Modular reinforced soil system used to form a gabion-faced MSE wall. The facing section of the unit is formed by connecting a back panel and diaphragms to the main fascia unit, creating the rectangular-shaped box used for stone confinement. The geogrid reinforcement, fascia and lid are all one continuous panel of mesh. Units are supplied in standard lengths, requiring no cuts on site.

Following on-site assembly, the fascia unit is filled with suitable gabion stone fill. Structural backfill is then placed upon the soil reinforcement geogrids and compacted.

Manufacture

All Terramesh® units are fabricated from high-quality Class A heavily galvanised steel wire with an additional PoliMac® polymeric coating.

PoliMac® is a revolutionary coating exclusive to Maccaferri that can withstand the increasingly aggressive environmental conditions brought on by global climate changes and offers significant advantages over traditional PVC coated wires, including:

  • 10x resistance to abrasion

  • 2x resistance to chemical aggression

  • 4x performance in cold weather

  • 4x resistance to UV rays

Units are produced in Maccaferri's factories around the world and the management and production system in many of these is certified in compliance with ISO 9001.

Accreditation

Terramesh® units are produced in compliance with CPR – Construction Product Regulation 305/2011, having EC marking in compliance with ETA-13/0295. The management and production system is certified in compliance with ISO 9001 and ISO 14001 (related to the environmental management system). It is also BBA HAPAS Certified.

Part 1 – Product 

1.1 Description 

Double twisted steel wire mesh soil reinforcement units with vertical stone facing (Terramesh System) shall be manufactured in compliance with BS EN 10223-3, with Zn-Al alloy and a High Abrasion Resistant (Polimac® or equivalent) polymer coated steel wire. Units are manufactured in compliance with The Construction Products (Amendment etc.)(EU Exit) Regulations 2020 on the basis of UKAD 200026-00-0102 “Steel mesh systems for reinforced fill” and UKTA-0836-22/0022. 

[For Republic of Ireland: The units are manufactured in accordance with Construction Product Regulation CPR 305/2011, and have a CE marking in compliance with EAD 200026-00-0102.] 

The management and production system of the supplier shall be certified in compliance with ISO 9001. 

All listed performances must be verifiable on laboratory test reports conducted by independent research institutes, the relevant documentation shall be submitted to the supervisor for the acceptance of the material. 

1.2 Functional characteristics 

The nominal tensile strength of the steel wire mesh shall be 50 kN/m, in accordance with BS EN 10223-3. 

The maximum wire mesh punching resistance of the steel wire mesh shall not be lower than 65 kN, in accordance with UNI 11437 and ISO 17746. 

The 120 years long-term tensile strength (LTDS) for soil pH levels in the range of 3-13 will be different depending on the fill material used as reported in the table below:  

Fill material 

Maximum particle size (mm) 

LTDS [kNm-1] 

Silt and Clay 

<0,06 

45,8 

Sands 

<2 

45,8 

Sandy gravels 

<9,5 

43,6 

Coarse gravels  

<38 

39,8 

Crushed stones  

<200 

37,5 

The values of the reduction coefficients will be provided by the manufacturer but will have to be validated by a third-party accredited certification institution (e.g. BBA, British Board of Agreement or NTPEP): the relevant accreditation shall be submitted to the supervisor for the acceptance of the material. 

Minimum requirements of Stiffness EA and Strain e at yielding at specific soil confinement pressures: 

Embedded mesh tensile test (BS EN 13738 or ASTM D6706) at soil confinement pressures of: 

Stiffness EA at characteristic yielding not smaller than (=): 

Strain e at characteristic yielding not bigger than (=): 

35 kPa 

750 kN/m 

6.2% 

75 kPa 

1100 kN/m 

4.3% 

150 kPa 

1650 kN/m 

3.1% 

 

1.3 Materials 

The double twisted steel wire mesh shall be manufactured with hexagonal 8x10 mesh type (BS EN 10223-3, Table 2), woven with a drawn steel wire core of 2.70 mm in diameter, with a minimum quantity of 245 g/m2 of Zn-Al metallic coated alloy, in accordance with ISO 7989-2 and BS EN 10244-2, Table 2, Class A. 

The double twisted steel wire mesh shall be resistant to outwearing accelerated ageing when subject to test in a Sulphur dioxide environment (ISO 22497): after 28 cycles of discontinuous test, the mesh shall not show more than 5% of DBR (Dark Brown Rust). 

The metallic coated wire core shall be protected with a high abrasion-resistant polymer coating (Polimac® or equivalent) with a nominal thickness of 0.5 mm, resulting in a nominal overall diameter of 3.70 mm.  

1.4 Polymer coating 

The polymer coating shall not contain heavy metals and be resistant to:  

  • Outwearing accelerated ageing in salt spray (ISO 9227): after 15,000 hours of exposure, the mesh shall not show more than 5% of DBR (Dark Brown Rust). 

  • Abrasion test, in accordance with the procedure described in ASTM A975-23: after 400 cycles the polymer coating shall not expose the metal wire.       

