the fatigue properties of hot mix asphalt reinforced by recycled PET fibers using 4-point bending test, Constr. Build. Mater. 139 (2017) 384–393, https://doi.org/10.1016/ j.conbuildmat.2017.02.082. [25] P. Park, S. El-Tawil, S.-Y. Park, A.E. Naaman, Cracking resistance of fiber reinforced asphalt concrete at 20°C, Constr. Build. Mater. 81 (2015) 47–57, https://doi.org/10.1016/j.conbuildmat.2015.02.005. [26] S.M. Abtahi, M. Sheikhzadeh, S.M. Hejazi, Fiber-reinforced asphalt-concrete–a review, Constr. Build. Mater. 24 (6) (2010) 871–877. [27] X. Qin, A. Shen, Y. Guo, Z. Li, Z. Lv, Characterization of asphalt mastics reinforced with basalt fibers, Constr. Build. Mater. 159 (2018) 508–516. [28] A. Mansourian, A. Razmi, M. Razavi, Evaluation of fracture resistance of warm mix asphalt containing jute fibers, Constr. Build. Mater. 117 (2016) 37–46. [29] C.J. Slebi-Acevedo, P. Lastra-González, P. Pascual-Muñoz, D. Castro-Fresno, Mechanical performance of fibers in hot mix asphalt: a review, Constr. Build. Mater. 200 (2019) 756–769. [30] F. Morea, R. Zerbino, Improvement of asphalt mixture performance with glass macro-fibers, Constr. Build. Mater. 164 (2018) 113–120. [31] A. Najd, Z. Chao, G. Ying, Experiments of fracture behavior of glass fiber reinforced asphalt concrete, J. Chang’an Univers. (Nat. Sci. Ed.) 25 (3) (2005). [32] S.H. Khanghahi, A. Tortum, Determination of the optimum conditions for gilsonite and glass fiber in HMA under Mixed Mode I/III loading in fracture tests, J. Mater. Civ. Eng. 30 (7) (2018) 04018130. [33] M. Enieb, A. Diab, X. Yang, Short-and long-term properties of glass fiber reinforced asphalt mixtures, Int. J. Pavement Eng. (2019) 1–13. [34] M. Aliha, H. Fattahi Amirdehi, Fracture toughness prediction using Weibull statistical method for asphalt mixtures containing different air void contents, Fatigue Fract. Eng. Mater. Struct. 40 (1) (2017) 55–68. [35] M. Sabouri, D. Mirzaeian, A. Moniri, Effectiveness of linear amplitude sweep (LAS) asphalt binder test in predicting asphalt mixtures fatigue performance, Constr. Build. Mater. 171 (2018) 281–290.
10
H. Ziari et al. / Construction and Building Materials 230 (2020) 117015
[36] M. Fakhri, E.H. Kharrazi, M. Aliha, Mixed mode tensile–In plane shear fracture energy determination for hot mix asphalt mixtures under intermediate temperature conditions, Eng. Fract. Mech. 192 (2018) 98–113. [37] M.R.M. Aliha, H. Behbahani, H. Fazaeli, M.H. Rezaifar, Study of characteristic specification on mixed mode fracture toughness of asphalt mixtures, Constr. Build. Mater. 54 (2014/03/15/ 2014,) 623–635, https://doi.org/10.1016/ j.conbuildmat.2013.12.097. [38] M. Aliha, H. Fazaeli, S. Aghajani, F.M. Nejad, Effect of temperature and air void on mixed mode fracture toughness of modified asphalt mixtures, Constr. Build. Mater. 95 (2015) 545–555. [39] M. Aliha, M. Sarbijan, Effects of loading, geometry and material properties on fracture parameters of a pavement containing top-down and bottom-up cracks, Eng. Fract. Mech. 166 (2016) 182–197. [40] M.R.M. Aliha, A. Bahmani, S. Akhondi, A novel test specimen for investigating the mixed mode I+III fracture toughness of hot mix asphalt composites – Experimental and theoretical study, Int. J. Solids Struct. 