86400 Batu Pahat, Johor, Malaysia Batu Pahat, Johor, Malaysia

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1 Key Engineering Materials Vols (2014) pp (2014) Trans Tech Publications, Switzerland doi: / Short Term and Long Term Aging Effects of Asphalt Binder Modified with Montmorillonite Mohd Ezree Abdullah 1,a, Kemas Ahmad Zamhari 2,b, Rosnawati Buhari 3,c, Mohd Nafarizal Nayan 4,d, and Mohd Rosli Hainin 5,e 1-3 Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor, Malaysia 4 Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor, Malaysia 5 Faculty of Civil Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia a ezree@uthm.edu.my, b kemas@uthm.edu.my, c rosna@uthm.edu.my, d nafa@utm.my, e mrosli@utm.my Keywords: montmorillonite, modified asphalt binder, rheology, aging Abstract. Nowadays, most of asphalt used in pavement construction is produced from petrochemicals through refining process of crude oil. When evolves with time, asphalt become stiffer and brittle due aging process. In this paper, the rheological effect of short-term and long-term oxidative ageing of asphalt binder modified with montmorillonite () was studied using Superpave rotational viscometer (RV), dynamic shear rheometer (DSR) and Fourier transform infrared (FTIR) instruments. The results indicate the addition of increased the viscosity. Based on dynamic mechanical analysis with DSR, modified binder has a potential to increase rutting and fatigue resistance. In terms of FTIR test, it appears that the chemical bonding had changed in the asphalt binder before and after RTFO and PAV aging which suggest that the additional of could delay the aging process. Introduction Asphalt is traditionally regarded as a colloidal structure. It is a complex mixture composed of several physical phases and comprised of hydrocarbons and polymers. Asphalt is a mixture of organic liquids that are highly viscous, black, sticky, entirely soluble in carbon disulfide, and composed primarily of highly condensed polycyclic aromatic hydrocarbons. It can be divided into the chemical families of saturates, aromatics, resins, asphaltenes. This material has been widely used as a binder of aggregate in road pavement because of its good viscoelastic properties. The destruction of asphalt pavement is mainly due to the aging of asphalt, which contribute reduction of durability and service life of asphalt pavements [1-4]. Basically, asphalt undergoes two substantially different aging processes throughout the service life. The short term aging process occurred during the production of hot mix asphalt (HMA) where the based asphalt is exposed to high temperature and high degree of air surrounding during the mixing process with aggregate. The long term aging process evolves with time where the asphalt is exposed to the environment as in-service pavement at a relatively lower temperature for a long duration. Short and long-term aging are extremely complex phenomena because of numerous factors influencing the rate of aging. Asphalt constitutes only a small but crucial part of any paving mix. It also influences pavement performance at low and high field operating temperatures [5-6]. Due to continuously increasing traffic volumes, axle loads and the effects of temperature cycling, pure asphalt pavements are subjected to stress cracking and rutting. Therefore, under certain circumstances, base asphalt need to be modified with some additive to meet the requirements of local authorities.

2 Key Engineering Materials Vols Recently, the modification of base asphalt with montmorillonite () has gained more interests among researchers because it is environmentally friendly, readily available and its structure and chemistry have been well studied. is a layered silicate consists of a type of mineral which has a 2:1 layered structure with two silica tetrahedron sandwiching an alumina octahedron. The thickness of the layers (platelets) is 1 nm with a large active surface area which can have an intensive interaction between bitumen and depends upon the type of material mixed [3, 7-10]. The proper selection of modified is essential to ensure effective penetration of the asphalt into the interlayer spacing of the and so resulting in the desired exfoliated product. An exfoliated morphology occurs when the platelets are extensively delaminated and completely separated due to thorough asphalt penetration by various dispersion techniques. To achieve fine dispersion, mechanical forces alone are not sufficient; rather, there should be a thermodynamic driving force to separate the layers into the primary silicate sheets. This thermodynamic driving force is being introduced by inserting a certain coating of surfactants (an agent such as detergent, which reduces surface tension) on each individual layer. These surfactant molecules increase the layer distance.they, moreover, improve the compatibility with the asphalt and can enhance the bonding of because they can be mixed together with the asphalt [3, 9]. Literature review has shown limited studies investigating the rheological and aging effects of modified with local asphalt production. The main objective of this study was to evaluate the rheological properties and aging effect of base asphalt modified with diffrent percentages of through Superpave asphalt binder tests. The control and modified asphalt binders were then artificially aged using rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. The viscosity properties for the binders in the original state, the rutting properties in the original state and after RTFO aging and the fatigue cracking properties at intermediate temperature after RTFO + PAV aging methods were evaluated. Material and Methods Sample modification In this study, base asphalt binder used was PG 64 from Kemaman Bitumen Company, one of major sources in Malaysian mixing plant operations. During sample modification stage, 400 g of asphalt binder was heated to become a fluid in an iron container, and then upon reaching C, was added at 3, 4 and 5 percent by weight of base asphalt binder. All modified asphalt binders were prepared using a Silverson-L4RT high shear mixer at speed of 6000 rpm for 25 minutes at 160 ± 5 0 C. The base and modified asphalt binders were then artificially short-term and then long-term aged through RTFOT [11] and then PAV [12]. Rotational viscosity test [13] This method is used to determine the viscosity of asphalt at application temperatures. The measured viscosity at elevated temperatures can be used to determine whether the binder can be handled and pumped at the refinery, terminal, or hot mix asphalt plant facility. The rotational viscometer (RV) test was used to evaluate the difference in viscous behavior between the control and modified asphalt binder. The temperatures over which the RV test was conducted were 120, 135, 150, and 165 and C using a Brookfield viscometer (Model DV-II+). When the temperature was set at desired temperature, the no.27 spindle was inserted into the sample chamber which containing 10.5 g of asphalt binder. Normally, the selected temperature will equilibrate after min (lab practice showed that the usual equilibrium time is 18 min). At least three readings were subsequently recorded between the 18th and 21st min of the test for each evaluated temperature. The dynamic viscosity at each temperature is the arithmetic mean of these three readings [14-15].

