Tag Archives: Concor

CONCOR HANDS OVER HIGH SPEED IKUSASA PROJECT AT OXFORD PARKS PRECINCT

Applying innovative construction methods and its well-established quality and scheduling systems, Concor has met another tight deadline with the handover this February of the Ikusasa building in Rosebank, Johannesburg.

The building – which features four storeys above ground and three basement levels – is part of the popular Oxford Parks mixed-use precinct in Johannesburg, and will be occupied by Anglo American Global Shared Services (AGSS). According the Concor site agent Warren Mills, the company’s core team was required to manage around 70 specialised subcontractors, ensuring the most efficient deployment of resources to meet the project’s demanding timeframes.

“Among the innovations we employed to cut the construction time was the use of larger foundation piles,” says Mills. “This meant that there was no need for concrete bases or excavating around each pile; instead, the design allowed the columns to be cast over the piles.”

Some 115 piles were cast, with columns spaced on an 8.4 metre by 8.4 metre grid to hold the suspended concrete slabs. By expediting this part of the contract, Concor could give early access to the wet trade contractors like bricklayers and tilers, as well as to the installers of the unitised façade panels.

“This allowed us to make rapid progress toward the external works and the internal fit-out,” he says.

Another innovation was to back-prop on just two levels rather than the traditional three levels. This also allowed earlier access to the lower floor plate, to initiate brickwork and ‘first fix’ services such as floors, ceilings, electrical supply cables and water pipes.

“The result was to facilitate beneficial occupation for the tenant, giving them early access in a phased approach to prepare the working areas with furniture and other fixtures in time for employees to start work,” says Mills.

The building’s four levels make up over 7 500 m2 GLA, while the three basement levels cover more than 10 300 m2. The structure consumed about 8 700 m3 of concrete and over 800 tonnes of reinforced bar.

In line with sustainable building practice, a priority on the site was reducing, re-using and recycling construction waste. This included separating waste at source, ensuring that rubble, wood, steel and plastic was sorted into dedicated skips. By preventing contamination of different waste streams, waste could be more efficiently and cost effectively recycled.

Ikusasa is Concor’s first 6 Star Green Star building in terms of the Green Buildings Council South Africa’s Green Star rating. In recent years, the company has completed a number of award-winning buildings in the Oxford Parks precinct.

MILESTONE AT MSIKABA PROJECT WITH JACKING OF SOUTH PYLON LEGS

The Msikaba Bridge Project on the new N2 toll road between Port Edward and Umtata achieved an engineering milestone this month, as the legs of the bridge’s south pylon were hydraulically jacked apart.

The 580 metre long, stay cable bridge – which will span the 198 metre deep Msikaba Gorge – forms part of the N2 Wild Coast project being undertaken by the South African National Roads Agency Limited (SANRAL) and is under construction by the CME JV joint venture, a partnership between Concor Construction and MECSA Construction.

These two legs make up the first 20 metres of the inverted Y shaped pylon, says CMEJV project director Laurence Savage, and are built without any lateral support as free cantilevers. Once completed four lanes of vehicles and a pedestrian walkway on either side will pass beneath these legs at the start and end of the bridge deck.

“The jacking apart of the legs countered the bending moment at the bases of the cantilever legs,” says Savage. “In layman’s terms, the jacking eradicated the effect of the legs bending towards each other; as engineers would see this, the legs are effectively vertical due to the jacking process.”

The bridge includes two pylons that will stand 128 metres high on each side of the gorge; the pylons support the bridge deck using a network of 34 cable tendons strung through their upper reaches.

“These cables then run from the top of the pylons back into anchor blocks located 100 metres to the rear of the respective pylons,” he says. “Each of the four anchor blocks is made up of over 1,600 tons of structural reinforced and mass concrete and extend 17 metres – the equivalent of six storeys of a building – into the ground.”

