Client: Cape Concrete (PTY) Ltd
Consulting Engineer: Mowana Engineers (PTY) Ltd
Transnet SOC Ltd commissioned the construction of a third Iron Ore Tippler (Tippler 3) at the Port of Saldanha Bay, which forms the tail end of their Sishen-Saldanha iron ore railway link.
The construction of the new tippler structure, a bulk iron ore unloading facility, necessitated significant upgrades and realignments of the existing road and rail transport infrastructure that feed the Port of Saldanha Bay. This includes new road-over-rail bridges as well as the extension of an existing bridge to accommodate new railway lines and bulk material conveyor systems.
Cape Concrete (Pty) Ltd, was appointed by the main contractor to manufacture the post-tensioned precast concrete beams for two bridges. Mowana Engineers was in turn approached by Cape Concrete to provide alternative precast concrete beam designs that could offer cost and manufacturing time savings. A detailed analysis of the structures confirmed that a pre-tensioning system as an alternative to the original post-tensioning system was feasible, without amendments to the beam dimensions. In total 8 I beams and 36 M beams had to be manufactured with a total concrete volume of 520 m3 or a total weight of 1 360 ton.
Cape Concrete’s casting yard in Blackheath is equipped with a 40 m long stressing bed that is purpose made for the manufacturing of pre-tensioned concrete beams. A coal-fired steam boiler is used to produce steam for the concrete curing process and to accelerate concrete strength gain. A production rate of 1 beam every second day was achieved during the peak construction period.
The location of the casting yard relative to the construction site, 170 km away, posed interesting transport and logistical challenges, with some of the beams being 32 m in length and up to 50 ton in weight.
The project stands as a testament to engineering expertise and teamwork by all stakeholders involved, to deliver a quality product.