Terraforce segmental retaining walls were developed in the late 1970s to provide a more cost-effective and versatile method of retaining steeply contoured ground than was then available using conventional construction methods. Today, a range of modular retaining wall systems competes with reinforced concrete retaining walls. Most of these segmental retaining wall systems are quicker and simpler to build with and the retaining walls more interesting and pleasing to the eye.
Segmental retaining walls allow for the incorporation of gentle radiuses and 90? corners, as well as terraces, stairs and columns – details that are difficult and costly to build when using more conventional in-situ concrete construction.
For retaining wall designers, corners are of particular interest. Some systems offer corner blocks and others function as ‘one-block systems’ that cater for inside and outside corners without a specially designed corner block.
In South Africa, Terraforce pioneered the idea of the one-block system, which translates into low inventory requirements and simplified logistics. No corner blocks are required and this is reflected in the cost-effective nature of the system.
For the most part, by adjusting the horizontal interlock of each adjacent Terraforce block, the rounded outward facing curves can be placed to function as wide corners. Sharper outside corners are also possible, by positioning the blocks with the round face functioning as a soft corner. Inside 90? corners with the rock-face block are created by positioning the blocks to lock alternately, in zipper fashion. However, when the rock-face version is specified with precise 90? outside corners, it is necessary to cut and trim the selected blocks with an angle cutter to achieve a neat finish. Generally, those blocks are filled with concrete or mortar for added strength.
Corners and sharp curves then need to be stabilised, especially when they extend to heights of more than 1.5m. This can be done easily if geogrids are used in composite retaining structures – by overlapping the reinforcing grids with the backfill. Otherwise, 3 to 5% cement-stabilised sand can be specified for the backfill to strengthen an outside facing corner or a convex radius within a wall. Filling corner blocks with vertically reinforced concrete is another option.
Terraforce Retaining Wall Systems make it easy to turn the corner in retaining wall construction.