He explains that the lateral support was installed on the sixth lift of the pylon structure, after 520 cubic metres of concrete had been poured to reach a height of 20 metres.

“Two sets of hydraulic jacks were installed in parallel to each other and a jacking force of 1,750 kilonewtons (kN) applied to the two pylon legs to counter the bending moment for the freestanding cantilever legs,” says Savage.

“To achieve the required force, the two 150 ton hydraulic jacks were loaded to 90 tons, developing a pressure of 41 megapascals (MPa). The jacking was done on 5 MPa intervals, and deflections of the structure were monitored using dial gauges and surveying.”

He notes that a key consideration was the punching force on the flat face of the pylon legs due to the jack load. This also dictated the size of the bearing plates affixed to the inside of the legs, enabling a dissipation of the force across the appropriate surface area. This avoided any damage to the structure due to loading of the concrete surface.

“The jacks only have a 50 mm stroke, which required the installations to be exact – as the 41 MPa pressure had to be achieved before the jack ran out of stroke length,” he explains. “The base plates were installed on the pylon leg structure with 29 mm non-shrink grout minimising the use of the stroke length.”

After the lateral support was aligned and seated, a grout biscuit was cast which served two key functions. Firstly, it absorbed any tolerances in the installation after the initial base plate installation and secondly, it assisted with the removal of the lateral support. Breaking out the grout biscuit released the pressure in the lateral support, once the seventh lift was cast and the legs permanently locked together.

“The temperature of the pylon structure and lateral support was measured to ensure an average of 22°C, to limit any unforeseen changes in force due to changes in the temperature during the construction cycle casting lift seven,” he says. “The lateral support was wrapped in a 25 mm thick thermal blanket to limit temperature change movements and any resulting changes in prop forces.”

The lateral support was locked into place using a two-part system: the locking ring on the hydraulic jack, and the locking ring on the super-shore jack housing. The preparation for the jacking took three months of planning and analysis, while the setup was conducted over nine days. The actual jacking process was complete in less than eight hours from commencement.

Savaged concludes that the total movement of the pylon after jacking totalled 23 mm at a force of 1,750 kN – which was within the design parameters. The casting of lift seven to lock in the release of the moment will be complete by mid-April.

CONCOR BUILDS TO TOP-LEVEL GREEN RATING AT IKUSASA

Its commitment to Zero Harm and sustainability ideally positioned Concor to complete the Ikusasa office block in Rosebank’s Oxford Parks precinct to 6-Star SA Office V1.1 green standards. 

According to Concor contract manager Martin Muller, the company has constructed a number of buildings in this development and elsewhere to 5-Star Green Star SA level in terms of the Green Buildings Council South Africa (GBCSA) certification. Ikusasa will be the first one of its projects to achieve a 6-Star Green Star SA Office V1.1 design certification. Green Star certification is an internationally recognised mark of quality for the design, construction and operation of buildings, interior fitouts and precincts.

“Concor’s strict performance strategies to manage water use, energy consumption, process waste and pollution all contribute to upholding critical environmental standards,” says Muller. “In addition to carefully applying our client’s sustainable designs, our quality systems all contribute to the points requirement in the GBCSA rating.”

These included Concor’s application of a comprehensive Environmental Management Plan on site, in line with its ISO14001 accreditation. It also applied a rigorous Waste Management Plan, which saw 70% of demolition and construction waste being re-used or recycled rather than going to landfill.

“We also conducted a hazardous materials survey on the project site before demolishing existing buildings, in accordance with the Occupational Health and Safety Act and other legislation,” he says. “Wherever we found asbestos, lead or polychlorinated biphenyls, these substances were responsibly removed as the law required.”

Annelide Sherratt, head of department for green building certifications at Solid Green Consulting, notes that four key members of Concor’s site team completed the Green Star online course – which helps the team understand and apply sustainable ratings on the project. Sherratt highlights that the Green Star certification focuses on nine categories of sustainability achievement, from management and materials to the reduction of energy use, water and emissions. 

