Evaluation of electric arc furnace steel slag coarse aggregate in warm mix asphalt subjected to long-term aging

Construction and Building Materials 135 (2017) 260–266

Contents lists available at ScienceDirect

Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat

Evaluation of electric arc furnace steel slag coarse aggregate in warm mix asphalt subjected to long-term aging Sajjad Masoudi a,⇑, Sayyed Mahdi Abtahi a, Ahmad Goli b a b

Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran Department of Transportation Engineering, University of Isfahan, Isfahan, Iran

h i g h l i g h t s
Aging indices were defined for evaluation of specimens aging.
The use of EAF steel slag improved tensile strength and resilient modulus.
Moisture resistance of WMAs containing steel slag were similar to HMAs with limestone.
Mixtures containing EAF steel slag showed higher aging.

a r t i c l e

i n f o

Article history: Received 3 May 2016 Received in revised form 18 November 2016 Accepted 29 December 2016

Keywords: Warm mix asphalt Sasobit Steel slag Aging Resilient modulus

a b s t r a c t Considering the sustainable development principle, it seems necessary to reduce the temperature demands in producing asphalt mixtures and to replace mineral aggregates with secondary materials. In this study, the long-term performance of warm mix asphalt containing electric arc furnace steel slag was investigated. For this, Marshall Stability, resilient modulus at 25 °C and 40 °C, indirect tensile strength and moisture susceptibility tests were conducted. In the last stage, the ratio between the results of long-term and short-term aging of these tests was presented as an aging index. Using warm mix asphalt and replacing mineral aggregates with steel slag aggregate cause Marshall Stability, stiffness, resilient modulus and indirect tensile strength to increase. Although the tests conducted in this study indicate that using steel slag results in increased aging of the asphalt mixtures, warm asphalt mixtures containing steel slag experience less aging compared to control specimens (hot mix asphalt with limestone). Therefore, warm asphalt mixtures containing steel slag exhibit enhanced short-term and longterm performance as well as less aging. Hence, utilizing warm mix asphalt containing steel slag is generally recommended. Ó 2017 Elsevier Ltd. All rights reserved.

1. Introduction Transportation significantly contributes to the environmental pollution. Roads and their pavements as indivisible parts of transportation possess the same importance. Strategies to reduce pollution and protect the environment during the production of asphalt mixtures can be classified into the following categories: a) Reducing the temperature of mixing and compacting of asphalt mixtures. b) Replacement of mineral aggregates with by-products.

⇑ Corresponding author. E-mail addresses: [email protected] (S. Masoudi), [email protected] (S.M. Abtahi), [email protected] (A. Goli). http://dx.doi.org/10.1016/j.conbuildmat.2016.12.177 0950-0618/Ó 2017 Elsevier Ltd. All rights reserved.

c) Improving the bearing capacity of asphalt mixtures and thereby reducing road asphalt volumes due to decreases in pavement thickness. d) Use of special additives to improve durability and to extend the life of asphalt pavements. e) Use of recycled products. f) Development of inexhaustible and non-polluting new energy sources. g) Use of renewable natural resources and synthetic adhesive binders as replacements for asphalt binders [1]. Reduced mixing temperature has led to considerable energy conservation in the construction of asphalt pavements as less than 50% of the total energy consumption occurs during mixing and drying aggregates [2]. Warm Mix Asphalt (WMA) technologies can help reduce the temperature of mixing and compacting of asphalt

