Supplied by Concor
Racing to meet the new intake of university students for 2023, leading black-owned contractor Concor is keeping up the pace on the 13-floor Apex Studios building in Braamfontein. Final concrete pours were recently completed ahead of schedule on the top floors, according to site agent MacDonald Ngobese.
In the busy and space-constrained urban context of Braamfontein, Johannesburg, Concor is making rapid progress on Apex Studios, soon to provide 899 rooms of much-needed student accommodation.
Apex Studios, initially known as The Groove, is an ambitious 13-storey building comprising two adjoining blocks. Conveniently situated across the road from Wits University, the site presents various space challenges which Concor deals with in its daily programme. These constraints, combined with the tight completion schedule, have meant that there is activity around-the-clock on the project.
Built on pile caps of up to three to four metres in depth, Apex Studios is an L-shaped structure with the two blocks joined on each floor. Short outdoor bridges and balustrades between the blocks let in fresh air and sunlight. During construction, three loading platforms have been deployed on each building to facilitate the safe delivery of materials by crane. Designed and approved by structural engineers, each platform takes up to 2,3 t of material and is load-tested before use.
“Having two tower cranes – one 60 m jib crane and one 40 m – on site has helped us expedite the safe movement of material,” says Concor site agent MacDonald Ngobese. “The 40 m crane works two 12-hour cycles, including the placement of material by the night-shift team on the respective levels of the building for the following day’s activities.”
Use of readymix concrete is helping to speed up the construction and bricklaying process, while also ensuring a consistent colour of concrete in the jointing. Three readymix deliveries of 6 m3 each keep the site supplied, says Ngobese, with retardant admixtures extending the setting time and reducing wastage.
The building includes 16 sheer walls comprising Class 2 off-shutter concrete, completed to a high standard, he notes. New formwork is being utilised along with oils to prevent sticking, creating an attractive and durable finish. While the formwork was contracted out, Concor completes the columns and sheer walls in-house, placing concrete from a bucket conveyed by the tower crane.
“Concrete slabs have been constructed in partnership with a supplier who provides and fixes the rebar, and another who pumps the concrete to where it is required,” he says. Concrete is moved from ground to Level 8 with a mobile boom pump, and from Level 8 to the roof with a static pump. The slab on each level – for both block 1 and 2 – consumes about 300 m3 of concrete. The whole project will use around 6,200 m3 of concrete, with 2,300 m3 being dedicated to the slabs and the bulk for the vertical elements. The mass of reinforced bar being used totals 160 t.
The face brick finish makes for an attractive surface while needing no plastering and minimising long-term maintenance. About 1,5 million bricks will be used during the project, including internal brickwork and the face brick façade. Ngobese explains that steel frames have been used for the window apertures, as this speeds up the work of the window installers. Bricklayers build these frames into the brickwork, so that no measuring up of each frame is required later.
“This approach has allowed all the aluminium window frames to be manufactured in advance, to be ready for a rapid installation schedule of about 40 frames a day,” he says. “All the necessary tolerances have been built into the measurements, so no time is lost.”
An interesting aspect of the project is the heritage value of the existing buildings, which are being preserved as part of the Apex Studios precinct, and repurposed as the common area space of the development.
“We are working according to a comprehensive heritage report that specifies what aspects of the buildings need to be conserved,” he says. “For the original slate roofing, for example, we have contracted a specialist to advise on the cleaning and restoration.”
As usual, says Ngobese, safety is always a priority – both for workers on site and for the public. This is particularly the case on this site, which is closely bounded on three sides by roads. The M1 highway, perhaps Johannesburg’s busiest north-south route, is just 1,2 m from the building’s western edge.
“Safety measures are stringently applied while keeping deliveries streamlined within the limited available space around the buildings,” he says.
Concor was able to secure wayleaves on Enoch Sontonga Avenue and De Korte Street for off-loading and laydown of materials. Managing the busy traffic is therefore vital, and four flagmen have been ensuring safety on this front. Cranes are also not permitted to slew any load above the roadways.
“Scaffolding with shade netting is installed continuously behind the top level of the building, about a floor below the live deck,” he said. “That is an important way of preventing the possibility of a falling object landing on a road or highway.”
The priority of safe working is implemented through the constant reinforcement of an on-site safety culture, he says. This is driven home by three full-time safety officials, and multiple safety inspections each day. This has ensured that – even with 40 contractors and over 300 workers on site – there have been no lost time incidents on the project. By late-August, this meant over 500,000 LTI-free hours.
Alongside safety, the site has also implemented health strategies including dealing with dust. Among the typical causes of dust is the use of angle-grinders to chase into walls for services installation. Ngobese explains that this is minimised through the use of vacuum-bags on grinders, as well as pre-dampening of walls. Concor will take the building through to fit out stage, which will include furniture and a fridge in each room. When completed, Apex Studios will offer 325 units, each comprising a combination of one, two, three or four bedrooms. The project is aiming for handover to the client in November 2022.