CEMENT & CONCRETE
An 8 m high and 500 mm thick concrete shaft, emerges into a cone-shaped reservoir with a floor up to 1.2 metres thick and a final diameter exceeding 26 metres.
“ The base mix comprised 70 % ground granulated blastfurnace slag( GGBS) and 30 % AfriSam High Strength Cement, reducing the ordinary Portland cement( OPC) content to just 20 %,” says Ndlovu.“ Despite the low OPC content, the mix exceeded expectations – achieving the target strength of 51 MPa in only 28 days in relation to the designed 56-day requirement.”
The construction process placed high demands on the readymix in terms of both slump control and delivery accuracy. With over 210 kg of rebar per cubic metre in some sections, AfriSam developed a highslump pump mix for vertical pours, while limiting the slump to 130 mm in inclined sections to prevent concrete from sliding off the shuttering.
Sheldon Temlett, Contracts Manager at M & D Construction, emphasises the significance of this mix’ s performance.“ With such dense steel and complex geometry, AfriSam’ s mix gave us the workability we needed without compromising quality. Their team worked closely with us to adjust slump levels and plan deliveries around our 12 m ³/ hour pour rate.”
AfriSam Territory Manager Toni Williams mentions that logistics were precisely coordinated with construction progress to prevent delays or idle time on site.“ Coordination was key to supporting M & D’ s controlled rise rate of 1 metre per hour, especially as the concrete had to set before each formwork had to partially could proceed.”
Installing the reinforcing steel was key, with more than 210kg of rebar required per cubic metre.
Construction of the Main Reef water tower started in September 2024 and is planned to be completed by April 2026. Once operational, it will deliver vital water infrastructure to about 20 000 homes in the Goudrand housing development – a major project led by the Gauteng Department of Housing, the City of Johannesburg, and Blue Print Housing. # CreatingConcretePossibilities.
40 summer 2025-26 | www. tobuild. co. za