Egyptian Journal of Petroleum (2012) 21, 149–154

Egyptian Petroleum Research Institute

Egyptian Journal of Petroleum

www.elsevier.com/locate/egyjpwww.sciencedirect.com

FULL LENGTH ARTICLE

The addition effects of macro and nano clay

on the performance of asphalt binder

M. El-Shafie, I.M. Ibrahim, A.M.M. Abd El Rahman *

Egyptian Petroleum Research Institute (EPRI), Nasr City, Cairo, Egypt

Received 23 January 2012; accepted 23 April 2012

Available online 29 January 2013

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KEYWORDS

Macroclay;

Nanoclay;

Modified asphalt;

Nano-modification;

Characterization

Corresponding author. Tel.:+mail address: dr.amaepri@y

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Abstract The study was carried out to explore the addition effect of macro and organically mod-

ified nanoclay on the physical and mechanical properties of asphalt binders. Both macroclay and

modified nanoclay were blended in an asphalt binder in various percentages (starting from 2%

to 8%). The blended asphalt binders were characterized using kinematic viscosity (C.st), softening

point (�C), and penetration and compared with anunmodified binder. The tensile strength of the

asphalt binders was also tested as a function of clay types and content%. The results of the study

indicated an increase in softening point; kinematics viscosity and decrease in binder penetration.

The tensile strength of modified clay binders was enhanced at all percentages by a comparison with

both macroclay and unmodified binders. The best improvements in the modified binders were

obtained with 6% nanoclay.ª 2013 Egyptian Petroleum Research Institute. Production and hosting by Elsevier B.V.

All rights reserved.

1. Introduction

Asphalt has been widely used as a binder in the construction ofhighways and runways for a long time due to its good visco-elastic properties [1]. Bitumen is an organic mixture composed

of various chemical compounds. The physical properties andchemical structures of asphalts will be changed when exposedto heat, oxygen, and ultraviolet (UV) light, which is called

aging [2–4]. So the ideal asphalt [5] should possess both: (1)

45902; fax: +202 22747433.(A.M.M. Abd El Rahman).

gyptian Petroleum Research

g by Elsevier

esearch Institute. Production and

008

high relative stiffness at high service temperatures (summer)

to reduce rutting and shoving and; (2) increased adhesion be-tween the asphalt and aggregate in the presence of moistureto reduce stripping.

The incorporation of nanoparticles into polymer systems

can be expected to enhance their performance because of theirproperties, including their high surface-to-volume ratio, andwith the consequence that much lower loadings are required

to achieve equivalent properties, compared to conventional,microscale composites [6,7]. Hanyu et al. [8], Chen and Huang[9], Fu et al. [10], and Yildirim [11] have used nanoclays as a

secondary modifier to further enhance the performance prop-erties of styrene–butadiene–styrene (SBS) copolymer modifiedasphalt by adding the sodium montmorillonite (Na-MMT)

and organophilic montmorillonite (OMMT) nanoclays, itwas found that: (1) the viscosity of the SBS-modified asphaltwas increased; (2) the stiffness (complex modulus) was in-

hosting by Elsevier B.V. All rights reserved.

150 M. El-Shafie et al.

creased while the phase angle decreased. The research resultsare an indication that the Na-MMT and OMMT nanoclayshave promising potential to reduce the permanent deformation

or rutting of asphalt pavements. Yu et al. [12], and Yu et al.[13] have detected that Na-MMT and OMMT form an interca-lated and exfoliated structure within the SBS copolymer mod-

ified asphalt binder system. Roy et al. [14,15] enhanced thecompressive and shear strength of thermoplastic polymersusing only a small weight percent of nanoclay reinforcement.

It has been found that physical properties, rheological behav-iors of bitumen and polymer modified bitumen could be obvi-ously improved due to the introduction of OMMT. When thepolymer penetrates between the adjacent layers of the nanoclay

[16], the gallery spacing is increased and the resulting morphol-ogy is an intercalated structure. Researchers suggested thatnanoclay modifications improve some characteristics of as-

phalt binders and asphalt mixtures, but more research is re-quired before it can be applied on a large scale.

2. Materials and experimental procedures

2.1. Materials

Asphalt: Local asphalt of penetration grade 60/70, pro-duced by El-Nasser Petroleum Company Suez – Egyptwas used. Its physical properties and chemical constituents

are shown in Table 1.Organo clay: Local organoclay taken from SPREA MISRCo. 10 of Ramadan city.

Intercalating agent (Surfactant): Cetyltrimethylammoniumbromide (CTAB) purchased from an Indian supplier of lab-oratory chemicals in Delhi, India.

