A huge security wall, just under one kilometre long and up to 4.2m high, has been built with prestressed hollow-core panels manufactured by Echo Prestress, on the 640Ha Waterfall Estate in Midrand, currently under development by Century Property Developments.
Rising on the eastern perimeter of the property on gently sloping ground just above the Jukskei River, the wall forms a secure boundary between what will become a wooded parkland and a (yet to be built) public road.
The wall is an example of Echo’s full-service security-wall solution offering which involves column and foundation designs, civil and construction work and wall panel installation.
The Waterfall project was a joint venture between Echo Prestress, Encon and V-Con Civils and the wall was built in two sections, one at 540m and 3.6m high, and the other at 400m and 4.2m high. This height variance is not readily apparent to the naked eye, mainly because there is no stepping and the wall follows the natural slope of the land. To facilitate this, ground-level panels were cut at the same angle as the gradient.
The panels were secured between H-section galvanised-steel columns, which were bolted onto cast-in-situ concrete foundations. The columns were spaced at six metre centres allowing for 25mm installation tolerances on either side.
Echo Group marketing director, Melinda Esterhuizen, says there are several advantages to this type of walling, speed of construction and cost being major considerations.
“Eight to 10 bays or 48 to 60 linear metres were completed daily (eight hours). A conventional masonry wall would have taken two to three times as long with no advantage gained in strength or durability. In fact, because our panels have a compressive strength of 50MPa, they are virtually indestructible.
“The cost of building a security wall using prestressed hollow-core slabs is considerably more economical than an in-situ wall offering the same properties. Moreover, precast walling requires no shuttering or propping, onsite curing, formwork or grouting,” says Esterhuizen.
Commenting further Esterhuizen said that the Waterfall wall had added architectural features such as gabion cladding on the inner-facing steel columns, textured painting and the attachment of electrical wiring on top of the wall.