90 (2016) 167–177, https://doi.org/10.1016/j.ijsolstr.2016.03.018. [41] P.J. Haghighat Pour, M.R.M. Aliha, M.R. Keymanesh, Evaluating mode I fracture resistance in asphalt mixtures using edge notched disc bend ENDB specimen with different geometrical and environmental conditions, Eng. Fract. Mech. 190 (2018) 245–258, https://doi.org/10.1016/j.engfracmech.2017.11.007. [42] M. Ameri, S. Nowbakht, M. Molayem, M. Aliha, Investigation of fatigue and fracture properties of asphalt mixtures modified with carbon nanotubes, Fatigue Fract. Eng. Mater. Struct. 39 (7) (2016) 896–906. [43] G. Saha, K.P. Biligiri, Fracture properties of asphalt mixtures using semicircular bending test: a state-of-the-art review and future research, Constr. Build. Mater. 105 (2016) 103–112. [44] M. Aliha, M. Fakhri, E.H. Kharrazi, F. Berto, The effect of loading rate on fracture energy of asphalt mixture at intermediate temperatures and under different loading modes, Frattura ed Integrità Strutturale 12 (43) (2018) 113–132. [45] M. Aliha, H. Behbahani, H. Fazaeli, M. Rezaifar, Study of characteristic specification on mixed mode fracture toughness of asphalt mixtures, Constr. Build. Mater. 54 (2014) 623–635. [46] M. Ameri, A. Mansourian, M. Heidary Khavas, M. Aliha, M. Ayatollahi, Cracked asphalt pavement under traffic loading–A 3D finite element analysis, Eng. Fract. Mech. 78 (8) (2011) 1817–1826. [47] M. Ameri, A. Mansourian, S. Pirmohammad, M. Aliha, M. Ayatollahi, Mixed mode fracture resistance of asphalt concrete mixtures, Eng. Fract. Mech. 93 (2012) 153–167. [48] T. Tam, A. Bhatnagar, 1 – High-performance ballistic fibers and tapes, in: Lightweight Ballistic Composites, Second Edition., Woodhead Publishing, Bhatnagar Ed., 2016, pp. 1–39. [49] A.D/DM-17, Standard Test Methods for Quantitative Extraction of Asphalt Binder from Asphalt Mixtures, ASTM International, West Conshohocken, PA, 2017. [50] H. Ziari, A. Moniri, P. Bahri, Y. Saghafi, The effect of rejuvenators on the aging resistance of recycled asphalt mixtures, Constr. Build. Mater. 224 (2019) 89– 98. [51] A.D/DM-12, Standard practice for recovery of asphalt from solution using the rotary evaporator, ASTM International, West Conshohocken, 2012. [52] M. Zaumanis, R.B. Mallick, R. Frank, Determining optimum rejuvenator dose for asphalt recycling based on Superpave performance grade specifications, Constr. Build. Mater. 69 (2014) 159–166. [53] A.D. T245, Standard Method of Test for Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus, AASHTO, Washington, DC, 2004. [54] D. ASTM, ‘‘3515, Standard Specification for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures,” Annual Book of Standards, vol. 4, 2004. [55] Hassan Ziari, Ali Moniri, Reza Imaninasab, Mostafa Nakhaei, Effect of copper slag on performance of warm mix asphalt, Int. J. Pavement Eng. 20 (7) (2019) 775–781, https://doi.org/10.1080/10298436.2017.1339884.
