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ConFrex 2012 Seminar

Concrete for Fluid Retaining and -Excluding Structures

More than 300 delegates attended the recent seminar road show organised by the Concrete Society of Southern Africa NPC in association with the Cement and Concrete Institute. ConFrex 2012 focused on concrete for fluid retaining and –excluding structures and attracted consulting engineers, contractors, suppliers and academia from many sectors of the built environment.

In his introduction message, John Sheath, CEO of the Society and Chair for the seminar proceedings, referred to the State President’s Infrastructure Plan and its integrated projects requiring more investment in water infrastructure. A total ofR570 billion investment is required in the next decade by the entire sector across the total value chain, from source to tap and waste to source.

To set the scene for the seminar, the key note address was presented by representatives of the Department of Water Affairs. Ockie van den Berg, Chief Engineer: Options Analysis North and Jaap Kroon, Chief Engineer,External Works. Their presentation provided delegates with an insight into the Department’s strategy and plans for water retention and supply over the next few decades. Focus was centred on:

- Strategic water resource planning

- Asset management

- New infrastructure investment

After describing the above in some detail, the speakers assured the audience that there were great opportunities for consultants and contractors to address the challenges in the water sector!

There was great interest in the two case studies that were presented, firstly by Rob Fraser and David Stables, Berg River Consultants on the Berg Water Project in Franschhoek, Western Cape, and then by Jaco van NieKerk, DWA Directorate: Construction West - De Hoop Dam Project. This was a fascinating look at concrete in action at these two prestigious dam sites. Of particular interest was the innovative use of immersion-vibrated roller-compacted concrete (IV-RCC) on the De Hoop Dam which is being built on the Steelpoort River on the border of the Mpumalanga and Limpopo Provinces. This technology has enabled the contractor to place concrete at great speed, breaking previous records  by a large margin.

On the more technical side, delegates heard details presented on the new proposed South African design standard for concrete for water-retaining structures. This was presented by Dr. Celeste Barnado-Viljoen of Stellenbosch University who explained that this new standard was necessary in the long term as the currently used British Standard BS8007 has been officially withdrawn.  The UK now uses EN 1992-3 for the design of water retaining structures. This implies, she stated, that the BS8007 will no longer be maintained by the UK in terms of revisions to keep up with new technology and knowledge on material behaviour.  In the short term this is not a crisis for SA, but in a decade or so it will become an issue as better technology and materials emerge.

Dr. Barnado-Viljoen described the work that had been done to date by a colleague at the University and concluded by appealing to delegates to volunteer to join a Working Group to resolve issues including the basis of design issues, materials, detailing, construction methods, SANS 10100 revision and non-technical issues.

This paper was followed by a presentation on the new SANS 50450 specification covering fly ash for concrete. Lehlohonolo Madumo, Technical Manager from Ash Resources (Pty) Ltd., provided a comprehensive overview of this new specification, covering not only the its full requirements and their implication for both manufacturer and user, but also a case study in Bahrain where he was able to demonstrate how the use of a classified fly ash to the new specification can produce a high strength, dense concrete with the minimum of heat of hydration.

Waterproofing of concrete was next on the programme and delegates heard from Lewis Lynch of Xypex Africa and Kobus Botma of Stoncor Africa details of the available options to clients for waterproofing concrete and the latest developments in the various types. Everything from active crystallisation technology to pre- and post-applied membranes was covered and delegates gained a good insight into the mystical world of waterproofing.

The final presentation of the seminar featured Gary Theodosiou from the Cement and Concrete Institute, who described the challenges that face engineers with regard to design and concrete materials for liquid–retaining structures.  He emphasised that the construction of successful concrete liquid-retaining structures have special requirements for durability, water tightness, control of cracking and joints, and that common defects are generally associated with porous concrete, uncontrolled cracking, defective joints and continuous leakage paths. He presented a case-study highlighting the various factors that could contribute to the vertical cracking of a reservoir.

In closing the seminar, the Chairman thanked all the speakers for their time and support of the event; the many sponsors who had contributed generously; the Organising Committee comprising, Nick van den Berg, Immediate Vice-President of the Society, Hanlie Turner, Marketing Manager of the C&CI and Natasja Pols and Jeanine Steenkamp from CSSA Head Office.

He reminded delegates of the forthcoming seminar in October – ‘ConCrax 2012’ focusing on the cracking of concrete and for their attendance at ConFrex without which there would not have been an event.

celeste david delegates ockie

Dr. Celeste Barnardo-Viljoen
Stellenbosch University    

David Stables
Berg River Consultants 

Delegates at the Inland Seminar
at Emperor’s Palace

Ockie van den Berg
Deptartment of Water Affairs


jaco group

Jaco van Niekerk
Department of Water Affairs

Lewis Lynch, Jaco van Niekerk,
Jeanine Steenkamp, John Sheath

Lots of interest shown at the
company display stands

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