In construction, the evolution of retaining walls has seen a significant shift from the traditional use of poured concrete to the innovative use of concrete blocks; particularly high-performance Terraforce blocks. For years, the misconception that retaining walls (especially those exceeding heights of 4 meters) must be constructed with poured concrete has persisted. However, Terraforce blocks have demonstrated that they are not only viable but also preferable in many scenarios.
20.5m Terraforce round face finish wall stabilising cut and fill slopes for a road project.
Moving beyond poured concrete
Historically, retaining walls were almost exclusively made from poured, reinforced concrete. Despite the availability of concrete retaining blocks for decades; a lingering belief remains that blocks, especially hollow core units, are insufficient for high structures. Terraforce is disproving this notion with various high-profile projects worldwide, showcasing the extensive flexibility and strength of concrete block retaining walls.
One standout project is the Terraforce retaining wall at Palm Jumeirah in Dubai. Led by experienced engineer Simon Knutton from KCE Consulting Engineers, this project utilized over one million L16 rock face finish blocks, supplied by Terraforce’s licensed manufacturer, Consent Concrete Products. The success of this project underscored the viability of Terraforce blocks in demanding conditions, such as beachfront protection and aesthetically pleasing designs along Palm Jumeirah’s fronds.
Beachfront protection, Palm Jumeirah, Dubai. Over a million Terraforce blocks supplied
Breaking new ground: The potential of Terraforce Blocks
The question of how high composite retaining walls can go is determined by the expertise of design engineers. Simon Knutton emphasizes that while Terraforce walls can reach impressive heights, such as the 25-meter terraces at Ezulwini, Swaziland, caution and proper engineering are paramount. Walls exceeding 8 meters and with steeper angles often require additional reinforcement, such as double layers or concrete-filled blocks at the base, to prevent pressure cracks and ensure stability.
Impressive example of a large scale Terraforce retaining wall, Ezulwini, Swaziland, for the new International Convention Centre (ICC) commissioned by King Mswati III
Terracing: A solution with caveats
Terracing is a technique used to achieve greater wall heights by effectively reducing the slope angle. While it can be beneficial, Simon Knutton warns that improper use can surcharge lower walls. Therefore, spacing and reinforcement need to be carefully calculated.
Guidelines for safe construction
The construction of high retaining walls requires strict adherence to engineering guidelines. According to Silvio Ferraris of Remacon Products, any wall exceeding 1.2 meters in height, or 1.5 meters at a 70º angle, must be designed by a qualified engineer. He also stresses the importance of a solid foundation, adequate drainage systems, and proper compaction of soil to ensure the safety and stability of high walls.
Ferraris outlines several methods for building high composite retaining walls using Terraforce blocks:
- Double skin: This method increases wall mass and shear resistance.
- Geofabric: Tensile layers of geofabric can significantly enhance wall height by countering active soil forces.
- Concrete infill: This improves mass, shear resistance, and crush strength.
- Steel reinforcement: Essential for structurally integrating concrete-filled blocks.
- Interlocking keys: Useful for managing higher shear forces.
Case studies: Terraforce in action
Several projects illustrate the remarkable capabilities of Terraforce blocks:
- Monte Casino, Johannesburg: A 9-meter high wall completed in four months using Terraforce L13 blocks.
- Bishops Court, Cape Town: A 7.5-meter retaining wall supporting significant earthworks, utilizing geofabric and in-situ concrete keys.
- Nettleton Road, Clifton: A challenging 9-meter high wall designed for steep driveway access and reinforced with concrete columns and geofabric.
- Woodinville Athletics Club, USA: An 11-meter high wall designed to withstand seismic forces using Terraforce L13 blocks.
9m high Terraforce round face retaining wall built 2001 at Monte Casino, Johannesburg, South Africa
Expertise: The key to high retaining walls
Fred Laker from Icos Engineering, a veteran in Terraforce designs, emphasizes the critical role of experienced engineers in ensuring the safe and effective use of Terraforce blocks. The combination of innovative materials and expert engineering has allowed Terraforce to set industry standards and achieve unparalleled success in diverse environments.
Contact Information:
For professional advice and customized construction solutions using Terraforce products, reach out at [email protected].
Terrasafe aims to provide top-tier engineering and technical services, contributing significantly to sustainable construction worldwide.