261

S. Masoudi et al. / Construction and Building Materials 135 (2017) 260–266

mixes. This objective is accomplished by either lowering the viscosity of the asphalt binder or improving the workability of the asphalt mix at temperatures lower than those used to produce traditional Hot Mix Asphalt (HMA) [3]. The sustainability of WMA technology is highlighted by the fact that each 10 °C reduction in asphalt mix production temperature decreases fuel oil consumption by 1 L and CO2 emission by 1 kg per ton, according to world bank estimates [4]. Also, lowering the production temperature allows reducing the energy consumption up to 35% or more depending on the WMA process applied [5] and on how much the temperature is reduced [6]. Hurley and Prowell explained that the aggregate type and its interaction with binder grading as well as the type of warm mix additive are important parameters which influence the performance of WMA [7]. Moreover, the physical properties of coarse and fine aggregates have a significant effect on the performance of pavement [8]. Due to the limited natural resources and decreasing mineral aggregates on the one hand and the large-scale production of steel slag on the other hand (approximately fifty million tons of steel slag is produced per year as a by–product in the world) [9], the use of steel slag as an alternative to mineral aggregate seems reasonable, provided that its use does not have significant negative effect on the performance of asphalt mixtures. Depending on the type of metal and the implementation of manufacturing operation, steel slag is a by-product of steel making process that can be categorized as Electric Arc Furnace (EAF), Basic Oxygen Furnace (BOF) and Blast Furnace (BF). Of these categories, EAF steel slag is the common type used in road construction. Numerous research have been undertaken to investigate the possibility of replacing mineral aggregates by steel slag as well as assessing the effects of this slag on the performance of HMA and WMA mixtures, the results of some of which will be cited in following parts. Kara et al. stated that physical properties of steel slag satisfied the requirements in order to be used in asphaltic mixtures [10], but aggregates should not be completely replaced by steel slag as the asphalt mix with 100% steel slag is highly susceptible to bulking and air voids problems due to its angular shape [11]. The influence of utilization of steel slag as a coarse aggregate on the properties of HMA was investigated by Ahmedzadeh and Sengoz. Their observations indicated that the use of steel slag as a coarse aggregate improved the mechanical properties of asphalt mixtures, but increased the optimum binder percentage [12]. Ameri et al. used steel slag as both a fine and coarse portion of aggregate gradation in HMA mixtures and as coarse portion of aggregate gradation in WMA mixture. Among these mixes, HMA mixtures in which fine aggregate was replaced by steel slag had the lowest resilient modulus and indirect tensile strength. In their study, laboratory tests results indicated that the use of coarse steel slag aggregate in WMA mixture enhanced Marshall Stability, Resilient Modulus (MR), Indirect Tensile Strength (ITS), resistance to moisture damage and resistance to permanent deformation of the mixture and thus they recommended the use of coarse electric arc furnace steel slag aggregate for the production of WMA mixture [13]. Kavussi and Qazizadeh investigated the fatigue behavior of asphalt mixes with different percentages of EAF steel slag (25%, 50%, 75%, 100%, purely steel slag and also limestone as the control sample) as coarse aggregate in both aged and unaged conditions. For this purpose, they used a four-point bending beam fatigue test. Their studies showed that although the inclusion of EAF in mixes improved fatigue life of samples, this parameter did not change appreciably in aged specimens [14]. The long-term performance of asphalt mixes is a very important indicator of their economic and environmental assessments. As the WMA is a relatively new technology, few studies have been con-

ducted on long-term aging of warm mix asphalt mixtures containing EAF steel slag. Therefore, it is important to study their longterm performance in the laboratory to predict the behavior of these mixtures in the field. This research primarily attempts to examine the long-term performance of WMA mixes containing EAF steel slag. Therefore, in this research, limestone and EAF steel slag were used for construction of HMA and WMA specimens, considering the short and long term aging. In the last stage, Marshall, ITS, MR and moisture susceptibility tests were conducted on all specimens and aging indices were reported. 2. Materials and experimental procedures One aggregate gradation with two different aggregates has been used in this research. In the first type, the aggregate gradation is comprised of limestone while in second type, steel slag is used as a coarse aggregate ðP 4:75 mmÞ and limestone as both fine aggregate and filler. Depending on the aggregate and the mixing temperature, four types of asphalt mixtures used in this study are listed in Table 1. The asphalt binder utilized to prepare both HMA and WMA mixtures was a PG 64-22 (60/70 penetration grade) from the refinery of Isfahan. The major properties of this binder are reported in Table 2. Limestone used in this study was obtained from a quarry located in eastern Isfahan while EAF steel slag was produced in Mobarakeh steel complex in Isfahan. Table 3 gives the engineering properties of the aggregates used. Chemical and mineralogical composition of the aggregate plays an important role in the way mixtures behave. For this, the chemical properties of limestone and steel slag were determined via applying XRF (X ray fluorescence) testing method, the results of which are presented in Table 4. As is shown in Fig. 1 the aggregate gradations used in this study was fitted in the median limits of ASTM D3515 [15] specifications for dense asphalt mixtures. 2.1. Sample preparation To construct warm asphalt mixtures, 1.5% sasobit by weight of asphalt binder has been added to the mixtures. To mix the binder Table 1 Properties of asphalt mixtures. Type of mixture

