From more than two decades , textile materials constructed of synthetic polymer fibres, which provide a biologically and chemically inert fabric structure, have been utilized in the construction of roads , drainage systems, and other civil engineering projects ,(29) as these fibre materials can guarantee long-term durability between 20 and 100 years.
Internationally dominant in this sector are the polymers polyester and polypropylene, which together account for about 85% of all geotextiles production.(31)Polyethylene, polyamide (nylon) , glass fibres and other synthetics are also used but to a lesser extent. (12) High – performance fibres such as aramid, carbon and high tenacity vinyl fibres are gradually increasing their market share and have taken the place of conventional and nontextile materials. (32)
Natural fibres are used to a much lesser extent , particularly where soil surface need to be stabilized and protected from erosion , but their potential in such applications is promising because of their lower price, environment- friendly character and technical properties . These fibres include jute , kenaf, coir, cotton, sisal and ramie. Other natural materials such as palm leaf, wood and split bamboo also have their geotechnical applications .(33)
As polyester and polypropylene fibres are the two main fibres used in this research, because they are the most suitable fibres for road paving application ,so this part of the chapter is going to provide detailed information on the properties of these two fibres.