Inland Branch - Technical Seminar: Roller-Compacted Concrete in Dam Construction
The use of roller-compacted concrete has taken an upward trend in recent years, with new dam construction utilizing this innovative method of placing concrete in the dam walls.
In this latest seminar organised by the Inland Branch of the Concrete Society, delegates were given a detailed overview of the latest designs and practice in RCC concrete.
The scene was set by Jan Brink from Royal HaskoningDHV consulting engineers with a presentation that firstly explained the reason why water storage and conservation were so important to the country, followed by a description of the different types of dam that can be constructed. These included earthfill, rockfill, concrete-faced rockfill, arch, mass concrete and of course, RCC.
The next speaker, Nithia Pillay from AfriSam presented details of the roller-compacted concrete used in the construction of the Spring Grove Dam in KwaZulu-Natal. Spring Grove Dam will augment the Mgeni system by 60 million m3 to supply water to about five million downstream users in the Durban and Pietermaritzburg areas. The optimised wet paste roller-compacted concrete mix developed on this project was a first in South African dam building and can be used for future dams. The heat of hydration was kept within limits resulting in a dam without any cracking due to hydration related temperature increases.
George Evans from PPC provided delegates with an oversight of the construction of the De Hoop Dam in Limpopo. This award-winning structure, with a dam wall height of 88 metres utilized 1,1 million m3 of roller-compacted concrete. It was commissioned early in 2015.
The expectations of the RCC were to achieve the specified properties and meet the handling requirements by placing one RCC Mix from Shutter to Shutter by means of Conveyor System; and ADT Trucks.
A further expectation was the ability to vibrate against the formwork by means of Immersion Vibration; and to vibrate the central section by means of roller compaction. International expertise was utilized in the development of the final concrete mix and the result, Immersion Vibrated Roller Compacted concrete was a truly ground-breaking achievement.
The final speaker was the Inland Branch Chairman, Roelof Jacobs from Lafarge who began by outlining the progress that has been made over recent years in developing sophisticated concrete mixes that challenge the boundaries of both cement and concrete technologies.
With the worldwide trend of reducing carbon emissions and conserving natural resources, international and local cement manufacturers have switched to more environmentally friendly cements within the wide scope of the international cement specification EN 197-1:2013.
Some of these cements, which also contribute towards enhanced durability, lower heat development, improved workability and resistance to aggressive environments are suitable for RCC dam construction.
Roelof concluded by describing the design, mixing and placing of the roller-compacted concrete used in the construction of the Metolong Dam, an 83 metre high RCC dam with a design crest length of 280 metres, approximately 35 km from Lesotho’s capital, Maseru. He demonstrated the integrated solutions provider approach to major projects, and how the cement supplier had contributed technical, commercial and logistically innovative solutions to help the construction of the Dam.
Nearly 70 delegates attended this seminar and the Inland Branch is very grateful to event sponsor AfriSam for their generous support and those companies that displayed their products and services at the seminar –
- The Concrete Institute
- Mapei SA
- Sephaku Cement
- Ash Resources
- BASF – Master Builders
- Doka Formwork
RCC Seminar - Photo Gallery
(Click on images to enlarge)