[56] H. Ziari, M. Nakhaei, A. Akbari Nasrekani, A. Moniri, Characterization of rutting resistance of EBS-modified asphalt mixtures, Pet. Sci. Technol. 34 (13) (2016) 1107–1112. [57] A.H. Korayem, H. Ziari, M. Hajiloo, A. Moniri, Rutting and fatigue performance of asphalt mixtures containing amorphous carbon as filler and binder modifier, Constr. Build. Mater. 188 (2018) 905–914. [58] A. Standard, ‘‘D8044-16: Standard Test Method for Evaluation of Asphalt Mixture Cracking Resistance using the Semi-Circular Bend Test (SCB) at Intermediate Temperatures.,” Book of Standards, vol. 4, 2016. [59] H.R. Fattahi Amirdehi, M.R.M. Aliha, A. Moniri, A.R. Torabi, Using the generalized maximum tangential stress criterion to predict mode II fracture of hot mix asphalt in terms of mode I results – A statistical analysis, Constr. Build. Mater. 213 (2019) 483–491, https://doi.org/10.1016/ j.conbuildmat.2019.04.067. [60] M. Ayatollahi, M. Aliha, Wide range data for crack tip parameters in two disctype specimens under mixed mode loading, Comput. Mater. Sci. 38 (4) (2007) 660–670. [61] G. Saha, K.P. Biligiri, Fracture damage evaluation of asphalt mixtures using Semi-Circular Bending test based on fracture energy approach, Eng. Fract. Mech. 142 (2015) 154–169. [62] M. Minhajuddin, G. Saha, K.P. Biligiri, Crack propagation parametric assessment of modified asphalt mixtures using linear elastic fracture mechanics approach, J. Test. Eval. 44 (1) (2015) 471–483. [63] M. Kuruppu, Y. Obara, M. Ayatollahi, K. Chong, T. Funatsu, ISRM-suggested method for determining the mode I static fracture toughness using semicircular bend specimen, Rock Mech. Rock Eng. 47 (1) (2014) 267–274. [64] H. Ziari, A. Moniri, Laboratory evaluation of the effect of synthetic Polyolefinglass fibers on performance properties of hot mix asphalt, Constr. Build. Mater. 213 (2019) 459–468, https://doi.org/10.1016/j.conbuildmat.2019.04.084. [65] H. Jahanbakhsh, P. Hosseini, F.M. Nejad, M. Habibi, Intermediate temperature fracture resistance evaluation of cement emulsified asphalt mortar, Constr. Build. Mater. 197 (2019) 1–11. [66] M. Ling, X. Luo, Y. Chen, S. Hu, R.L. Lytton, A calibrated mechanics-based model for top-down cracking of asphalt pavements, Constr. Build. Mater. 208 (2019) 102–112, https://doi.org/10.1016/j.conbuildmat.2019.02.090. [67] W. Song, B. Huang, X. Shu, Influence of warm-mix asphalt technology and rejuvenator on performance of asphalt mixtures containing 50% reclaimed asphalt pavement, J. Cleaner Prod. 192 (2018) 191–198. [68] X. Luo, Y. Zhang, R.L. Lytton, Implementation of pseudo J-integral based Paris’ law for fatigue cracking in asphalt mixtures and pavements, Mater. Struct. 49 (9) (2016) 3713–3732. [69] Z. Wu, L.N. Mohammad, L. Wang, M.A. Mull, Fracture resistance characterization of superpave mixtures using the semi-circular bending test, J. ASTM Int. 2 (3) (2005) 1–15. [70] H. Kuai, H. Lee, G. Zi, S. Mun, Application of generalized J-integral to crack propagation modeling of asphalt concrete under repeated loading, Transp. Res. Rec. J. Transp. Res. Board 2127 (2009) 72–81. [71] Y.-R. Kim, J. Zhang, H. Ban, Moisture damage characterization of warm-mix asphalt mixtures based on laboratory-field evaluation, Constr. Build. Mater. 31 (2012) 204–211. [72] L.N. Mohammad, M. Kim, M. Elseifi, Characterization of asphalt mixture’s fracture resistance using the semi-circular bending (SCB) test, in: 7th RILEM International Conference on Cracking in Pavements, Springer, 2012, pp. 1–10. [73] K.P. Biligiri, S. Said, H. Hakim, Asphalt mixtures, Int. J. Pavement Res. Technol. 5 (4) (2012) 209–217. [74] H. Fazaeli, Y. Samin, A. Pirnoun, A.S. Dabiri, Laboratory and field evaluation of the warm fiber reinforced high performance asphalt mixtures (case study Karaj-Chaloos Road), Constr. Build. Mater. 122 (2016) 273–283. [75] H. Ziari, A. Amini, A. Goli, D. Mirzaiyan, Predicting rutting performance of carbon nano tube (CNT) asphalt binders using regression models and neural networks, Constr. Build. Mater. 160 (2018) 415–426.