One of Sika’s innovative and environmentally friendly products came to the fore when a unique marine ecosystem was threatened by erosion.

Marine Biologists realised that an endangered area had developed on the south side of Richards Bay Harbour near Berth 208. Erosion of beach sand and soil was affecting the natural habitat of Mangrove trees which thrive in salty water and have the ability to grow where no other trees can. Mangrove swamps form the basis of a complex marine food chain and their coverage of coastal shorelines and wetlands provides a unique habitat for many diverse species of birds, mammals, crustaceans and fish. What made this particular region so rare was the fact that three different species of Mangrove were growing there.

In 2009 Transnet awarded Stefanutti Stocks/Stefanutti Marine the contract to build a breakwater 100 metres out to sea so that the destructive action of waves would occur further away from the affected shoreline. The breakwater was to consist of forty-four polystyrene pontoons, each measuring 15metres long x 5metres wide x 1.2metres high. Twenty-four segments of standard size polystyrene were required to make up one pontoon, which was subsequently encapsulated and then enclosed in a galvanized steel reinforcing cage. 50mpa of concrete capping was then poured into fixed shutters around the steel reinforcement. This combination of materials formed a floating reinforced concrete pontoon.

Subcontractors, Rodcol were responsible for waterproofing the pontoons. When the specification called for 3mm thick polyurea, the unequivocal choice was Sika’s high quality Sikalastic-841 ST, a two-part, 100% solids, pure polyurea membrane. It is extremely fast-curing, providing excellent corrosion protection and crack-bridging properties and is applicable in temperatures from 15°C to 70°C. Sikalastic-841 ST is highly versatile and may be machine sprayed onto concrete, steel and many other substrates.

Marine biologists specified black-coloured waterproofing for the polystyrene to ensure the pontoons blended in with their underwater surroundings and became part of the environment where various species of coral and marine plant life could eventually grow on the undersides. Once again, Sika came to the fore and supplied 28,000 litres of Sikalastic-841 ST in the specified colour.

The completed pontoons, weighing a total of 60 tons, were transported about 350metres to the water’s edge from where they were carried 100 metres out to sea via an anchor block and pulley system. To secure the pontoons in place, they were anchored to the seabed on concrete blocks lying parallel to the shoreline.

Following completion of this two year conservation project in which Sika played a key role, Transnet can feel confident that this unique area of Richards Bay will soon rehabilitate, enabling the natural habitat for plant and animal life to be restored.