More than 80 high-quality pre-cast concrete bridge beams make up the superstructures of two new bridges over the Molototsi River that have brought urgent relief to poor rural communities in Limpopo’s Mopani District.
These two new structures have replaced old bridges that collapsed during extremely high rainfalls in 2014, leaving communities stranded for days on end.
The Roads Agency of Limpopo appointed Nyeleti Consulting Engineers to design the two new all-weather structures on roads D3212 and D3213 at Ga-Ntata.
Axton Matrix joined the professional team as the main contractor, which sourced high quality pre-cast concrete beams and side panelling for the bridges from Coreslab, a Limpopo-based pre-cast concrete specialist.
This single point of contact for all pre-cast concrete requirements also works closely with sister company, Corestruc, to quickly assemble the structures, ranging from civil-engineering infrastructure through to private- and public-sector property developments.
Jaco de Bruin of Coreslab, says the company has supplied M Beams, I Beams and T Beams, as well as F-type bridge barriers, or parapets to many bridge construction projects in the province.
“We broke into this market after our successful involvement in the Lawton Bridge construction programme in Polokwane,” says the managing director.
“Certainly, the R24,25-million road-over-rail structure provided ample opportunity for us to showcase our capabilities in the field. These included the high quality of the items and the efficiencies displayed by our teams in their installation. The project for the Polokwane Municipality opened many doors for this division, which combines the skills of both Coreslab and our sister company in bridge construction programmes.”
The main 96 metre (m)-long structure comprises 48 pre-cast concrete beams and the other 60 m-long bridge 36 units. Most of the bridge beams are 24 m long with some 27 m in length, and they vary between 50 MPa and 60 MPa.
The M-beams were pre-formed with holes through which transverse reinforcement has been installed to brace the structures. After their installation, the main contractor fills the spaces between each pre-cast concrete unit to produce a robust concrete slab.
De Bruin says Coreslab’s key differentiator is its focus on innovation, a process that relies on early involvement with engineers in the design and conceptualisation phases.
Batching of the items is undertaken by Corebatch, the production arm of Coreslab, with every item allocated an individual identification number to ensure tight control over quality before they are dispatched to site.
Meanwhile, close interaction is maintained with Corestruc’s team of assemblers to ensure timely delivery of the units using a dolly-bogie system that was designed specifically for the efficient handling of these heavy items on site.
Equipped with a special side loader, the technology does away with the need for two mobile cranes just to offload and place each item at the laydown stations.
In so doing, only one mobile crane was required to install the bridge beams on this site.
Rapid installation is also ensured by the extensive preparation activities that are undertaken by the teams ahead of installation.
Coreslab and Corestruc personnel arrived at Ga-Ntata earlier this year to start surveying activities once Axton Matrix had completed the abutments and piers, and installed the bearing pads upon which the bridge beams rest.
Using a 160 ton crane, Corestruc and Coreslab were able to maintain a steady production rate of up to six beams a day, although it has almost doubled production at other related projects.
De Bruin concludes that he is confident that the company will continue to make its mark as a key partner to government and its professional teams in delivering essential infrastructure in the province!