2.2. Experimental procedures

2.2.1. Preparation of asphalt binder with macroclay

The required amount of the base asphalt was heated to 140 �Cand stirred for about 5 min, the temperature was raised to

160 �C then four percentages of macroclay (2%, 4%, 6%,and 8% by weight) were added slowly to the base asphalt withcontinuous stirring at 160 �C for two hours until it achieves a

Table 1 Physical properties and chemical constituents of

asphalt cement 60/70.

Properties Values

Physical properties

Penetration at 25 �C 100 g, 5 s, 0.1 mm 64

Kinematics viscosity at 135 �C, C.st 355

Absolute viscosity at 60 �C, poise 250

Flash point, �C (Clevel and open cup) 120

Ductility at 25 �C, 5 cm/min, cm 52

Softening point �C (Ring and Ball) 99.9

Solubility in trichloroethylene, %

Chemical constituents, wt%

Oils % 27.8

Resins % 48.6

Asphaltens % 23.6

completely homogenous asphalt blend to produce B1, B2, B3

and B4 respectively.

2.2.2. Treatment of clay (Na+–MMT)

Organoclay (OMMT) was prepared [17] by a cationic ex-change process in an aqueous solution by vigorously stirring25 g Na+–MMT dispersed in 800 ml of distilled water at

80 �C with 10 g cetyltrimethylammonium bromide for 2 h.The precipitate was filtered and washed several times withwarm distilled water until no chloride ions were detected with

0.1 N AgNO3 solution. It was then dried at 60 �C for 24 h. Theorganophilic montmorillonite was ground with a mortar andparticles of size less than 75 lm were collected for the prepara-

tion of nanocomposites.

2.2.3. Preparation of asphalt nanocomposite [18]

The asphalt nanocomposite was prepared using a high-shear

mixer. The asphalt was first heated to 160 �C to a fluid stateand the surfactant-modified nanoclay, (2%, 4%, 6%, and8 wt%) was added to the system and mixed at 2500 rpm for

3 h to disperse the intercalated OMMT nanoclay. And finallycompletely homogenous asphalt blends are obtained to pro-duce B5, B6, B7 and B8 respectively. All the prepared binders

from B1 to B8 were left to cool at room temperature.

2.3. Testing procedures

The principal test methods on the modified blends of the as-

phalt binder and unmodified asphalt are:

2.3.1. Physical properties

Penetration test at 25 �C according to ASTM D5-97, Softeningpoint (Ring and Ball) according to ASTM D36-95, and Kine-matic viscosity (C.st) at 135 and 150 �C, according to ASTMD-2170, were carried out.

2.3.2. Mechanical properties

Tensile strength test according to ASTMD-5147 (by using Shi-madzu Universal Testing Machine with computer controlled

hydraulic servo system velocity 20 mm/min) was carried outon all modified and unmodified asphalts at �7 �C and 25 �C.The specimen is 100 mm in overall length, including the end in-

2 4 6 8 10

Inte

nis

ty

0

200

400

600

800

1000

1200

1400

Clay Organo clay

d=1.26 nmd=2.42 nm

2θ (degree)

Figure 1 XRD of both macroclay and modified nanoclay.

0

200

400

600

800

1000

1200

1400

Polymer content %

Kin

emat

ic v

isco

sity

, C.s

t

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Figure 2 Effect of clay content on kinematic viscosity at 150 �C.

0

100

200

300

400

500

600

700

Polymer content %

Kin

emat

ic v

isco

sity

, C.s

t

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Figure 3 Effect of clay content on kinematic viscosity at 135 �C.

0

10

20

30

40

50

60

70

80

Polymer content %

soft

enin

g te

mpe

ratu

re °

C

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Figure 4 Effect of clay content on penetration value.

The addition effects of macro and nano clayon the performance of asphalt binder 151

serts. The end inserts are each 30 mm long by 20 mm wide. Theasphalt portion of the specimen is 40 mm long with an effective

gauge length of 27 mm and cross-sectional dimensions of 6 mmwide by 6 mm thick. Failure stress and strain were computedaccording to the following equations:r = P/Awhere r is the

failure stress (N/mm2); P, failure load (N); and A, original areaof cross section (mm2).e = d/Lwhere e is the failure strain(mm/mm); and d, elongation at failure.

3. Results and discussion

3.1. X-ray diffraction

Both macroclay and modified nanoclay were examined withXRD technique as shown in Fig. 1. By comparing the X-ray

Table 2 Effect of clay content on physical properties of asphalt cem

Binder

No.