“In terms of the materials category, for instance, the Green Star rating rewards developers and contractors for reducing the amount of natural resources used, and for reusing materials wherever possible,” she says. “At the Ikusasa project, Concor reduced the portion of ordinary Portland cement used in their concrete mixes by 30% as an average across all concrete mixes used in the project, and achieved a level of 60% recycled content in the steel requirement.”

Local sourcing of materials also played a role in this category, where Concor sourced 20% of the contract value from suppliers within a 400 km radius of the site, and 10% within 50 km. 

In terms of energy efficiency, Ikusasa aims to achieve a Green Star SA Net Zero Carbon Level 1 – by generating as much energy on site as the base building would require. This includes the use of a photovoltaic solar generation system on the roof of the building, producing renewable power. The building’s design and operation enhances energy efficiency by applying sub-metering to track and control the main areas of consumption.

“Any energy uses of 100 kVA or more are metered separately so users can benchmark usage targets and implement opportunities to reduce consumption,” she says. “This impacts on the production of greenhouse gasses and other emissions associated with electricity generated by fossil fuels.”

The data generated by the metering system is captured and analysed by a digital monitoring system for building management, but is also shared with the building’s tenants and visitors on a public display screen – aimed at raising awareness and driving energy-efficient behaviour. 

Conserving water is another important element of the building’s environmental performance. This is optimised using options like low-flow tap fittings and dual flush toilets, as well as water sub-metering for uses such as irrigation and bathrooms. Plant irrigation was reduced by 50% using water-wise irrigation methods and smart sensors. Also, the heating, ventilation and cooling system is cooled by air rather than by water. 

CONCOR STARTS WORK ON FAST-TRACK STUDENT BLOCK 

Leading black-owned contractor Concor is hard at work on the latest student accommodation project in Braamfontein, Johannesburg – a much-needed contribution to the national shortage of these facilities.

The Groove, a substantial 13-storey development, will provide space for 899 students, and is conveniently located just opposite the South Gate of Wits University. Concor is working with developer Growthpoint Properties, who in turn is operating on behalf of Durban-based fund manager Vulindlela. 

In addition to the new build, the project is also repurposing some of the existing buildings on the site where the old Doves & Kloppers funeral parlour became a familiar landmark on the busy Enoch Sontonga Avenue. These existing buildings will provide additional services and utilities for student residents.

The fast track venture is scheduled for completion in just 12 months, according to Concor site agent MacDonald Ngobese, and began in November 2021. 

“Concor has a well-established reputation for delivering complex projects speedily and on budget, while still being highly competitive in terms of costing,” says Ngobese, “This places us in a strong position to win projects like this.”

He notes that the successful completion of fast track projects relies on having a highly skilled and experienced core team on site, to closely manage subcontractors and to keep strictly to the construction programme. This also requires constant and in-depth communication with all stakeholders, from the client to operational partners and local authorities.

“The scope of the work includes full fit-out, right through to joinery,” he says. “Among the challenges is the very constricted work environment, as the site borders busy urban roads and the M1 highway.”

Two of Concor’s tower cranes have been erected on site to help deal with space constraints and to expedite the movement of materials in the interests of a fast pace of construction. While one crane is working 13 hours a day on production work, the second is speeding up the off-loading and placement of material deliveries. 

CONCOR PROGRESSES WITH MAJUBA ASH DISPOSAL FACILITY

Leading black-owned contractor Concor is over halfway with extending the continuous ash disposal facility (ADF) at Eskom’s Majuba power station near Amersfoort in Mpumalanga. This project will ensure that Majuba can continue generating electricity while complying with ever-stricter environmental regulations regarding the responsible storage of waste.

According to Mabandla Dlamini, contracts director at Concor, the extended ADF will accommodate ongoing ash generation at the power station until February 2036. The project is being conducted in a fully-integrated joint venture with Midrand-based contractor Lubocon Civils, with an 85%:15% split with Concor holding the major percentage.

