This paper describes polymer modification of bitumen with gamma-irradiated recycled (γ- ) low-density polyethylene. The recycled low-density polyethylene ( ) was obtained from greenhouse films exposed to sunlight at least one year. The surface of the was treated by gamma beam irradiation that provided formation of free radicals and some functional groups that may contribute to the creation of strong chemical bonds between polymer modifier and bitumen. Five different samples of bitumen/γ- compositions with the modifier content, wt. %: 1, 3, 5, 7 and 9, were prepared. The effects of the γ- on original and aged bitumen were investigated by means of morphological, chemical, and physical testing program, including FTIR spectroscopy, conventional tests, rotational viscosity (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR) tests. Superior performing asphalt pavements (Superpave) specifications were used to analyze mechanical test results as well as to determine the performance grades (PG) of the binders. Optimum usage of the γ- as modifier in bitumen were suggested after testing program. The results reveal the stiffening effect of the γ- on bitumen that provide enhanced temperature susceptibility and also promise better performance grades (PG) with γ- polymer modification. 1. Introduction The modification of bitumen by means of polymers is the most widespread method in flexible pavement applications. The polymers such as Styrene Butadiene Styrene (SBS), Ethylene vinyl acetate (EVA) are satisfactorily used to enhance temperature susceptibility by increasing stiffness at high temperature and decreasing stiffness at low temperature [1–4]. In addition to SBS, various polymers are utilized in bituminous materials. Polyolefins such as low-density polyethylene (LDPE), high density polyethylene (HDPE), and polypropylene (PP) have been used as modifier, for generally to enhance mechanical properties of bitumen [5–8]. On the other hand, using recycled polymers contributes to reducing amount of waste materials; it has many benefits, such as environmental protection, lower energy consumption, and their affordable cost. Therefore, it is fundamental to find an application area for recycled polymers, in order to increase their commercial use [9–11]. The aim of this work is to study the effect of recycled LDPE (LDPER) as modifier on bitumen by means of morphologic, chemical, and mechanical test methods. However, there is no chemical reaction between LDPER and bitumen which results in a two-phase mixture after the preparation of modified bitumen. In order
References
[1]
D. R. Gershkoff, J. Carswell, and J. C. Nicholls, Rheological Properties of Polymer-Modified Binders for Use in Rolled Asphalt Wearing Course, Transport Research Laboratory, Crowthorne, UK, 1997.
[2]
U. Isacsson, “Laboratory investigation of polymer modified bitumens,” Journal of the Association of Asphalt Paving Technology, vol. 68, pp. 35–63, 1999.
[3]
G. D. Airey, “Rheological evaluation of ethylene vinyl acetate polymer modified bitumens,” Construction and Building Materials, vol. 16, no. 8, pp. 473–487, 2002.
[4]
A. Pérez-Lepe, F. J. Martínez-Boza, C. Gallegos, O. González, M. E. Mu？oz, and A. Santamaría, “Influence of the processing conditions on the rheological behaviour of polymer-modified bitumen,” Fuel, vol. 82, no. 11, pp. 1339–1348, 2003.
[5]
M. García-Morales, P. Partal, F. J. Navarro, F. Martínez-Boza, M. R. Mackley, and C. Gallegos, “The rheology of recycled EVA/LDPE modified bitumen,” Rheologica Acta, vol. 43, no. 5, pp. 482–490, 2004.
[6]
G. Polacco, S. Berlincioni, D. Biondi, J. Stastna, and L. Zanzotto, “Asphalt modification with different polyethylene-based polymers,” European Polymer Journal, vol. 41, no. 12, pp. 2831–2844, 2005.
[7]
N. Z. Habib, I. Kamaruddin, M. Napiah, and I. M. Tan, “Rheological properties of polyethylene and polypropylene modified bitumen,” International Journal Civil and Environmental Engineering, vol. 3, pp. 96–100, 2011.
[8]
C. F. Ouyang, Q. Gao, Y. T. Shi, and X. Q. Shan, “Compatibilizer in waste tire powder and low-density polyethylene blends and the blends modified asphalt,” Journal of Applied Polymer Science, vol. 123, no. 1, pp. 485–492, 2012.
[9]
M. García-Morales, P. Partal, F. J. Navarro, and C. Gallegos, “Effect of waste polymer addition on the rheology of modified bitumen,” Fuel, vol. 85, no. 7-8, pp. 936–943, 2006.
[10]
Z. Z. Ismail and E. A. AL-Hashmi, “Use of waste plastic in concrete mixture as aggregate replacement,” Waste Management, vol. 28, no. 11, pp. 2041–2047, 2008.
[11]
F. J. Navarro, P. Partal, M. García-Morales et al., “Bitumen modification with reactive and non-reactive (virgin and recycled) polymers: a comparative analysis,” Journal of Industrial and Engineering Chemistry, vol. 15, no. 4, pp. 458–464, 2009.
[12]
Y. H. Gad, M. M. Magida, and H. H. El-Nahas, “Effect of ionizing irradiation on the thermal blend of waste low density polyethylene/ethylene vinyl acetate/bitumen for some industrial applications,” Journal of Industrial and Engineering Chemistry, vol. 16, no. 6, pp. 1019–1024, 2010.
[13]
V. Wegan, Sampling for Microscopy-Test Procedure, Danish Road Institute, 1996.
[14]
J. Read and D. Whiteoak, The Shell Bitumen Handbook, Shell Bitumen, Thomas Telford, London, UK, 5th edition, 2003.
[15]
H. U. Bahia and D. A. Anderson, “Strategic highway research program binder rheological parameters: background and comparison with conventional properties,” Transportation Research Record, no. 1488, pp. 32–39, 1995.
[16]
J. P. Zaniewski and M. E. Pumphrey, Evaluation of Performance Graded Asphalt Binder Equipment and Testing Protocol, West Virginia University, 2004.
[17]
G. D. Airey, “Rheological properties of styrene butadiene styrene polymer modified road bitumens,” Fuel, vol. 82, no. 14, pp. 1709–1719, 2003.
[18]
S. Liu, W. Cao, J. Fang, and S. Shang, “Variance analysis and performance evaluation of different crumb rubber modified (CRM) asphalt,” Construction and Building Materials, vol. 23, no. 7, pp. 2701–2708, 2009.
[19]
H. I. A. Wahhab, I. A. Al-Dubabe, I. M. Asi, and M. F. Ali, “Performance-based characterization of Arab asphalt,” Building and Environment, vol. 33, no. 6, pp. 375–383, 1998.
