One of South Africa’s largest steel manufacturers has ringed its Wadeville raw scrap processing plant with a formidable security wall made from toughened Echo prestressed hollow-core concrete panels – and in the process completely eliminated costly losses from scrap theft.
The huge wall, 1,2km long, 4,2m high and topped with a 500mm steel palisade, forms a virtually impregnable barrier surrounding the plant.
“The company was experiencing problems with theft of scrap, but that’s been reduced to absolutely zero since the wall went up,” says Echo Prestress marketing director Melinda Louw. “Intruders cannot climb over it, dig under it or break through it without making a great deal of noise – and taking a very long time,”
Construction of the wall, which took five months, was a combined operation involving five companies – designers, engineers, installation and grouting teams from Echo Prestress working alongside professional teams from project engineer ENCON, ARQ geo-technical consulting engineers, VNA piling specialists and CII Construction.
“Various ways had previously been tried to keep the thieves out, including conventional precast concrete panels and palisade fencing. But since the wall went up last May there has been not one incident of theft,” Ms Louw reports.
Preliminary tests were carried out to demonstrate the deterrent strength of the slabs. A five-man team armed with a jack-hammer worked all day to try to break through it, and failed. The wall was pronounced “rock-solid.”
A total of 850 Echo slabs of 150mm depth and a compressive strength of 50 MPa, were used in the project, each planted to a foundation depth of 0,6m, supported by steel columns. Securing the foundations was a major project in itself, according to Andreas Rehwinkel, a director of ENCON, which coordinated the structural and operational aspects of the project.
“The wall is a huge, heavy structure,” he said. “Soil conditions were not good, and we also had to consider the effect of high winds. In the end we used piling to secure the foundations.”
A key to the success of the building operation was “very close team-work and the meshing of skills of the design, engineering and construction professionals every step of the way from the Echo factory floor to the planting of the final slab in the wall,” said Echo Group technical director Daniel Petrov. “It was a prime example of Echo’s ‘complete package’ of not simply supplying the panels, but bringing its know-how aboard into the actual project itself.”
The wall panels and steel columns are fully recyclable. There is minimum waste in the manufacture of the panels, which consumes far less raw materials than conventional in-situ concrete. All waste concrete from Echo’s hollow-core operations is crushed and used in the manufacture of other products.