To date, Concor has handed over Terrace 2A and is in the process of handing over one of the two rehabilitation dams, says Dlamini. The construction of the extensive terraces – which measure 1.2 km long by 175 metres wide – began with bulk earthworks, cutting down to a design level before constructing the various layers. 

These layers include 100 mm of filter sand, followed by a Class 2 geomembrane and two 150 mm layers of clay. This is covered by a double-textured 1.5 mm HDPE geomembrane, followed by a 300 mm coarse ash layer. Each liner terrace, constructed from stabilised ash, is broken down into compartments of 5 metre widths, located every 100 metres.

“Underneath these layers, we are constructing a network of herringbone subsoil drains with a leachate collection system which will flow into a pollution control dam,” Dlamini says. “This will drain into Pollution Control Dam 5.”

Specialist sub-contractors have been used for the all-important lining beneath the dams, as well as the identification of any potential leaks in this lining. 

“The excavation and bulk earthworks for the pollution control and rehabilitation dams is followed by the construction of a subsoil drainage layer,” he says. “In addition to the geomembranes and layers of filter sand and impermeable clay, this layering includes 250 mm thick geocells, a ballast layer comprising 300 mm thick cement-stabilised sand (8% by mass) and geocells.”

The rehabilitation dams also have penstocks and valve chambers. Enhancing the environmental controls are water perimeter canals around the whole facility to separate and channel clean and dirty water. These are lined with 100 mm geocells filled with 30 MPa concrete, controlling the stormwater in the area. 

“The canals play a vital role in reducing the risk of any washdown from the tailings facility,” he says. “Measuring up to 7 metres in width, the total combined length of these canals will amount to more than 4 km.”

Some 1,400,000 m3 of earth is being excavated during the project, while the linings include 860,000 m2 of double-textured 1.5 mm high-density polyethylene (HDPE) liner. The stabilised ash layer will require 130,000 m3 of ash sourced from the power station and screened to prescribed specifications before being mixed with stabilising cement.

For the concrete work – which will include structural concrete for silt traps, spillways, drains and culverts bases – a total volume of 14,000 m3 of concrete will be used. Some 7,700 tonnes of cement will be delivered in bulk, to be stored in Concor’s on-site silos at its batch plant.

Site agent, Muhammad Asmal says that at project peak there will be almost 90 items of earthmoving equipment on the site. This will include 40-tonne articulated dump trucks, 70-tonne tracked excavators, tipper trucks, pug mills, screening equipment, graders and compaction equipment. 

“There are 43 subcontractors and suppliers engaged in the project,” Asmal says, “with over 440 personnel employed on site – 285 of them from local areas.”

The Concor-Lubocon JV is also constructing 5.5 km of internal or monitoring road, with G5 and G7 layers from commercial sources in Newcastle and Ermelo respectively. 

“As part of Eskom’s commitment to supplier development and localisation, a Supplier Development Plan was developed in conjunction with the Concor Lubocon JV to facilitate the inclusion of SMEs and QSEs from various towns surrounding the Majuba power station,” Nielesh Maistry, Eskom projects manager, says. “This included areas in the Gert Sibanda Municipality. “

SD&L manager, Nkateko Rasimphi highlights that the Concor Lubocon JV takes a proactive role in the training and induction of small and medium-sized enterprises (SME), especially with regard to issues such as legal liability, hazard identification and risk assessment.

“We have identified local technicians who we will help to develop, with the objective of training them and putting them on the road to professional registration,” he says. “The JV also runs a corporate social investment programme with local communities, focused on educational infrastructure in previously disadvantaged schools.”

Complying with strict environmental regulations means ongoing monitoring on site, according to Portia Rasakana, Lubocon’s environmental manager at the Majuba project. She highlights waste management as a key focus to avoid any environmental impact, but concerns such as pollution and dust management also receive constant attention.

