Polypropylene has a high abrasion resistance , similar to polyester fibres, and has extremely good resistance to repeated bending making it advantageous for the rough handling on a construction site. (42)
polypropylene fibres have excellent strength , which is dependent on the degree of polymerization. (38)
6- Low extension under load
7- Resistance to micro – organisms and insects
Polypropylene fibres are very resistant to attack by bacteria , mildew, and insects (44)
Besides all this polypropylene has two major economic advantages , it has a short simple route and is easily obtainable from oil or natural gas. Also it has a relatively low melting point (260 0 F), this means that energy costs and capital costs are lower than other polymers. (42)
In road paving application, polypropylenes are often the fibre of choice due to their excellent physical properties , hydrophobicity , resistance to acids, mildew resistance , low density and low cost. (45)
Because of the excellent physical and chemical properties of these two fibres ( polyester and polypropylene ) , they were used with confidence and were considered the material of choice in this research.