3 998 Advanced Materials Engineering and Technology II Dynamic Shear Rheometer Test [16] A stress-controlled HAAKE dynamic shear rheometer (DSR) was used with 25 mm parallel plates to characterize the mechanical properties of the control and modified asphalt binders prepared under temperatures ranging from 46 to 70 0 C and loading frequency at 10 rad/s (1.59 Hz) [16]. During testing, samples were conducted in a control and homogeny environment. The Superpave performance grading (PG) testing protocol [17] was used to evaluate the control and modified asphalt binder samples. High service temperature (HT) for a binder is determined as the temperature at which the G*/Sin is greater than 1 kpa for unaged binder and greater than 2.2 kpa for the RTFO [11]. In addition to the performance requirements at high and low service temperature; there is a limiting maximum stiffness at the intermediate service temperature (IT) to alleviate fatigue cracking, at which the binder s G*Sin after PAV aged binder condition does not exceed 5000 kpa [12, 15, 18-19]. Fourier transform infrared (FTIR) spectroscopy Chemical characterizations of modified binders before and after ageing were performed using FTIR spectroscopy, Infinity 60AR (Mattson, resolution cm -1). The FTIR can detect molecular vibrations that may be in the form of two atoms in a diatomic molecule experiencing a simple coupled motion to each individual atom in a large polyfunctional molecule undergoing motion. It also can detect the variation of the main functional groups in the asphalt based on the infrared spectra corresponding to molecular structures of different molecular group. In this study, five percent by weight solutions of asphalts were prepared in carbon disulfide. Scans were performed using circular sealed cells (ZnSe windows and 1 mm thickness). All spectra were obtained by 32 scans with iris and 4 cm -1 resolution in wave numbers ranging from 1900 to 500 cm -1 [20-24]. In this study, sulfoxide band and carbonyl band in the infrared spectra related were investigated to determine aging effect of modified asphalt binders. Results and Discussion Viscosity Properties The RV test was used to evaluate the difference in viscous behavior which is considered to be one of important properties since it represents the ability of the binder s to be pumped through an asphalt plant, thoroughly coat the aggregate in asphalt concrete mixture, and be placed and compacted to form a new pavement surface [19, 25]. Fig. 1 shows the viscosities values of asphalt binder containing different percentages of at different setting temperatures. The results clearly showed that the addition of 3-5 % into base binder ( ) increased the binder s viscosity. The results clearly showed that the addition of 3-5 % into base binder ( ) increased the binder s viscosity. It also indicates an improvement when the perecentage of asphalt binder modified with increased. Based on viscosity data, all modified asphalt binders are lower than 3 Pa.s when tested at C hence meet the standard specification of Superpave. Rutting Resistance The effect of the modified asphalt binder on the rutting resistane (G*/ sin δ) was evaluated using DSR. In Superpave specifications, G*/sin from the DSR test is used as a key factor to define the rutting resistance of an asphalt binder at a high-performance temperature [19, 26-27]. In Fig. 2 and Fig.3, all G*/sin values are higher than 1.0 kpa (unaged condition) and 2.2 kpa (RTFO aging condition) at 64 0 C. The G*/sin for unaged and RTFO aging value increases as the percentage of increases. The results suggest that the addition of could increase the rutting resistance of asphalt binder.