“It is crucial that all our employees and subcontractors are conversant with the conditions of our Environmental Management Programme and our Water Use Licence,” says Rasakana. “This means building awareness among all our partners, and following up with strict enforcement.”

She notes that alien vegetation is also a concern, especially in areas where ground is disturbed. Management plans are in place for all environmental issues including waste, water and hazardous materials, she says. 

CONSTRUCTION OF THE MEERKAT EXTENSION GETS UNDERWAY

Concor, the leading black-owned construction company, in partnership with OptiPower, is building the foundations and infrastructure for 20 more dishes for the pioneering MeerKAT radio telescope. A precursor to the Square Kilometre Array (SKA) – which will be the world’s largest radio telescope – the MeerKAT project has already allowed astronomers to deliver unprecedented results. 

Its remote location in an arid area about 90 km from the town of Carnarvon is perfect for its purpose, providing a ‘radio controlled ’ backdrop for the mid-frequency array that enables the SKA’s work. According to Concor contracts manager Stephan Venter, the team commenced with the construction works on site in September 2021.

“With the piling rig on site, October saw our first piles drilled and concrete poured,” says Venter. “Soft soil and sandy conditions require that the 20 foundations will be based on piles with a concrete cap; each of these foundations has eight piles of 750 mm diameter and between seven and eleven metres deep.”

He highlights that precision is critical to the foundation construction, particularly the positioning of the bolt cage onto which each antenna pedestal is secured. These have to be accurate within fractions of a millimetre, to avoid any deflection when the dish ‘looks’ millions of light years into space.

“In addition to the accuracy, the foundations must ensure that the antennas are able to resist the force of winds, especially as the dish has a wide surface area,” he says. “There is also no room for any vibration of the dish.”

The 1,7 metre-tall, galvanised bolt cages – constructed to specification locally – are carefully positioned on the blinding of the foundation cap before the rebar armature is assembled, the shuttering is installed and the concrete is poured. After the pour, the top of the bolt cage extends from the foundation for securing the dish pedestal or tower.

Among the specific challenges of this project is the strict requirement to limit any radio frequency interference (RFI) in the vicinity of the MeerKAT telescope array. The highly sensitive radio telescope equipment is designed to detect extremely weak radio signals from astrophysical sources, and can be easily damaged by RFI from vehicle electronics, cellular phones and a wide range of other tools and equipment. Concor’s offices, workshops and laboratory are therefore in Carnarvon, and site personnel must travel each day.

“We have tested and modified all our on-site equipment to comply with the RFI limitations,” he says. “This includes excavators, trucks, graders, compactors, telehandlers, water bowsers, TLBs and our specialised concrete batching truck.”

The Reimer concrete truck is a self-batching unit chosen to do the work of a conventional batching plant, which in this instance was not justified by the relatively small volumes of concrete required. With 19 mm aggregate and crusher dust transported from De Aar, cement from PPC and tested water from local boreholes, concrete can be mixed in the truck on each foundation platform. The 20 smaller, piled foundations each take 60 cubic metres of concrete, while the larger four foundations each consume 144 cubic metres. 

“We are also employing a recycler on this project to prepare the wearing course layer for much of the 40 km of gravel access roads,” says Venter. “This allows us to save water in this dry area, as the recycler introduces water into the layer and then closes it up – keeping the moisture in for longer.”

The machine can cover long, straight sections of road efficiently, preparing the way for the grader to level the surface before final compaction. Concor will also excavate and fill 70 km of trenching, for electrical and data cables to run from the antennae to the Karoo Array Processor Building (KAPB). The project is due for completion by September 2022.

CONCOR RECOGNISED FOR EXCELLENCE AT BEST PROJECTS AGAIN

Concor Construction has been recognised for excellence at the Construction World Best Projects 2021 Awards with two of its projects each receiving an award. 

