Amongst the key challenges of the project was the vertical concrete pumping height of 200 metres.To overcome this challenge and to avoid any blockages in a pipeline over 200 metres long, a super-plasticised concrete mix with a slump of 180 mm was used.
For the conventionally placed concrete and the concrete pumped to conventional pumping heights of between 30 to 50 metres, CHRYSO Southern Africa supplied AfriSam with approximately 65 000 litres of CHRYSO® Omega 140AFR, a hybrid plasticiser/super-plasticiser, specially formulated to perform optimally with concrete mix components used by AfriSam.
The addition of 19 000 litres of CHRYSO® Optima 100 super-plasticizer, allowed for concrete pumping pressures to be reduced to acceptable levels, at heights greater than conventional pumping heights; it also ensured a five-hour workability of the concrete mix, to allow for traffic delays when delivering to site.
The normal aggregate size of 22 mm for structural concrete was reduced to 13.5 mm and 9.5 mm as a further precaution to counteract friction stresses in the placing pipes and between the concrete-formwork interface. The result was a reduction in heat generation during placing and ensured that the aggregates had consistent paste coating from discharge to placing, with no segregation at this extreme placing height.
Client: Seventy Five on Maude (Pty) Ltd
Principal Agent: Legacy Development Management
Main Contractor: Aveng Grinaker–LTA
Specialist Sub-contractors: AfriSam SA (Pty) Ltd & CHRYSO SA (Pty) Ltd
The New coastal highway
This offshore viaduct is built 70 meters from the coast. It will stretch along the northwest coast of Reunion Island and will...
The Leonardo Entrance
The Leonardo rises majestically above the Sandton skyline, its iconic stature demanding to be noticed. What will also be...
This project consists of a 5 lanes, 760 meters long curved bridge over the Wouri river. 65 000 m³ of concrete are used....
The Cobalt area
This huge area, which is undergoing rehabilitation, hosts few companies including a start-up incubator. Most of the outdoor...
The tunnel that connects Asia and Europe, representing deposits of $ 1.25 billion. In this business, TBM Tunnel has the...
TThe bridge is part of the Izmir - Istanbul highway project. It is the 4th longest suspension bridge in the world. With this...
Colombo Outer Circular Highway
Construction of the Outer Circular Highway to the City of Colombo (from Kadawatha to Kaduwela) under the Ministry of Port and...
"World One" tower
Construction of the world's tallest residential skyscraper at over 450 meters. Superstructure comprising shear walls with...
East High Speed Train Line
First fully provincial high-speed rail link, the Rhin-Rhône LGV consists in an important stage in the development of the...
Soccer City Stadium, Johannesburg
Project Details: Soccer City (also known as the FNB Stadium) was earmarked to host both the opening and final matches of the...
Lesotho Highlands Water Project
Details of the project: Following the lessons learned from the devastating droughts of the late 1960's, a joint...