Clay content

(%)

Penetration

0.1 mm

Softening

temperatur

Control 0 64 52

B1 2 60 54

B2 4 57 57

B3 6 52 59

B4 8 51 60

diffractograms of macroclay and modified nanoclay, it wasfound that a strong shift in the position of 2h planes (2h chan-

ged from 7.01–3.63�) took place, that means an increase in thebasal spacing of these planes. The increase was relatively large,from 1.26–2.42 nm that confirms the occurrence of organicmolecule intercalation between silicate platelets.

3.2. Kinematic viscosity

Figs. 2 and 3 and Tables 2 and 3 showed that by the addition

of 2% to 8% of macroclay at 135 �C, the viscosity increased byan average 74% and 140% for B1–B4 respectively. On theother hand by using nanoclay of 2% and 8%, the viscosity in-

creased by an average 140–236% for B5–B8 respectively com-pared with the unmodified binder. At 150 �C the kinematicviscosity increased by an average of 45% and 102% for B1–

B4 (asphalt with 2% and 8% unmodified clay) respectivelycompared with the unmodified binder, while, it was rangingfrom 94% to 160% for B5 and B8 (asphalt with 2% and 8%modified clay) respectively. The maximum increment was

found with 8% of nanoclay compared to unmodified binders.The increase in the viscosity value at high temperature is agood property of rutting resistance [19].

3.3. Softening point temperature

Asphalt with unmodified macroclay gives a higher softening

temperature compared with unmodified asphalt by an average2–8 �C for B1 and B4 respectively as shown in Fig. 4. While,asphalt modified nanoclay composite gives a higher softeningtemperature by an average 4–13 �C for B5 and B8 (modified

clay with asphalt) respectively compared with the unmodified

ent 60/70.

e (�C)Kinematic viscosity at

135 �C (C.st)

Kinematic viscosity at

150 �C (C.st)

355 211

618 306

690 348

816 381

851 426

0

10

20

30

40

50

60

70

80

Polymer content %

Pene

trat

ion

0.1m

m

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Figure 5 Effect of clay content on softening temperature.

Table 3 Effect of modified clay content on physical properties of asphalt cement 60/70.

Binder

No.

Modified clay

content (%)

Penetration

0.1 mm

Softening

temperature (�C)Kinematic viscosity at

135 �C (C.st)

Kinematic viscosity at

150 �C (C.st)

Control 0 64 52 355 211

B5 2 55 56 853 410

B6 4 52 60 941 463

B7 6 48 64 1143 518

B8 8 46 65 1195 550

152 M. El-Shafie et al.

binder. The effect of modified the modified asphalts are lesssensitive to high temperature changes and may also be moreresistant to plastic deformation (rutting) compared to unmod-ified asphalt in Table 3.

Table 4 Effect of unmodified and modified clay on tensile strength

Unmodified clay

Binder

No.

Clay content

(%)

Tensile strength

Tensile stress

(MPa)

Tensile strain

(mm)

Control 0 0.78 209

B1 2 1.23 239

B2 4 1.52 258

B3 6 1.75 286

B4 8 1.83 298

Table 5 Effect of modified and unmodified clay on tensile strength

Unmodified clay

Binder

No.

Clay content

(%)

Tensile strength

Tensile stress

(MPa)

Tensile strain

(mm)

Control 0 0.26 520

B1 2 0.54 413

B2 4 0.69 382

B3 6 0.88 366

B4 8 0.93 359

3.4. Penetration test

Fig. 5 showed that the penetration value was decreased for allmodified binders (macroclay and modified nanoclay) at 25 �Ccompared with the unmodified binder as shown in Fig. 5. The

decrease in the penetration value for asphalt with macroclayranged from 7% to 20% for B1 and B4 (asphalt with unmod-ified clay) respectively, while, it rangedfrom 14% to 28% for

B5 and B8 (asphalt with modified nanoclay) respectively com-pared with the unmodified binder. The maximum decrease inthe penetration value was recorded with 8% nanoclay contents

for all modified compared with the control binder; since thereis no significant difference between 6% and 8% nanoclay con-tent, and from the practical cost view the ratio of 6% of nano-

clay content was applied to be the most suitable ratio fornanoclay addition.

3.5. Tensile strength test

The effect of the addition of macroclay and modified nanoclayon the tensile strength at �7 �C and 25 �C is shown in Tables 4and 5 and Figs. 6–9.

of asphalt binder 60/70 at �7 �C.

Modified clay

Binder

No.

Modified clay

content (%)

Tensile strength

Tensile stress

(MPa)

Tensile strain

(mm)

Control 0 0.78 209

B5 2 1.68 250

B6 4 1.89 265

B7 6 2.18 294

B8 8 2.26 312

of asphalt binder 60/70 at 25 �C.