Abbreviation

Mixing temp. (°C)

Compaction temp. (°C)

HMA with limestone as a fine and coarse aggregate HMA with steel slag as a coarse aggregate and limestone as a fine aggregate WMA with limestone as a fine and coarse aggregate WMA with steel slag as a coarse aggregate and limestone as a fine aggregate

HL

155

135

HS

155

135

WL

135

115

WS

135

115

Table 2 Properties of asphalt binder. Test

Standard

Result

Specific gravity @ 25 °C (g/cm3) Penetration @ 25 °C (0.1 mm) Softening point (°C) Ductility @ 25 °C (cm) Flash point (°C) Dynamic viscosity @ 60 °C (P) Kinematic viscosity @ 135 °C (cSt)

ASTM ASTM ASTM ASTM ASTM ASTM ASTM

1.019 64 49.7 100< 311 1840 342

D70 D5 D36 D113 D92 D2171 D2170

262

S. Masoudi et al. / Construction and Building Materials 135 (2017) 260–266

Table 3 The physical properties of the aggregates. Test

Standard

Specific gravity (coarse agg.) Bulk SSD Apparent Specific gravity (fine agg.) Bulk SSD Apparent Specific gravity (filler) Water absorption (%) Sand equivalent (%)

ASTM C127

Limestone agg. Coarse

Steel slag agg. Fine

Filler

Coarse

2.65 2.66 2.69

3.4 3.46 3.57

ASTM C128 2.63 2.65 2.67 ASTM D854 ASTM C127 and C128 ASTM D2419

2.7 0.6

0.8 75

1.3

Table 4 Chemical composition of aggregates. Aggregate type

Oxide content (%)

EAF steel slag Limestone

Al2O3

SiO2

SO3

L.O.I.

CaO

Fe2O3

MgO

K2O

4.15 1.83

17.32 11.41

0.56 0.95

1.03 37.56

39.43 44.7

25.28 0.64

5.72 3.12

0.28 0.39

of asphalt mixture (HMA or WMA), the aging (short term or long term aging) and the type of aggregates (lime stone or slag), the relevant test was carried out on 3 samples which their mean values considered as the result.

Passing percent (%)

100 80 60

2.2.1. Marshall testing The Marshall Stability and flow tests of the asphalt mix for both type of aggregates were carried out at various asphalt concentrations according to ASTM D1559 [18]. Furthermore, Marshall Quotient (MQ) which is the ratio of stability (KN) to flow (mm), and an indicator of the mixture stiffness as well is presented.

40 20 0 0.01

0.1

1

10

100

sieve size (mm) Upper range

Lower range

Fig. 1. Gradation of designated aggregate [15].

and sasobit, asphalt binder was heated to the temperature of 140 °C and then sasobit was added to the binder and mixed by a mechanical mixer with 250 rpm for 10 min. The test results of this mixture which is called modified binder are reported in Tables 5–7. According to AASHTO R35, to apply short-term aging, the uncompacted mixtures were placed in a flat shallow pan with an even thickness of 25 to 50 mm and then these mixtures were placed in a forced draft oven with compaction temperatures for 2 h [16]. Also, half of the HMA and WMA samples were selected to be subjected to long-term aging. For this purpose, the specimens were placed in an oven with 85 °C for 120 h as is stated in AASHTO R 30-02 [17]. 2.2. Testing procedures In all tests of Marshall, resilient modulus (MR), indirect tensile strength (ITS) and moisture susceptibility, depending on the type Table 5 Properties of modified binder. Test

Standard

Result

Penetration @ 25 °C (0.1 mm) Softening point (°C)