  • UV radiation, in accordance with ISO 4892-3, type 1A: after 2,500 hours of exposure to QUV-A the tensile strength and elongation at break of the base compound shall not change more than 25% from the initial test results. The polymer coating shall not release phthalates during the degradation process. 

  • The brittleness temperature shall be lower than -35°, tested in accordance with ASTM D746.  

  • Corrosion spread test, in accordance with the procedure described in ASTM A975-23: the maximum corrosion length measured shall be always less than a mesh repetition on wire samples immersed in an acid solution with an unprotected end for 2500 hours. 

1.5 Lacing 

Stainless steel rings shall be used for fastening operations and shall have the following characteristics: 

  • Diameter: 3mm 

  • Tensile strength > 1,550 MPa 

  • Pull-apart strength > 2.0 kN 

1.6 Environmental and sustainability properties 

1.6.1 Environmental Product Declaration

The soil reinforcement (Terramesh® System) units shall have a Type III Environmental Product Declaration (EPD) registered and certified in accordance with ISO 14025 and BS EN 15804, to evaluate the environmental impact and give the possibility to calculate the Life Cycle Assessment (LCA) of the designed technical solution. 

Such sustainability performances/requirements have to be reported in the Type III EPD certificate; certifications of not authorized bodies or self-certificates issued by the manufacturer, are not allowed. 

The value shall be declared, as per Table 1, in terms of Global Warming Potential (GWP 100 years) and expressed in kg CO2-Equiv./kg. 

Table 1 – Environmental and sustainability properties 

Global Warming Potential (GWP 100 years) 

ISO 14025 

BS EN 15804 

certified numeric value 

[kg CO2-Equiv./kg] 

1.6.2 Environmental harmlessness 

The polymer-coated steel wires shall be tested to ensure their Environmental Harmlessness according to the following procedures: 

  • Synthetic Precipitation Leaching Procedure (SPLP) preparation as per EPA 1312 and Metals in Water by ICPMS (low level) as per EPA 6020B in which the presence or not of 31 different metals shall be analysed using atomic spectroscopy.  

The results shall be in compliance with (a) Water Framework Directive 2000/60/EC; (b) CCME Water Quality Guidelines for the Protection of Aquatic Life, Freshwater; (c) U.S. EPA National Recommended Water Quality Criteria (Aquatic Life, Freshwater), 2006. 

  • PFAS test in water by SPE/LCMS as per EPA 537.1 in which the presence or not of 28 different PFAS shall be analysed, showing that the polymer-coated steel wires are PFAS free. Resulting in a concentration lower than 2 ng/L of PFOS and PFOA and < 4 ng/L for other PFAS. 

  • ELUATE Tests on environmental safeness, conducted as per M GEOK E:2016, shall ensure that the polymer coating is not critical for the environment. 

  • Smoke toxicity tests conducted as per ISO 5659-2 and BS EN 17084 shall ensure a Gases Conventional Index of Toxicity after 8 minutes sampling CITG (8) < 0.10 and a HCl concentration < 36 ppm 

Part 2 – Execution 

The product’s conformity shall be certified by a third-party Notified Body, according to the The Construction Products (Amendment etc.)(EU Exit) Regulations 2020, which shall assess the quality control process at the supplier’s production facility.? 

[For Republic of Ireland: The product’s conformity shall be certified by a third-party notified Body, according to CPR 305/2011, which shall assess the quality control process at the supplier’s production facility. Prior to the installation, and on each consignment of gabion units to the job site, the contractor shall provide the Supervisory Body with the relevant documentation (Declaration of Performance, D.o.P.) in original form, where product and supplier names, quantities and destination are specified.] 

Soil reinforcement units shall be opened, unfolded and pressed out to their original shape. Front, back, and end panels shall be lifted to a vertical position. Once units are assembled and the foundation has been prepared, levelled and graded, pre-assembled units shall be placed in position empty and fastened to adjacent units to form a continuously connected, monolithic structural unit. All connections shall be in accordance with BS EN 10223-3.  

The stone fill material used to fill the front section of the soil reinforcement unit shall be provided in the proper sizes and quality. Rocks shall be hard, angular to round, durable and of such quality that they shall not disintegrate on exposure to water or weathering during the life of the structure. Care shall be taken to ensure that the polymer coating is not damaged. After each 300 mm layer of rock is placed into the cell, sufficient hand manipulation of rock shall be performed to minimize voids and achieve a maximum density of rock in the gabion. Rocks in exposed vertical faces shall be hand-placed to reduce voids on the outer face. Rock shall be overfilled to approximately 25-40 mm to allow for natural settlement. 

Once the rock-filled section is complete, a geotextile filter shall be placed behind the facing section and the soil backfilling operations may start. Compaction within 1.5 m from the face shall be performed with a light compactor, to prevent excessive vibration into the rock-filled section. Soil shall be placed in 300 mm layers and be compacted to the required level. The soil material shall be of good quality, free draining, granular or selected. The recommended soil gradation is between 0.02- and 6-mm. Compaction shall be performed to 95% of standard Proctor, by using conventional compaction equipment.