• Document: The Use of Polymer Modification of Bitumen for Durant Hot Asphalt Mixtures
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Journal of Applied Sciences Research, 4(1): 96-102, 2008 © 2008, INSInet Publication The Use of Polymer Modification of Bitumen for Durant Hot Asphalt Mixtures 1 Behbahani Hamid, 2Ziari Hassan, 3Noubakhat Shams 1 Full Professor, Department of Civil Engineering, Iran Science and Technology, Tehran, Iran. 2 Assistant Professor, Department of Civil Engineering, Iran Science and Technology, Tehran, Iran. 3 Ph.D. Student, Department of Civil Engineering, Iran Science and Technology, Tehran, Iran. Abstract: The add to in road traffic during the last two decades in mixture with an inadequate degree of protection due to shortage in funds has caused an accelerated and continuous deterioration of the road network in Iran. To alleviate this process, several types of procedures may be efficient, e.g., securing funds for preservation, improved roadway design, use of better quality of materials and the use of more effective construction methods. The use of polymer in asphalt combination as a modifier started in the 80s of the last century and has been tested in a number of countries around the W orld. In this research, SBS as one sort of polymers is used to investigate the impending prospects to enhance asphalt mixture properties. Two types of polyethylene were extra to coat the aggregate SBS and EVA. The polymers were introduced to the mixture in two states (Grinded and not Grinded). Marshall Mix design was used, first to verify the best bitumen binder content and then further to test the modified mixture properties. The optimum asphalt substance was 5.4%. Marshall Mix design requires the purpose of the percentages of air voids and air voids of mineral aggregate. The research involves selected laboratory performance tests, which were conducted on modified asphalt mixtures. The results indicated that grinded SBS polymer modifier provides better production properties. T he recommended proportion of the modifier is 3% by the mass of bitumen content. It is found to raise the strength, reduce the density and slightly increase the air voids and the voids of stone aggregate. Key words: Hot asphalt mixtures, SBS, EVA, Best binder content, Fatigue achieve, Marshal Test, Durant INTRODUCTION cracking. Pavement asphalt mixtures are sensitive to degradation agents such as heat, oxygen, ozone, The increase in road traffic during the last two chemicals, etc. to which they are exposed during their decades in combination with an insufficient degree of preparation, storage and service. maintenance due to shortage in funds has caused an Considerable research in recent years has focused accelerated and continuous decline of the road network on improving the functional properties of the AC. in Iran. To alleviate this process, several types of The use of synthetic polymers as additives, via measures may be effective, e.g., securing funds for chemical or physical blending, has been shown to maintenance, improved roadway design, use of better greatly improve the performance of conventional quality of materials and the use of more effective asphalts. The thermoplastic nature of these binders has construction methods. The road network in Iran has a displayed the ability to combine properties of elasticity, primarily flexible pavement design [2 ]. Several factors strength and adhesion to increase road life [1 0 ]. influence the performance of flexible courses, e.g., the Improved properties also include greater resistance properties of the components (binder, aggregate and to aging and stability at high temperatures. additive) and the proportion of these components in the Thermoplastic copolymers such as styrene-butadiene- mix. Bitumen can also be modified by adding different styrene (SBS) have exhibited the greatest potential for Petroleum asphalted cement (AC) composed of bitumen modification. The SBS structure consists of a aromatic hydrocarbons, paraffin and resins has been triblock chain having twophase morphology of used for a variety of purposes, but most importantly for styre nic bloc k domains within a matrix of road surfacing. polybutadiene. The polystyrene end-blocks confer Certain AC binder properties are required in this strength on the polymer, while the rubbery application to prevent the occurrence of three major polybutadiene gives elasticity. W hen SBS is blended pavement stresses, i.e., rutting, fatigue and thermal with AC, it is believed the electrometric phase of SBS Corresponding Author: Behbahani Hamid, Full Professor, Department of Civil Engineering,

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