While both projects entered are quite different, the hallmark of quality construction underpinned both. The Radisson RED hotel in Rosebank, Johannesburg received a Highly Commended in the AfriSam Innovation Award for Sustainable Construction category, while the 300 bed Covid-19 facility at the Jubilee Hospital site north of Pretoria in Hammanskraal received a Special Mention in the Building Contractors category. 

Situated in the vibrant Oxford Parks mixed-use precinct in Rosebank, the contemporary 222 room Radisson RED hotel was designed to meet a minimum 5 Star Green Star Custom Hotel rating. The base build spec was provided by dhk Architects, while the interior design spec was by Source IBA. Concor took the project through to furniture, fitting and equipment (FF&E) stage including beds, chairs, television sets and the physical backbone for Wi-Fi connectivity.

With its architecturally compact design which incorporates functionality on an optimised footprint, the hotel comprises seven levels on top of a ground floor as well as a roof level for plant and services. It is a concrete structure based on conventional and post-tensioned slabs with grids to suit the room sizes. 

Radisson RED is committed to sustainable design and the hotels contains numerous elements underpinning its 5 Star Green Star Custom Hotel rating. This rating recognises that the building demonstrates “South African excellence” and is a step above the Best Practice level. 

The fast-track construction on the Jubilee Hospital project saw it being handed over to the Gauteng Department of Health just five months after work began in November 2020. Selecting alternative building technology enabled Concor to speed up construction without compromising the standards demanded by a world class medical facility. 

Concor used a modular approach in its construction plan, with units completed and put into operation while others were still being constructed. To suit this rapid roll-out, it was crucial wet services and ventilation systems were carefully selected as all mechanical services had to be commissioned on a standalone basis. 

Concor demonstrated its commitment to socio-economic development on both projects with a focus on upskilling small local business at the Radisson RED project and employing more than 230 local unskilled and skilled individuals from Hammanskraal at the Jubilee Hospital Project. 

MANAGING CONSTRUCTION WASTE IS PART OF GREENER FUTURE

Climate change is now everyone’s concern, and black women-owned construction leader Concor’s efforts to operate more efficiently and sustainably include the way it deals with its construction waste. 

According to Leah Nwedamutswu, quality assurance and quality control (QA/QC) officer at Concor, the company’s commitment to Zero Harm embraces staff, the community and the environment. Growing awareness of climate change imperatives has led the company to develop performance strategies to carefully manage water use, energy consumption and process waste. 

“This includes preventing pollution emanating from our industrial processes, which means spreading this message to all staff and subcontractors on our project sites,” says Nwedamutswu. “Our critical environmental standards are in place, and we actively assess and manage our risks and opportunities.”

The environmental management plans (EMPs) and authorisations of Concor’s clients are also embedded in the daily work processes, ensuring that the company can play its role in supporting the client’s compliance responsibilities. 

This commitment has recently been expressed by Concor at its projects in the Oxford Parks mixed-use precinct in Rosebank, Johannesburg, where it is proceeding with its sixth Green Star-rated building. Nwedamutswu highlights the company’s waste hierarchy system, which it has applied over the years to ensure that waste is effectively reduced, reused and recycled. 

“We have a detailed and ongoing focus on the natural resources that we consume in construction, and recognise that these are finite and precious,” she says. “The care with which we manage our waste also enhances health and safety on site.”

The waste management system prioritises separating the waste at source, and dedicates human resources to ensure that building rubble, wood, steel or plastic is properly sorted and placed in the right containers or skips. This prevents contamination of the various waste streams, allowing each stream to be more efficiently and cost effectively recycled.

“Implementing our system requires both discipline and education, especially as we employ many smaller companies as subcontractors, who may not initially give the same priority to environmental protection,” she says. “We therefore actively communicate our policies and requirements, and expect our partners on site to be as serious about waste management as we are.”

Specialised recycling service providers play an important role in Concor’s waste management supply chain, as they help to optimise the levels of waste that can by recycled. 