ASTM D5 ASTM D36

48.5 62.5

2.2.2. Indirect tensile strength test This test is used to determine the resistance of a mixture to tensile loads and is the key index to investigating the cracking potential of asphalt pavements. Thus, a higher value of ITS shows a higher resistance to tensile loads as well as a lower cracking rate during the service life of the mixture. The rate of loading in this test was 51 mm/min and the test was conducted at 25 °C. 2.2.3. Resilient modulus test Asphalt pavement is a visco-elastic material. Elastic and viscous behaviors of asphalt pavement lead to recoverable and permanent deformations. Nevertheless, if the applied load is small compared to the strength of the asphalt mixture and is repeated for a large number of times, it can be considered as an elastic mixture, since its deformation is almost recoverable. Resilient modulus is the ratio of the repeated axial deviator stress to the recoverable axial strain [19]. The MR test was conducted in accordance with ASTM D4123-11 [20] at both 25 °C and 40 °C for analyzing fatigue and rutting damages, respectively. 2.2.4. Moisture susceptibility test Failure of asphalt mixtures can be categorized into adhesive and cohesive failures. In the presence of water, the failure is due to loss of adhesion caused by the de-bonding of the asphalt film from the aggregate surface which is termed stripping. Water can also affect the cohesive properties of the binder, resulting in a severe reduction in integrity and strength of the mixture [21].

263

S. Masoudi et al. / Construction and Building Materials 135 (2017) 260–266 Table 6 The DSR test results of ordinary and modified binders. Type of binder

Aging state

Temp. (°C)

G⁄ (kPa)

(°) d

G⁄/sin(d)

G⁄  sin(d)

Ordinary binder

Original

64 70 64 70 16 19

1.05 0.470 3.75 1.62 11200 7360

86.4 87.7 81.9 84.4 38.4 40.2

1.05 0.470 3.78 1.62 – –

– – – – 6930 4750

64 70 64 70 16 19

1.67 0.839 2.95 1.33 9500 6450

83.3 84.7 82.4 84.6 37.2 39.7

1.69 0.843 2.98 1.33 – –

– – – – 5740 4120

RTFO RTFO + PAV Modified binder

Original RTFO RTFO + PAV

Table 7 The BBR test results of ordinary and modified binders. Type of binder

Parameter

Ordinary binder

Result

m value Stiffness m value Stiffness

Modified binder

AI ¼

@6 °C

@12 °C

0.3342 52.66 0.3491 68.34

0.3028 125.90 0.3102 139.52

RMRLTA@i RMRSTA@i

ð6Þ

LTA and STA indices express the result of long-term and shortterm aged samples, respectively. All of the other parameters were defined in previous sections. The higher value of the AI indicates the deeper degree of bitumen aging.

3. Results and discussions In order to identify the susceptibility of compacted asphalt mixture to moisture, resilient modulus ratio (RMR) was determined [22]. For each mixture type, six specimens with an air void rate of 7% were prepared. Three specimens were submerged in a water bath at 60°Cfor 24 h and then placed in a water chamber maintained at 25 °C for 1 h. These specimens, called conditioned specimens, were later tested for resilient modulus. The unconditioned samples were placed in water bath maintained at 25 °C for 20 min prior to testing. The resilient modulus ratio was calculated based on the following Eq.

RMRi ¼

MRci MRuci

ð1Þ

where MRc is the average of conditioned specimens’ resilient modulus, MRuc is the average of unconditioned samples’ resilient modulus and i is the temperature of the test which can be 25 °C or 40 °C. RMR was determined for both short and long-term aged samples.

3.1. Marshall testing The properties including optimum binder content (O.B.C) of HMA mixtures are presented in Table 8. The O.B.C of warm mix asphalts was considered the same as for hot mixtures [16,23]. Due to the higher porosity of the EAF steel slag compared to the limestone, the O.B.C of mixes containing steel slag was slightly higher. As is presented in Figs. 2 and 3, WS, HS, WL and HL have the highest Marshall Stability and Marshall Quotient, respectively. Higher angle of internal friction, angularity and bulk specific gravity of EAF steel slag compared to the limestone improve aggregates interlocking of steel slag asphalts. Moreover, the better cohesion of binders modified with sasobit might be the cause of higher stability results of WMAs compared to HMAs. Aging can increase both stability and MQ due to increased stiffness.

