Pre-cast concrete wall panels help architect achieve a modern and sophisticated look

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Pre-cast concrete wall panels

The new six-storey 2Ten Hotel will open its doors in June 2018, by which time owner and developer, George Magwabeni, will have almost doubled available room capacity at the very popular EMM Convention Centre in Sibasa.

It is immediately noticeable by the slender and elegant vertical and horizontal lines that traverse the full length and width of the east, west and south walls of the structure. The look is enhanced by the rounded chamfers, as well as smooth and silky finish of each pre-cast concrete panel that makes up the façade.

Meanwhile, slender horizontal and vertical strips of pre-cast concrete coping on the perimeter of the north side seamlessly blend in with the exposed precast concrete columns and roof slabs, as well as other building materials, to complete the external aesthetics of the structure.

CoreSlab designed and manufactured more than 800 square metres of pre-cast concrete wall panels and coping for this project, and worked closely with the main contractor, Corestruc, in their installation.

The façade of the new structure was the most complex aspect of the entire construction programme, which has relied almost entirely on a bespoke pre-cast concrete system from the Limpopo-based company.

This is CoreSlab’s largest project, and its successful involvement in a number of private and public sector developments, including the New Civic Centre in Giyani and the large residence expansions at the University of Venda.

Magwabeni, a well-known entrepreneur in Sibasa and Thoyandou, was first introduced to the company’s modular construction system by structural engineer on this project, Paul Botha of VBL Consulting Engineers. Paul Botha worked with both CoreSlab and other CORE group companies on another successful project.

In addition to a durable build that would continue to add value for many years, the professional team, including Paragon Architects, agreed that the pre-cast concrete façade would help achieve the client’s requirement for a modern and sophisticated looking hotel.

This would ensure it merges with the existing hotel and conferencing sector that is connected to the new neighbouring structure via a short pedestrian walkway.

Importantly, a modular approach to construction would also overcome many of the complexities that would arise from using conventional in-situ techniques in an extremely congested site. In addition to the EMM Convention Centre to the right, the site neighbours another building expansion programme to the north. They encroach on the site boundary with merely a few metres distancing the west wall from the existing EMM Convention Centre.

A pre-cast concrete system eliminated the need to install and erect scaffolding, while doing away with large shuttering and formwork teams on site, as well as the complex co-ordination of building material deliveries.

Jaco de Bruin, managing director of CoreSlab, says the installation of the wall panels commenced once the bulk of the superstructure had been completed, and both contractor and supplier would have to maintain an efficient sequence so as not to delay the specialist trades.

“All the items were specially designed for this project, demanding utmost accuracy at the batching plant to avoid delaying the installation teams ad any wastage. This was initially a very complex undertaking that required ongoing refinement in the early phases. Despite a slow start in the beginning of the works, accuracies of between two millimetres and three millimetres were achieved by the installation teams on the façade,” De Bruin says.

Up to nine wall panels were delivered to site and installed in a day, considered an optimal construction sequence. They were dispatched by CoreSlab on a just-in-time basis due to the severely constrained working conditions. There was just enough space for the tower crane laydown area behind the structure, while deliveries would also have to be co-ordinated via the main entrance to the EMM Convention Centre.

In order to maintain a swift turnaround at the batching plant, a special self-compacting concrete mix was designed especially for this project and significantly accelerated production rates.

Precision in the casting process was also facilitated by the specialised forms that were imported from Australia.

As is the case on all of CoreSlab’s projects, a system of pre-checks and post-checks are undertaken throughout the production cycle, while sensors inside the sophisticated batching plant constantly monitor the temperature and moisture content of the concrete mix.

Only washed aggregates and sand from reputable suppliers enter the production cycle, while silica fume supplements a portion of the cement content to create a denser micro-structure of the concrete.

A separate steel-fixing yard ensures a high quality reinforcing in the concrete casing.

De Bruin says thorough planning right in the early design stages, also ensured a swift production rate on site. Meticulous attention was paid to the connection system that was designed and manufactured specially for this project to avoid unnecessary handling of the panels and coping, as well as the template to guide Corestruc’s installation teams.

They commenced with the bolting and grouting of the coping into the hollow-core slabs at each floor level of the structure which, in turn, support the large wall panels.

The items were lifted from the laydown area using a tower crane that was positioned in the middle of the site once the foundation to the structure had been cast by Corestruc’s teams.

Magwabeni is looking forward to opening the new hotel, which will also feature the same high quality facilities its visitors have come to enjoy over the years, including a bar, restaurant and gymnasium on the top floor, providing incredible views of the rolling green topography.

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