Dumping in landfill is considered an absolute last resort, and this must be kept to a minimum. Even building rubble can be pulverised and re-used in certain applications, as long as it is not contaminated by other materials. 

“Our strict policies require that we also monitor the integrity of our waste supply chain, to confirm that the various streams of waste actually go where they are supposed to,” says Nwedamutswu. “This is done by double-checking the weighbridge documentation we receive from our waste service providers, and these must match our own records of waste leaving the site.”

CONSTRUCTION OF ANGLO GLOBAL SHARE SERVICES’ IKUSASA BUILDING ON TRACK

Having excelled in recent years at management of fast track construction projects, Concor is again leveraging its depth of skills successfully – this time with Anglo American Global Shared Services’ (GSS) Ikusasa building in the Oxford Parks precinct in Rosebank, Johannesburg. 

Warren Mills, site agent at Concor responsible for the project, says that fast track construction has become increasingly prevalent as it allows occupancy within a shorter period of time from the decision being made to begin construction. 

“It does, however, require a more agile approach to construction especially as this type of project is far more complex with numerous subcontractors interfacing on a tight construction programmes,” he says. “On the Ikusasa project we will eventually have more than 70 subcontractors on site, and this is in addition to our own team of core disciplines. So it is all about tight control over scheduling and close co-ordination with all.” 

Commenting on the pace of construction, Mills says that bulk excavations for the three basement levels started in January 2021, and the concrete structure for the four storey building topped out in August. 

Given the construction schedule the decision was made to increase the size of the foundation piles allowing the columns to be cast over the piles. Mills explains that traditionally one would excavate around the pile and cast a concrete base or pile cap on top of the pile, however by increasing the size of the pile the need for concrete bases was eliminated, resulting in a time saving to the project. In total 115 piles were cast. 

Once the piling subcontractor had cast the piles, Concor inserted the column starter bars into the concrete whereafter the normal shuttering process was followed, and the concrete columns cast. Columns were spaced on an 8.4 metre by 8.4 metre grid, and decking was installed for the suspended concrete slab pour. 

The basement level pours were split into five separate pours to accommodate the construction schedule and allow other ongoing work to done. There are three full basements levels with a fourth smaller ramp connection to a future phase. 

Space constraints as well as financial feasibility informed the decision to go with a readymix service provider, and this decision formed part of the overall risk management on the project.

“The concrete design mixes for various aspects of the build including all slabs considered the need for a low carbon footprint with a low Portland cement content being used, seeing this fall into the green concrete category,” Mills says. “However, in the case of the column mix this was superseded by the need for an early high strength concrete that would facilitate the ongoing fast track construction process.”

Construction of the top structure continued with the building of a double volume space between the ground and first floors and the three office levels above that. The fourth slab was poured in mid-August to close off the third office floor. 

“Traditionally when constructing an office building, we would require three levels of back prop and support work, however on this project we managed to engineer a solution that required only two levels of back propping. Adopting this innovative construction methodology facilitated an earlier access state for subcontractors to start façade installations, wet work services and follow-on trades,” Mills says. 

Close collaboration between Concor and the client from the start of the project made it possible to accelerate long lead trades facilitating a more integrated approach with significant savings in time enabling the fast track programme to stay on track

A significant advantage is that the same engineering firm has been used for both the structure and the façade for the curtain wall. This allowed the design and manufacturing of the elements for the façade to begin while the contractor was still busy constructing the concrete structure. Accurate dimensioning of the façade was possible using sophisticated software that allowed modelling of the full façade around the concrete structure. In adopting these approaches, Concor unlocked two long lead materials, being the glass and façade tiling. 

The façade itself is a unitized system which is less labour intensive to install, and also does not require a full façade scaffold for installation. Both these will also contribute to cost and time savings on the project. 

Mills explains that Concor’s scope of work on the Ikusasa project includes the fit-out of the entire building, and this will see the company co-ordinate the installation of all fittings and fixtures before handover of the building to AGSS at the end of January 2022. 