2.2.5. Aging index In this paper, aging was evaluated by means of the aging index, defined as the following;

StabilityLTA AI ¼ StabilitySTA

ð2Þ

AI ¼

MQ LTA MQ STA

ð3Þ

AI ¼

ITSLTA ITSSTA

ð4Þ

MRLTA@i MRSTA@i

ð5Þ

AI ¼

20 18 16 14 12 10 8 6 4 2 0

17.3

16.77 14.58

15.51

HL

17.43 15.47

HS

WL

19.73 16.89

WS

Specimen

Fig. 2. Marshall Stability test result.

Table 8 Marshall test results. Mixture type

Air void content (%)

Bulk specific gravity

Marshall Stability (KN)

Flow (mm)

MQ (KN/mm)

VMA (%)

VFA (%)

O.B.C (%)

HL HS

4 4

2.376 2.636

14.58 15.51

3.3 3.5

4.42 4.56

14.9 15.2

73 74

4.75 5.2

264

S. Masoudi et al. / Construction and Building Materials 135 (2017) 260–266

6 5

4.42

4.79

4.56

5.28

4.94

4.83

5.12

5.48

3500 3000

3190 2833

2873

2897 2961

3144 3260

2557

2500

4

2000 3

1500

2

1000

1

500 0

0 HL

HS

WL

HL

WS

HS

1200 1000 800

1234

1184

1332 1141

WS

Fig. 5. Result of resilient modulus test at 25 °C.

Fig. 3. Marshall Quotient values.

1400

WL

Specimen

Specimen

3500

1186

1041

3040

3000 2477

887

2500 716

2657 2771

2503

2962

3110

2107

2000

600

1500

400

1000

200

500

0 HL

HS

WL

0

WS

HL

Specimen

HS

WL

WS

Specimen

Fig. 4. Result of Indirect tensile strength.

Fig. 6. Result of resilient modulus test at 40 °C.

3.2. Indirect tensile strength test 1 0.956

0.95

RMR Value

The ITS test results presented in Fig. 4 indicate that mixtures containing steel slag have higher ITS than the ones constructed completely with limestone. Furthermore, mixtures made by modified binder have higher ITS than the ones created with ordinary binder. This behavior is because of better adhesion of slag than limestone and also better adhesion and cohesion of modified binder with sasobit compared to ordinary binders. Higher ITS indicates lower potential for stripping and better fracture properties for asphalt. Subjecting the WMA and HMA specimens to long term aging may decrease the tensile strength and increase the stiffness. However, hardening of the binder can lead to brittle behavior of the material and could also result in adhesive failure. Therefore, tensile strength of asphalt mixtures may decrease as a result of aging.

0.921

0.973 0.934

0.948 0.923 0.905

0.913

0.9 0.85 0.8 0.75 HL

HS

WL

WS

Specimen Short term aged

Long term aged

Fig. 7. Values of resilient modulus ratio at 25 °C.

3.3. Resilient modulus test

1

0.975

0.987 0.967 0.945

0.95

RMR value

The Resilient Modulus results for both short and long term aged samples of all mixtures at temperatures of 25 °C and 40 °C are presented in Figs. 5 and 6. Higher angularity shape and better interlocking, physical and mechanical properties and also better surface adhesion of EAF steel slag are the most important reasons for higher MR of mixtures containing steel slag. Binder as a cohesive material for aggregates plays an important role in stiffness and the bearing capacity of mixtures. Sasobit, at higher and lower temperatures than its melting point has two substantially different functions. Above this temperature, sasobit reduces the binder viscosity but at lower temperatures forms a lattice structure in the asphalt binder and provides better stability. Formation of this lattice structure prevents the movement of molecules in the modified binder. Consequently, it increases the viscosity and stiffness of samples which in turn leads to an increase in

0.905

0.9

0.888

0.894

0.868

0.85 0.8 0.75 HL

HS

WL

Specimen Short term aged

Long term aged

Fig. 8. Values of resilient modulus ratio at 40 °C.

