According to foreign institutions, global geotextile 88% (output value) is polypropylene, and polyester only accounts for 4%. According to the NGS (Nordic regional geommaterial certification body) 102 geosynthetics, 87 of them are polypropylene PP Geotextile, 10 are polyester, and 5 are polyethylene products. The nonwoven geotextiles are all polypropylene.
Obviously, this is quite different from the proportion of polypropylene geotextiles used in our country. Most of the nonwoven geotextiles in China are polyester, so why do most foreign geotechnical works use polypropylene geotextiles? Through research, the use of polypropylene geotextiles in geotechnical engineering abroad is mainly based on considerations of performance, economy, durability and safety.
Polypropylene (PP) has a specific gravity of 0.91g/cm3, which is the lightest of the common polymers. The proportion of polyester is 1.38g/cm3, which is 1.5 times that of polypropylene. The fabric with the same weight, the polymer in the unit area of the PP Geotextile, is that the fiber has more actual body volume, better physical properties, and better function of reinforcement, protection and filtration.
Especially, polypropylene filament needling geotextile, under the same weight condition, its tear strength is 2.5-2.6 times of polyester short fiber geotextile and 1.5-1.7 times of polyester filament geotextile; top breaking strength is higher than polyester short fiber needled geotextile 80-90%, and higher 20-30% than polyester filament needle geotextile.
The international standard and engineering design are all used in strong specifications, while the geotextile weight is the norm in China. But this situation is changing. The standard of the GB/T 17639 filament needling geotextiles revised in 2008 and the new revised GB/T 17638 short fiber needling geotextile standard in 2008 are unified with the naming method of the tensile strength as the specification model of the geotextile.
In this case, the economics of polypropylene geotextiles can be seen. For example, 400g/ geotextiles commonly used in water conservancy projects can choose two kinds of geotextiles:
Among them, 20 represents tensile strength, 6 represents width, 400 and 300 represent geotechnical Burke weight respectively. In this way, a ton of polyester geotextiles has 2500m2, while PP Geotextile have 3333 m2, 833 more than polyester (covering 33.3% of the area).