Scientific Research and Essays Vol. 6(11), pp. 2234-2241, 4 June, 2011 Available online at http://www.academicjournals.org/SRE DOI: 10.5897/SRE10.960 ISSN 1992-2248 ©2011 Academic Journals Review An overview on the use of geosynthetics in pavement structures Sina Mirzapour Mounes 1 , Mohamed Rehan Karim 1 *, Abdelaziz Mahrez 1 and Ali Khodaii 2 1 Center for Transportation Research, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia. 2 Department of Civil Engineering, Amirkabir University of Technology, Tehran, Iran. Accepted 6 May, 2011 Pavement structures commonly fall into two main categories, namely, flexible and rigid pavements. Such structures just as other structures are susceptible to different types of distresses. In order to minimize the deterioration of pavements, geosynthetic reinforcement is one of the techniques adopted to improve their performance. As a result, employment of different geosynthetics to pavement structures is reported by various researchers. This paper aims to present and discuss the findings from some of the studies on utilizing geosynthetics in flexible pavements. Furthermore, three most common usages of geosynthetics, so called, fluid barrier, strain absorbing, and reinforcement agent in pavement structures are investigated in this paper. Key words: Pavement deterioration, geosynthetics, pavement reinforcement, cracks, rutting, durability. INTRODUCTION Constant increases in traffic frequency and axle loads place great demands on the existing road network. The horizontal stresses induced between layers soon result in crack formation, and any local differential settlements also lead to cracking of the asphalt layer. These stresses result in crack formation caused by horizontal forces and by local differential settlements. Reinforcement of asphalt mixes is one approach taken to improve pavement performance. Reinforcement generally consists of incur- porating certain materials with some desired properties within other material which lack those properties (Mahrez et al., 2003). The principal functions of reinforcement in asphalt concrete is to provide additional tensile strength in the resulting composite, by increasing the amount of strain energy that can be absorbed during the fatigue and fracture process of the mix (Mahrez et al., 2005). Asphalt reinforcement using geosynthetic has received considerable attention by road authorities as viable solutions to enhance flexible pavement performance. Geosynthetic reinforcement is simply embedding oriented geosynthetic materials in the pavement structure (Abtahi et al., 2009). The introduction of this technology to the *Corresponding author. E-mail: rehan@um.edu.my. Fax: +603- 79552182. Tel: +603-79675339. transportation industry was mainly prompted by the unsatisfactory performance of traditional road materials exposed to dramatic increases and changes in traffic patterns, a need that still exists. Paving synthetics in asphalt and concrete overlays were first tested in the 1960’s with Geotextile (paving fabric). Regular testing and usage of paving fabric began in the mid 1970’s. The test reports and numerous test sections conclusively proved its value. Since then usage has increased to over 100 million square yards annually in the United States and maybe double that worldwide according to the Industrial Fabrics Association (Barazone, 2010). Paving grids and composites were first used in Europe in the early 1980's and in the late 1980's in North America with the addition of a grid composite, grid and fabric. Grid usage is slowly growing and is now in the millions of square yards. Testing began on paving grids and composites in the early 1990’s and the results are just becoming available (Barazone, 2010). TYPES AND CLASSIFICATION OF GEOSYNTHETICS Geosynthetic is a planar product manufactured from a variety of synthetic polymer materials that are specifically fabricated to be used in geotechnical, geoenvironmental,