WS

265

0.890 0.917 0.940 0.925

0.963 0.960 0.980 0.963

1.000

0.880 0.925 0.890

1.176 1.215 1.043 1.050

1.108 1.110 1.022 1.037

0.808

Aging Index

1.200

1.084 1.083 1.093 1.070

1.400

1.150 1.115 1.127 1.168

S. Masoudi et al. / Construction and Building Materials 135 (2017) 260–266

0.800 0.600 0.400 0.200 0.000

HL

HS

WL

WS

Fig. 9. Aging index values.

MR results. Sasobit can simplify the compaction of asphalt mixture. Accordingly, because of the consumption of the same energy for construction of HMA and WMA, mixtures containing sasobit have a lower air void rate. As a result, the stiffness and MR of WMA is more than that of HMA. Aging can change physical, chemical and rheological characteristics of asphalt. Regarding rheological aspects, aging reduces the phase angle and increases the complex modulus ðG Þ. In other words, aging increases the storage modulus and decreases the loss modulus of asphalt which leads to an improvement in strength, viscosity and stiffness which in turn can cause MR enhancement. 3.4. Moisture susceptibility test The resilient modulus ratio for all types of mixtures is presented in Figs. 7and 8 for unaged and aged samples, respectively. As expected, the aggregate source plays an important role in determining the moisture susceptibility of the asphalt pavement. Mixtures containing EAF steel slag as coarse aggregate have better moisture susceptibility than those containing limestone as a fine and coarse aggregate. Also, higher binder content for optimizing the mixes containing steel slag in their lithic skeleton guarantees a thicker film of bitumen covering the grains and therefore more efficient protection against water. WMA specimens have worse moisture susceptibility than HMA specimens which is attributed to the moisture remaining in their aggregates because of lower mixing temperature of WMA mixtures. Furthermore, aging which leads to degrading the adhesion of binder and aggregate aggravates the moisture susceptibility of asphalt mixtures. 3.5. Aging index The aging indices presented in the following allow us to compare the aging of different asphalt mixtures. Also, this figure determines the sensitivity of Marshall Stability, stiffness, resilient modulus and indirect tensile strength to aging. The aging indices that are closer to 1 represent lesser extent of aging (see Fig. 9). The ratio of long-term aging to short-term aging obtained for warm asphalt mixtures is less than that of hot asphalts. The main reason behind this difference may be the presence of fewer voids in warm asphalt mixtures. The major cause of long-term aging is oxidation and thus it can be argued that the presence of fewer voids means less contact between air and bitumen and hence less oxidation and therefore lower aging of warm asphalt mixtures. Another factor affecting the aging index of asphalt is the type of materials. EAF steel slag has a higher thermal capacity than limestone aggregates. Considering the major impact of heat on asphalt

aging, this difference in thermal capacity can be another cause of different aging indices obtained for asphalts made with different materials. 4. Conclusions The present study attempted to investigate the long-term performance of warm asphalt mixtures containing EAF steel slag. Based on the results of laboratory tests, the following conclusions were drawn: - Due to higher porosity and bitumen absorption of steel slag, replacing limestone by this material leads to a 0.45% increase in optimum binder. - WMA mixtures containing EAF steel slag exhibited higher short-term and long-term Marshall Stability, resilient modulus and tensile strength than control samples (HMA with limestone). - Moisture resistance of WMAs containing steel slag was similar to HMAs made with limestone. - Asphalts made with steel slag have a lesser moisture susceptibility than those made with limestone aggregates, while hot asphalts have lower moisture susceptibility than warm asphalts. Both the type of the aggregates and the construction temperature of asphalt play important roles in moisture susceptibility of the resulting asphalt. - The use of steel slag increases the aging index of asphalt mixture. Also, the warm asphalt mixtures have lower aging index than hot asphalts. The type of materials of which asphalt is made affects its aging index.