4 Key Engineering Materials Vols Fig. 1 Rotational viscosity plots for asphalt binder containing different percentage of Fig. 2 G*/sin δ (kpa) of unaged asphalt binder containing at 64ºC Fig. 3 G*/sin δ (kpa) of RTFOT asphalt binder containing at 64ºC Fatigue Resistance Fatigue resistance (G*.sin δ) of modified asphalt binder after conditioned (RTFO + PAV residual) were determined using the DSR at 25 0 C and the results are shown in Fig. 4. The G*.sin values meet the standard specification of Superpave requirements (maximum 5000 kpa) where the results were found to be 2108, 3038, 3156, and 3296 kpa for the control binder ( ),, and respectively. The lower G*.sin values are generally considered to be desirable characteristic from the standpoint of fatigue cracking resistance. From the results, it is predicted that the modified asphalt binder has slightly lower resistance in term of fatigue cracking at intermediate temperature compared to the base binder. Fig. 4 G*.sin of RTFO+PAV aging asphalt binder containing at 25 0 C

5 1000 Advanced Materials Engineering and Technology II Fourier Transform Infrared Spectroscopy (FTIR) Infrared spectroscopy measures the infrared light absorbed by covalent bond in molecules and it can be used as a tool to quantify ageing properties of modified and unmodified asphalts. The modified and unmodified asphalts were tested in FTIR spectrometer, and the peaks of their IR absorbance were measured at wave number 1700 cm - ¹ and 1030 cm - ¹ which represent the amount of sulfoxide and carbonyl bonds in the binders respectively as indication of aging in the binder. Binders were tested in their original condition (unaged binder), RTFOT aged condition and PAV aged condition [21-22]. The absorbance of the binders at 1700 cm - ¹ (carbonyl bonds ) and 1030 cm - ¹ (sulfoxide bonds) are shown in Fig. 5 and Fig. 6. (a) (a) (b) (b) (c) (c) Fig. 5: FTIR absorbance of the binders at 1700 cm - ¹: (a) Unaged binder; (b) RTFOT aged binder; and (c) PAV aged binder. Fig. 6: FTIR absorbance of the binders at 1030 cm - ¹: (a) Unaged binder; (b) RTFOT aged binder; and (c) PAV aged binder.

6 Key Engineering Materials Vols The IR absorbance of carbonyl bonds (Fig. 5) in the modified asphalt binders increases slightly after RTFO and PAV aging process compared with the unmodified asphalt binders. However, IR absorbance of unmodified asphalt binder shown slightly higher compared with modified binders after PAV aging. The result indicate that the addition of into the asphalt binder could improve the aging process because it can delay the oxidation reaction. Meanwhile, the sulfoxide bonds (Fig. 5) in the control and modified asphalt binders after RTFO and PAV aging shows a different trend with the carbonyl index. The results in this study coincide with the previous study and for this reason, the sulfoxide index is not considered as an aging index in the asphalt binder [41,50 52]. Conclusion In this study, a series of Superpave binder tests were carried out using the rotational viscometer, DSR and FTIR to determine effect of modified binders. From these test results, the followings can be drawn: (1) The addition of can effectively increase the viscosity properties and rutting resistance but slightly decreased the fatigue cracking resistance compare to the base asphalt binder. (2) Based on absorbance peaks of carbonyl bonds, the addition of could delay the aging process of asphalt binder. References [1] C. Fang, R. Yu, Y. Li, M. Zhang, J. Hu, and M. Zhang: Preparation and characterization of an asphalt-modifying agent with waste packaging polyethylene and organic montmorillonite. Polymer Testing. Vol. 32(5) (2013), p [2] H. Zhang, J. Yu, and S. Wu: Effect of montmorillonite organic modification on ultraviolet aging properties of SBS modified bitumen. Construction and Building Materials. Vol. 27(1) (2012), p [3] S.G. Jahromi and A. Khodaii: Effects of nanoclay on rheological properties of bitumen binder. Construction and Building Materials. Vol. 23(8) (2009), p [4] N.I.M. Yusoff, M.T. Shaw, and G.D. Airey: Modelling the linear viscoelastic rheological properties of bituminous binders. Construction and Building Materials. Vol. 25(5) (2011), p [5] M.E. Abdullah, K. Ahmad Zamhari, N. Nayan, M. Hermadi, and M.R. Hainin: Physical properties and storage stability of asphalt binder modified with nanoclay and warm asphalt additives. World Journal of Engineering. Vol. 9(2) (2012), p [6] M.K. Idham, M.R. Hainin, H. Yaacob, M.N.M. Warid, and M.E. Abdullah: Effect of Aging on Resilient Modulus of Hot Mix Asphalt Mixtures. Advanced Materials Research. Vol. 723 (2013), p [7] N. Yarahmadi, I. Jakubowicz, and T. Hjertberg: Development of poly(vinyl chloride)/montmorillonite nanocomposites using chelating agents. Polymer Degradation and Stability. Vol. 95(2) (2010), p [8] D. Ghile. Effects of nanoclay modification on rheology of bitumen and on performance of asphalt mixtures (2006). M. Eng. Thesis [9] Z. You, J. Mills-Beale, J.M. Foley, S. Roy, G.M. Odegard, Q. Dai, and S.W. Goh: Nanoclay-modified asphalt materials: Preparation and characterization. Construction and Building Materials. Vol. 25(2) (2011), p [10] B. Zhang, M. Xi, D. Zhang, H. Zhang, and B. Zhang: The effect of styrene-butadiene-rubber/montmorillonite modification on the characteristics and properties of asphalt. Construction and Building Materials. Vol. 23(10) (2009), p [11] American Society for Testing and Materials (1997). Standard test method for effect of heat and air on a moving film of asphalt (rolling thin-film oven test). New York: ASTM D2872.

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