CONCOR’S INNOVATIVE PAARL ROCK SHOWS THE WAY

Construction is underway at Paarl Rock, the fifth building in Concor’s 22-hectare Conradie Park development in Cape Town.

Piling for the eight-storey block began in May 2021, marking the start of a one-year building programme, according to Mark Schonrock, property development manager at Concor. Paarl Rock will comprise 266 architecturally designed apartments in an affordable model for first-time home owners. 

The block is underpinned by 158 continuous flight auger (CFA) piles, which present a quicker solution than bored or driven piles. With depths of 8 to 11 metres, the piles could be completed in just three weeks, Schonrock says, improving the pace of the project. 

“We have also installed two tower cranes – a 55 metre jib and a 45 metre jib – to facilitate our programme of work,” he says. These will lift and move concrete for vertical columns, as well as reinforcing bars for slabs and columns, and all formwork around the site.

Horizontal concrete slabs will all be post-tensioned, a current efficiency trend which reduces the amount of costly rebar required. The planned slab thickness has also been slightly reduced, from 285 mm to 255 mm. While a relatively small reduction, this will allow a saving of some 450 m3 of concrete over the planned area of 15,000 m2 of slab work.

“Pouring of slabs will be conducted by a truck-mounted boom placer, which enhances construction efficiency especially where large continuous pours of 200 to 220 m3 are required on this project,” he says.

The Paarl Rock block will include ground floor retail space, two lifts and a roof top deck on the sixth floor looking westwards at Devil’s Peak and over the Cape Town central business district towards Signal Hill. To minimise the cost of long-term maintenance on the outside walls, the design makes use of face brick – but with a difference. 

“Different colours and shapes of face brick have been specified to create texture and variety in the façade,” he explains. “Patterns are also created with rustication, using bricks of different shapes or with varied orientation.”

A perforated design is also used for the brick walls in front of drying yards, letting through light and air while also giving an attractive texture to the building façade. The laying of face bricks requires a somewhat elevated level of skill and attention, and also takes longer, so the best artisans are put onto the rustication work.

Schonrock notes that Cape Town still offers a good pool of bricklaying skills, but the long period of depressed conditions in the sector is going to be felt in skills supply as building activity improves. As part of its corporate contribution to skills development, Concor conducts a range of training on its Conradie Park site. 

“Through the National Youth Service programme, for instance, we are training six local bricklayer learners,” he says. “Beginning in November 2020, they completed a six-month training course and were then placed with selected sub-contractors to work on the current project.”

Paarl Rock’s innovations include an energy-efficient hot water system for residents, lowering their cost of living and taking load off the national grid. 

A centralised hot water generation system on the ground floor raises the upfront cost but provides many long-term benefits to users. An on-roof solar generator will assist in ‘over-heating’ water during the day in a specially-designed storage vessel to around 85 to 90 C. 

“Tapping into off-grid power in this way means that residents can save on what they pay in water-heating bills,” he says. 

The development is also conserving water and reducing water costs by supplying its own irrigation needs from a master incoming line of treated effluent – at just five to 10% of the cost of potable water. The water quality from this line, which is clean enough to be discharged into river systems, is further treated on site and also used for all irrigation and cleaning purposes.

Concor has been on site at Conradie Park – where the old Conradie government hospital closed about a decade ago – for about two and a half years, preparing the infrastructure for the developments. 

Roads have been installed, along with stormwater drains and a dedicated sewage reticulation system. A pump station was installed to move sewage over the Elsie’s River canal to the main Athlone sewer system and three new electrical substations were constructed.

The Conradie Better Living model is one of seven ‘game changer’ projects which has been prioritised by the Western Cape Government. This aims to improve the lives of citizens through the Finance Linked Individual Subsidy Programme, providing affordable housing situated near the city’s main arterial routes and job opportunities.