Concor and Afrisam Partner in Concrete Mix Designs to Reduce CO2footprint in New Building

  • Concor is well on track to soon top out another elegant office block in the Oxford Parks precinct – with environmentally responsible readymix with a low CO2 footprint from AfriSam.

The modern 5 Parks Boulevard building is one of Intraprop’s latest projects in this fast-growing mixed-use development in Rosebank, Johannesburg. Such has been Concor’s success at Oxford Parks that the building is its seventh contract there.

“Like our previous Oxford Parks projects, this building is designed to achieve a high Green Star rating by the Green Buildings Council South Africa (GBCSA),” says Martin Muller, contract manager at Concor.

The office block will comprise four basement levels and five office levels, offering about 7,300 square metres of gross leasable area (GLA). The design includes a triple-volume atrium in the reception area to make the most of natural light and reduce energy. This feature extends from the ground floor through to the second floor. Further utilising the natural light is a double-volume area on the third and fourth floors.

“The structure is based on conventional reinforced concrete slabs from the basements to the roof, with a lift core to accommodate three lifts down to the lowest basement,” says Muller. “As the bulk concrete supplier, AfriSam is providing between 150 m3 and 250 m3 of readymix concrete for each slab.”

He highlights that, as a Green Star rated building, the concrete mix designs are required to reduce the overall CO2footprint of the structure. This has been achieved by using more fly ash in the mixes, thereby reducing cement levels by 30%. He notes that the quality and consistency of AfriSam’s mixes have allowed Concor to reduce the cycle time of each slab pour from the normal 11 days to nine or 10 days.

“On a fast track projects like this one, this enables us to speed up our cycle times as we can de-stress the slab and recycle formwork to the next level more quickly,” he says. “This will help us to top out the structure before the builders have their Christmas break this December.”

Quality assurance on the concrete is done both by AfriSam and Concor. After every concrete slab pour, concrete cubes are cast – then are crushed to test their strength after seven days, 14 days and 28 days. While 25 MPa strength concrete is used for the slabs, higher strengths from 35 MPa to 60 MPa are used for the columns and verticals.

The anchor tenant plans to occupy the third and fourth levels of 5 Parks Boulevard, and the schedule will see them take beneficial occupation in February 2023 to fit out the new building.

Author: Bryan Groenendaal

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