The nonwoven geotextile Drefon® S is a permeable separation layer with variable thicknesses, according to the individual unit weight, between 2 and 15 mm. The product can be used:

• to solve problems of mixing between fine soil particles and fill aggregates
• as a filter in all cases in which it is necessary to retain soil particles subject to erosion due to a hydraulic forces
• with a protective function for surfaces exposed to mechanical damage
• as a draining element of fluids.

Drefon® S is different from other nonwoven geotextiles, offering in particular:

• Higher resistance to mechanical damage with a considerably inferior unit weight, thanks to a high level of deformation energy which the material can absorb, giving substantial economic saving
• Higher short and long term protection efficiency, that is greater safety in protection of waterproofing systems, thanks to the use of virgin high tenacity polypropylene fibres, mechanically bonded in order to obtain a high thickness product with excellent puncture resistance
• U.V. radiation resistance, thanks to the use of fibres which are U.V. stabilised, with the advantage of not needing to cover the geo-textile immediately after installation, thus avoiding fragmentation of work processes
• Even fibre distribution within the geotextile, thanks to the carding process before the needle-punching of the fibres, which results in uniformity of mechanical and hydraulic characteristics without "weak points" within the fabric
• Higher hydraulic permeability and higher drainage capacity, being all heating treatment excluded from manufacturing processes, which means safety of use in the presence of water
• Roll size customized according to job site needs, up to the width of 6.60 m, with saving of time and money
• High chemical and biological resistance and high durability, thanks to the use of high quality virgin polypropylene fibres, that means initial product characteristics are conserved at length even in aggressive environments

In the road pavements construction or rehabilitation, in the construction of granular subbases and road and railways embankments the geotextile Drefon® S keeps the fill material separate from the fine subgrade soil.

Thanks to the in-plane drainage capability of Drefon® S, the porewater can be removed from the works.

The integrity of Drefon® S can be guaranteed even in cases of particularly severe installation stresses (use on soft soils, with coarse, sharp edged gravel compacted in thin layers with heavy machinery) thanks to the high level of energy absorption which it can endure, adapting to all irregularities in the subgrade.

 

In coastal and river bank erosion control structures Drefon® S is placed below the covering layer (concrete blocks, rock riprap, gabions) thus preventing the erosion of soil particles caused by the current or by the wave action. The characteristics of resistance and deformability of Drefon® S guarantee prevention of damage during installation even with low unit weight materials; so the use of heavier nonwovens, which are more subject to pore clogging by fine particles, can be avoided.

 

In the construction of waterproofing systems Drefon® S ensures an efficacious mechanical protection of the geomembranes which come in contact with rough and irregular surfaces, such as in tunnels, dams, reservoirs, canals, and other concrete works, or which are subject to the puncturing action caused by draining gravel in landfills.

The nature of the fibres gives Defon® S chemical inertia which makes it suitable for use in contact with fresh concrete or substances normally present in landfill leachate.
 

Resistance to installation damage is one of the most important factors in geotextile design, especially when coarse grained, sharp edged fill material is used. A standard test method trying to simulate these dynamic stresses is the Cone Drop Test acc. EN 918, in which Defon® S geotextiles yields excellent technical values when compared to other products on the market (see data sheets).
As such a test can only be done in a laboratory and not on-site, we have developped a simple test demonstrating the different performance of the various geotextile types clearly and closely to practice: the "Hammer Test". This test shows significant differences between the extremely robust Drefon® S geotextiles and other products, even continuous filament nonwovens!
 

As it is difficult to exactly reproduce simple beats with a hammer, we have developped this test further to a modified drop test with pyramid piston. A geotextile sample is fixed in a ring clamp, and a pyramid piston with varying falling weight is dropped onto the sample from a certain height. As underlying medium, we use plastilline (to simulate weak subgrade), but if necessary, the test can also be carried out with the actual on-site subgrade material.This simple practical test again proves the superiour performance of Drefon® S geotextiles: Drefon® S withstands all these dynamic stresses without any harm, whereas even continuous filament nonwovens are perforated easily, which makes their suitability as separation and filtration elements questionable - especially when sharp edged crushed fill material is used, or in hydraulic construction!