Modified clay

Binder

No.

Modified Clay

content (%)

Tensile strength

Tensile stress

(MPa)

Tensile strain

(mm)

Control 0 0.26 520

B5 2 0.8 396

B6 4 0.93 363

B7 6 1.22 338

B8 8 1.25 326

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Polymer content %

Ten

sile

str

ess

MPa

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Figure 6 Effect of clay content on tensile stress at 25 �C.

0

50

100

150

200

250

300

350

400

450

500

550

600

Polymer content %

Ten

sile

str

ain,

mm

.

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Figure 7 Effect of clay content on tensile strain at 25 �C.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

Ten

sile

str

ess

MPa

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Polymer content %

Figure 8 Effect of clay content on tensile stress at �7 �C.

0

50

100

150

200

250

300

350

400

Polymer content %

Ten

sile

str

ain,

mm

.

Control

Asphalt+Clay

Asphalt+Modified clay

82 640

Figure 9 Effect of clay content on tensile strain at �7 �C.

The addition effects of macro and nano clayon the performance of asphalt binder 153

d The tensile stress values for all modified binders wereincreased with increasing clay content up to 8% comparedwith the control binder, while, the strain values for all mod-ified binders were decreased with increasing polymer con-

tent up to 8% as compared with the control binder. Thisis because the unmodified asphalt binder is more sensitiveto temperature changes as proved by softening temperature

and viscosity. The increase in stress value at �7 �C rangedfrom about 58–124% for B1 and B3 (asphalt with 2% and

6% unmodified clay) respectively compared with the con-trol binder. Also increasing unmodified macroclay from6% to 8% the tensile stress value was slightly increased to

about 11%, while, the increase percent in strain values ran-ged from about 14–37% for B1 and B3 respectively com-pared with the control binder. When unmodified clay

percent increased from 6% to 8% the strain value wasslightly increased by about 6% for the same sample.

d Asphalt binders B5 and B7 that contain modified nanoclay

(2% and 6%) have stress values at �7 �C ranging fromabout 115–179% as compared with the control binder,and also when the amount of modified clay increased from6% to 8% the stress value was slightly increased by about

11%, while, the increase in strain values ranged from about20–41% for the same binders.

d The same behaviors were noticed when the temperature was

increased to 25 �C with one exception that the maximumstrain percent of the base binder was higher than 520%than all examined asphalt binders. Asphalt binders B1 and

B3 that contain unmodified clay with 2% and 6% havestress values that ranged from about 107–238% respectivelyas compared with the control binder. When unmodified clay

percent increased from 6% to 8% the stress value wasslightly increased to about 19%, while, the decrease percentin strain values ranged from about 21–29% for B1 and B3

respectively. When the unmodified clay percent increased

from 6% to 8% the strain value was slightly decreased byabout 2%.

Asphalt binders B5 and B7 that contain 2% and 6% modi-fied nanoclay at 25 �C have stress values of 207% and 370%respectively, also by increasing the amount of modified clay

from 6% to 8% the stress value was slightly increased to about10% as compared with the control binder, while, the decreasepercent in strain values ranged from about 24–35% for B5 andB7 respectively comparing with the control binder. When mod-

ified clay percent increased from 6% to 8% the strain valuewas slightly decreased by about 2%. It is well known thatthe difference between 6% and 8% polymer content is not sig-

nificant. This means that the asphalt binder with modified clayis more resistant to thermal cracking at low temperatures thanthe base asphalt. It is also well known that the increase in

154 M. El-Shafie et al.

strain percent without increasing the stress value is not a goodproperty of resistance to plastic deformation at high trafficload.

4. Conclusion

In this paper macroclay was converted to organically modified

nanoclay and was confirmed by the XRD technique. Since thehigh dispersion [20], the large surface area of nanoscopic levelof clay, and the stiffening behavior of nanoclay as they form

bond chains within the binder, the physical and mechanicalproperties of binders are significantly improved as follows:

Gives a higher softening temperature (increase 12 �C) thanthe base asphalt binders.The decrease in penetration value is 25% compared with

the control binder.Increasing in Kinematic viscosity value at 135 �C by anaverage of 222% compared with the control binder.Increasing in Kinematic viscosity value at 150 �C by an

average of 145% compared with the control binder.The stress value increased by an average of 179% at �7 �C,and about 370% at 25 �C compared with the control

binder.The strain value decreased by an average of 41% at �7 �C,and about 35% at 25 �C compared with the control binder.

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