References [1] A. Jamshidi, M.O. Hamzah, Z. You, Performance of warm mix asphalt containing SasobitÒ: state-of-the-art, Constr. Build. Mater. 38 (2013) 530–553. [2] P. Zapata, J.A. Gambatese, Energy consumption of asphalt and reinforced concrete pavement materials and construction, Infrastruct. Syst. 11 (1) (2005) 9–20. [3] N. Bower, H. Wen, K. Willoughby, J. Westone, J. DeVol, Evaluation of the Performance of Warm Mix Asphalt in Washington State, WSDOT Research Report, WA-RD 789.1, 2012. [4] A. Hanz, H. Bahia, Effects of warm mix additives of mixture workability and the performance implications of reduced binder aging, in: The 7th International Conference and Airfield Pavement Technology, Thailand, 2011, pp. 66–76. [5] J. D’Angelo, E. Harm, J. Bartoszek, G. Baumgardner, M. Corrigan, J. Cowsert, et al., Warm-mix Asphalt: European Practice, FHWA, AASHTO, NCHRP, Alexandria, 2008. Report no. FHWA PL-08-007. [6] J. Button, C. Estakhri, A. Wimsatt, A Synthesis of Warm-Mix Asphalt Report FHWA/TX-07/0-5597-1, Texas Transportation Institute, Texas, 2007. [7] G. Hurley, B. Prowell, Evaluation of Sasobit for Use in Warm-Mix Asphalt, NCAT Report 05–06, Auburn, USA, 2005, pp. 1–30. [8] W.F. Chen, The Civil Engineering Handbook, CRC Press, Florida, 1995.

266

S. Masoudi et al. / Construction and Building Materials 135 (2017) 260–266

[9] H. Motz, J. Geiseler, Products of steel slags an opportunity to save natural resources, Waste Manage. 21 (2002) 285–293. [10] M. Kara, E. Gunay, B. Kavakli, S. Tayfur, K. Eren, G. Karadag, The use of steel slag in asphaltic mixture, Key Eng. Mater. 264–268 (III) (2004) 2493–2496. [11] E.A. Oluwasola, M.R. Hainin, M.M.A. Aziz, Evaluation of asphalt mixtures incorporating electric arc furnace steel slag and copper mine tailings for road construction, Transp. Geotech. 29 (2014), http://dx.doi.org/10.1016/j. trgeo.2014.09.004. [12] P. Ahmedzade, B. Sengoz, Evaluation of steel slag coarse aggregate in hot mix asphalt concrete, J. Hazard. Mater. 165 (2009) 300–305. [13] M. Ameri, S. Hesami, H. Goli, Laboratory evaluation of warm mix asphalt mixtures containing electric arc furnace (EAF) steel slag, Constr. Build. Mater. 49 (2013) 611–617. [14] A. Kavussi, M.J. Qazizadeh, Fatigue characterization of asphalt mixes containing electric arc furnace (EAF) steel slag subjected to long term aging, Constr. Build. Mater. 72 (2014) 158–166. [15] ASTM D3515, Standard Specification for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures, 2001.

[16] R.F. Bonaquist, Mix Design Practices for Warm Mix Asphalt, National Cooperative Highway Research Program, Report 691, 2011. [17] AASHTO R35, Special Mixture Design Considerations and Methods for Warm Mix Asphalt (WMA), 2012. [18] ASTM D 1559, Standard Test Method for Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus, 1989. [19] Y.H. Huang, Pavement Analysis and Design, Prentice Hall, New Jersey, 1993. [20] ASTM D 4123, Standard Test Method for Determining the Resilient Modulus of Bituminous Mixtures by Indirect Tension Test, ASTM International, Philadelphia U.S., 2011. [21] E.T. Hagos, The effect of aging on binder properties of porous asphalt concrete Master of science thesis, Delft University of Technology, Netherlands, 2008. [22] A. Modarres, M. Rahmanzadeh, Application of coal waste powder as filler in hot mix asphalt, Constr. Build. Mater. 66 (2014) 476–483. [23] G. Hurley, B. Prowell, Evaluation of potential processes for use in warm mix asphalt, Assoc. Asphalt Paving Technol. 75 (2006) 41–90.