Construction World December 2023

stockpiled safely whereby it would be cleaned and re- utilised at a later stage. Rock was encountered in most areas within the boundary of the site and specialised drilling and chemical blasting took place to remove approximately 500 m 3 of granite. The bases were then bunded with earth and covered with plastic to prevent water permeating on to rock face. Once the rock had successfully fractured, the 8-ton excavators were brought back in to remove the layers of rock and break down the rock in o a size that could be safely carted away. Due to the size of the bases, all bases were pumped utilising a specialised 40 Mpa mix of concrete developed by AfriSam for the foundations. As the works taking place at ground level were considered to be the highest risk in terms of affect on

the lateral support wall, a detailed daily inspection was executed at specific points at the base of the lateral support walls as well as at the top of the lateral support walls to monitor any and all movement. A number of detailed construction methods were designed and planned upfront to ensure the requirements of the superstructure were met. This included the fabrication of specialised sleeves and plates that were to be installed in the double volume columns on all floors. These sleeves had to be installed as a method of future proofing the columns to accommodate intermediate concrete slabs at a later stage should the client wish to increase the number of basement levels. The columns on the project required the development of an ultra-high strength concrete to meet the needs of the design team as well as the contractors on site in terms of placing. This concrete needed to achieve a crushing strength of 80 Mpa. Special care had to be taken to cure the slab with differing strengths as the 80 Mpa mix cured differently to the 30 Mpa concrete. This resulted in several methods being utilised at one time to cure the slab, including curing compounds, water and covering the slab in plastic in isolated regions. Stella P1 was a Greenstar project and required Environmental Authorisation to be obtained. As such, there was a detailed Environmental Management Plan (EMP) drafted for the development and the requirements therein were strictly adhered to mitigate any adverse environmental impacts. 

PROJECT INFORMATION

• Company entering: WBHO Tiber Joint Venture • Client: Fortress • Main Contractor: WBHO Tiber Joint Venture

• Architect: LYT Architects • Principal Agent: Profica • Project Manager: Profica • Quantity Surveyor: MLC • Consulting Engineer: WSP

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22 nd Best Projects Awards 2023