The subject-matter of the invention is geocell manufactured from double-side textured multilayer , strips from modified polyester and secured during the technological process with an additional protective layer manufactured from PVC.

Geocells are manufactured in assemblies - also called sections - that usually consist of several tens of strips connected in a series of ultrasonic welded seams, aligned perpendicular to the longitudinal axis of the strips. A section prepared for transport and storage consists of an assembly of collapsed adjoining strips. When expanded the section forms walls of a flexible, 3 -dimensional cellular confinement system.

Strength and mechanical properties of the geocells and all other geosynfhetics designed for reinforcement depend on to the base material used for the manufacture thereof and the method of manufacture.

Due to the decrease of the tensile strength of the reinforcement, resulting from the properties of the plastic material, the long-term strength (Fd) usually ranges from 10 to 40% of ultimate (short-term) tensile strength.

For the known geocells manufactured from various types of polyethylene or polypropylene or modifications thereof - in case of difficult applications where the predictable service lifetime spans from 60 to 120 years - certain restrictions arising from the creep factor of the material can affect the lowering of the rate of reinforcement load i.e. lowering of the performance of the reinforcement material.

For that reason designers of geosynthetic reinforcements limit the application of the polyolefm geocells to: the reinforcement of weak subsoils under the pavements of temporary roads, forestry roads and other road structures designed for short use as well as for the erosion protection of earth slopes, outflow sewers, ditches and reconstruction of flood banks. A trial manufacturing of geocells with higher stiffness and creep resistance is also known to have been made through ultrasonic pressure-less welding of a plurality of polymer strips comprising multiphase polymeric material (Application PCT7US2007/063082). In this case the multiphase material comprises a rigid continuous phase and an elastic phase dispersed in the rigid continuous phase. The rigid phase comprises an engineering thermoplastic resin selected from the group consisting of polyesters, polyamides and polyurefhanes in the amount of 70% of the weight of the rigid phase and a polymer selected from the group consisting of high density polyethylene (HDPE), medium density polyethylene (MDPE) and combinations thereof. The elastic phase comprises polymeric material selected from the group consisting of linear low density polyethylene (LLDPE); ethylene-alpha olefin elastomer or plastomer; ethylene-propylene elastomer; ethylene-propylene diene elastomer; ethylene-acrylate ester or mefhacrylate ester copolymers and terpolymers; butyl rubber; nitrile rubber; silicone elastomer; polyurethane elastomer; styrene block copolymers; and combinations thereof. The multiphase polymer material may comprise popularly known fillers, UV stabilizers, pigments and dyes.

A trial manufacturing of geocells comprising a plurality of strips is also known to have been made (application US 2008/0210688 Al) showing more resistance against UV light, humidity or heat than virgin high density polyethylene, and wherein the at least one outer layer comprises a UV absorber (HALS type absorber or inorganic barrier particles).

In this type of geocell at least one polymeric layer of each polymeric strip comprises a polymer selected from the group consisting of high density polyethylene (HDPE), medium density polyethylene (MDPE), ethylene-acrylic acid ester copolymers and terpolymers, ethylene-methacrylic acid ester copolymers and terpolymers, acrylic acid ester copolymers and terpolymers, aliphatic polyesters, aliphatic polyamides, aliphatic polyurethanes, mixtures thereof: and mixtures thereof with at least one polyolefin. Each polymeric strip may further comprise additives selected from the group consisting of antioxidants, pigments, dyes, carbon black, and barrier particles. In case of building constructions such as earth retention structures, bridge abutments, road and rail embankments with base reinforcement where long-term use had been foreseen require geocells of high long-term strength values. The geocell material for such applications must show high creep resistance and the value of the material coefficient - where the decrease in strength due to creep factor (Al) throughout the service lifetime of the construction is assumed - shall be lower than 2.5.

Geocell with reduced creep and high microbiological and hydrolysis resistance in acid and alkaline environments wherein a plurality of strips is connected in a series of ultrasonic welded seams, according to the invention shows that each strip comprises at least one outer polymeric layer with high hydrolysis and weather resistance and at least one inner polymeric layer with reduced creep.

At least one outer polymeric layer is formed from unmodified PVC or from soft PVC or from a blend of PVC with chlorinated polyethylene or from a blend of PVC with E/VA copolymers or/and from E/VA copolymers grafted with vinyl chloride or from vinyl chloride and vinyl acetate copolymers or from vinyl chloride and vinylidene chloride copolymers or from vinyl chloride and acrylic ester copolymers or from vinyl chloride and olefin copolymers or from chlorinated polyvinyl chloride.

At least one inner polymeric layer of the strip is formed from Poly(ethylene terephthalate) PET or from Poly(ethylene terephthalate) PET modified with PBT or/and PCT additive or from Poly(ethylene terephthalate) modified with the additive of segmented copolyetherester, grafted polyolefin and/or grafted polybutadiene.

In at least one inner polymeric layer of the strip there is PET and/or modified PET in a form of film, band, textile, impregnated textile, fabric or impregnated fabric.

In at least one outer polymeric layer of the strip there are glass fibres in a form of rowing, mat or veil.

At least one polymeric layer of each strip contains from 75 weight percent to 100 weight percent PET, from 0 weight percent to 25 weight percent impact strength modifiers, from 0 weight percent to 15 weight percent additives selected from the group consisting of pigments, dyes, carbon black, fillers and additives lowering thermal expansion (CLTE). Additives lowering thermal expansion take the form of fabric or powder of an average size of particles of less than 40 microns.

At least one inner polymeric layer of the strip is formed from Poly(ethylene terephthalate) modified with additives selected from the group consisting of SEBS-g- MA, SEBS-g-GMA, HDPE-g-MA, HDPE-g-GMA, LDPE-g-MA, LDPE-g-GMA, LLDPE-g-MA, LLDPE-g-GMA, POE-g-MA, GMA, EGMA, EMA, EBA, EBAGMA, EEAGMA, PTMO, LDPE grafted with derivatives of 2-oxazoline and combinations thereof.

At least one inner polymeric layer of the strip is formed from Poly(ethylene terephthalate) and contains fillers and additives lowering CLTE selected from the group consisting of whiskers, aramid fibres, cut glass fibres, glass beads, metal oxides, calcium carbonate; calcium sulfate, silica, kaolin, carbon fibres, carbon nanotubes, talc, bentonite, montmorillonite, wollastonite, carbon black, mica, carbon - aramid hybrid fibres, glass - aramid fibres, carbon - aramid fibres and combinations thereof.

This disclosure according to this invention is presented in the examples hereinunder.

Example 1 :

Geocell with reduced creep and high microbiological and hydrolysis resistance manufactured from multi-layer strips according to the invention comprises two outer layers formed from polyvinyl chloride and one inner layer formed from Poly(ethylene terephthalate) containing 15 weight percent impact strength modifier and 5. weight percent talc.

Example 2:

Geocell with reduced creep and high microbiological and hydrolysis resistance manufactured from multi-layer strips according to the invention comprises two outer layers formed from polyvinyl chloride and one inner layer formed from Poly(ethylene terephthalate) containing 10 weight percent impact strength modifier and 12 weight percent woUastonite.

Example 3 :

Geocell with reduced creep and high microbiological and hydrolysis resistance manufactured from multi-layer strips according to the invention comprises two outer layers formed from polyvinyl chloride and two inner layers: one inner layer formed from Poly (ethylene terephthalate) containing 5 weight percent impact strength modifier and second inner layer formed from Poly(ethylene terephthalate) containing 10 weight percent glass fibres and 10 weight percent impact strength modifier.