Terrafix erosion control blocks ®

Terrafix is an interlocking environmentally acceptable element made of high strength concrete. It was specifically designed to provide a flexible lining where cost-effective protection against wind and water erosion is required. Terrafix blocks are available in three different thicknesses and can be laid in a variety of configurations to suit most site conditions.

 Examples  |  Specsheet  
Terrafix erosion control retaining blockThe elements are made out of durable concrete and can therefore safely be used in most saline or polluted conditions. Units interlock laterally and offer a secure yet flexible lining.

They are highly permeable, but can be made impermeable by either placing an impervious membrane underneath the blocks or by grouting the structure with concrete or mastic.

This makes it the ideal product to help combat the rapid degradation of our rivers and streams, caused by unbridled urbanisation and poor farming practices all over South Africa and the world.

Terrafix can help prevent our soil being eroded away, while still being permeable enough to help preserve our precious ground water reserves and biodiversity.

Terrafix units are available in three thicknesses – namely 100, 120 and 150 mm. They can be laid in different configurations ranging from four blocks to ten blocks per square metre. In this way over-design and overspending can be avoided.
Block: Terrafix 100 
Blocks/m² (measured on the face) 4-10
Block mass/kg 13
Block infill volume/m³ 0.004
Ave. constructed mass kg per m² of area 190
Block wall thickness 40
Block: Terrafix 120
Blocks/m²(measured on the face) 4-10
Block mass/kg 16
Block infill volume/m³ 0.005
Ave. constructed mass kg per m² of area 235
Block wall thickness 40
Block: Terrafix 150
Blocks/m²(measured on the face) 4-10
Block mass/kg 21
Block infill volume/m³ 0.006
Ave. constructed mass kg per m² of area 300
Block wall thickness 40
Terrafix patterns that are possible Terrafix patterns for erosion control
Variations of patterns possible with the Terrafix block


1. Embankments and slope stabilisation:

Road and railway bridge abutments can be protected against wind and water erosion with good effect, and erosion problems or aesthetic considerations of embankments and cuttings can be effectively countered with the TERRAFIX system. Protection is offered to a varying degree by allowing the choice of appropriate laying patterns and thicknesses.

2. Riverbank and shoreline protection:

Sites subject to wave erosion may be protected with TERRAFIX. The lining can be strengthened with ground anchors or made impervious by employing partial or total concrete or mastic grouting. Hydrostatic pressure relief openings must be provided where necesarry.

Terrafix concrete block applications Terrafix concrete block applications
Riverbank and shoreline protection
Slope protection and rehabilitation

The system lends itself to providing an effective lining for river banks, canals, reservoirs and lakes. Under such circumstances it is essential to carefully design a suitable filter underneath each structure in order to prevent leaching of fine soil particles. Woven or non-woven geotextiles are considered to be most suitable.

Erosion at the toe of the bank is prevented by continuing the lining to below the anticipated depth of scour. Below the waterline, cells should be filled with coarse material and, above normal waterline, with topsoil. Graded rock or woven/non-woven geotextile filters are to be provided where necessary, to prevent leaching of fine soil particles.

3. Stormwater control and spillways: The elements are used for lining dam spillways and sloping weirs, storm water attenuation ponds or downstream aprons. They are also ideal for lining water courses of varying sizes from small ditches to large canals. In designing such structures a roughness coefficient of 0.04 (CERC 1984) has to be assumed.
Terrafix concrete block applications Terrafix concrete block applications
Dams and Spillways
Storm water control

Design Considerations

A feasibility study into the hydraulic applications of the TERRAFIX system by the division of Earth, Marine and Atmospheric Science and Technology of the CSIR has revealed very positive characteristics. A copy of this report is available on request. Information contained in this brochure is furnished as a guideline only. The responsibility for correct utilisation, design and construction shall rest with the controlling engineer or contractor. For best results and technical advice, contact our recommended contractors. For hydraulic applications, the CSIR can also be approached.  
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