20 September 2010



echnicrete’s precast Enviro-Wall blocks – known for their ability to dampen traffic noise - were the preferred engineering solution for a retaining wall at a new onramp on the R21 highway interchange skirting close to houses in the Monument Park suburb.


Enviro WallExcavation work on the highway road-works, linking OR Tambo Airport and Pretoria, created a steep embankment requiring a retaining wall that was structurally sound, environmentally friendly and aesthetically pleasing. A total of 26 800 of the stacked interlocking blocks were used to build the 326m-long wall, which reaches a maximum height of just under 5m.


Enviro WallEnviro-Wall produces a variety of visual effects, with gaps for vegetation growth or as a solid engineering structure. Engineers opted for a solid face, and the completed structure features an attractive checkerboard pattern achieved by using alternate ridged and smooth surface patterns.

“The very attractive aesthetics of the finished wall, its fine engineering qualities and ease of assembly were among the reasons why the Enviro-Wall system was chosen,” says Dawid Els of Pretoria consulting engineering company Nyeleti Consulting.



The wall was constructed vertically, with a back-fill of low-fines to give added strength and aid filtration. There were good reasons for not adopting the conventional 70 or 75-degree building angle: space-saving and the proximity of storm-water, electricity and water lines.

“The result is an unusually attractive off-ramp feature and an engineering solution that has worked very well,” says Els.