Construction World December 2017
Category A1: Civil Engineering Contractors
LOERIESFONTEINWIND FARM AND KHOBAB WIND FARM Loeriesfontein Wind Farm and Khobab Wind Farm, in the Hantam Municipality of the Northern Cape, are two pioneering renewable energy projects in which Concor Infrastructure played an important and innovative role.
(Also entered Category D)
the blinding beneath the bases. Concor Infrastructure used 50% waste material for both the 60 MPa plinth concrete as well as the 30 MPa conical base concrete. Strengths were achieved at 28 days. Together, these initiatives reduced the wind farm’s construction carbon footprint from approximately 300 kg of CO 2 per cubic metre to 90,7 kg of CO 2 per cubic metre, reducing the project’s estimated overall carbon footprint by 31%. Performance of concrete is vital for this demanding application. Each of the 122 wind turbine bases is 19 metres in diameter, and was constructed in the same manner to accommodate a 99 metre high turbine tower on which is placed a nacelle weighing in excess of 80 tonnes. To reduce the project’s carbon footprint, carefully selected and treated waste material was used as a replacement for cement in low cement geo-polymer readymix concrete. The bases at the Loeriesfontein site contained a design mix comprising 50% ground granulated corex slag (GGCS). For the blinding beneath the bases, as much as 95% waste replacement was used in the concrete. 50% waste material was used for both the 60 MPA plinth concrete and the 30 MPa conical base concrete with strengths being achieved at 28 days. The quality of the project’s core product – concrete – was proven and maintained throughout. In addition to the research and development invested in innovative and environmentally friendly concrete mixes, Concor Infrastructure’s testing is up to three to four times more thorough than conventional concrete inspections. They also exceed those undertaken on concrete performance on wind construction projects, and involve studying the micro- crystal formations of the concrete using Environmental Scanning Electronic Microscopes (ESEM) .
The wind farms were constructed by Concor Infrastructure in a consortium with CONCO. Concor Infrastructure was responsible for the construction of all 122 wind turbine generator foundations, as well as the adjoining hard stands and all internal roads on both sites. The company brought its extensive these construction projects in a remote endemically sensitive and arid location. In planning and implementing its work, Concor Infrastructure was able to ensure a high quality product and service – with innovative cement-saving concrete mixes for the wind turbine bases – as well as water saving strategies and environmental care, all delivered well ahead of schedule. The environmental impact of the project was carefully considered and addressed through a number of integrated strategies. These included the conservation and recycling of scarce water resources, the bioremediation of hydrocarbons on site, relocation of protected plant species and an overall reduction in the project’s carbon footprint. Concor Infrastructure was also able to promote local employment and skills development in the area by sourcing experience and expertise in civil engineering, concrete design and sustainable project management to
much of its labour from the town of Loeriesfontein. In addition to the training provided, Concor Infrastructure mentored local small businesses to become effective suppliers and subcontractors. The company’s ongoing commitment to Zero Harm through strong health and safety practices allowed the projects to reach the 1,3 million LTIF (Lost Time Incident Free) milestone in January 2017. As at August 2017, the project was standing on 2 million LTIF for the Consortium. The wind farms are both part of the South African Government’s Round 3 Renewable Energy Independent Power Producer Procurement Programme (REIPPP). South Africa Mainstream Renewable Power has managed the construction and will manage operations of these wind farms, following commercial operations. Substantial innovation in concrete mixes was applied at the Loeriesfontein and Khobab sites, contributing to various environmental considerations while enhancing performance. The plinths at Loeriesfontein were constructed using high strength 60 MPa concrete with a design mix comprising 75% ground granulated corex slag (GGCS) in place of cement. As much as 95% waste replacement was used in the 12 200 cubic metres of 15 MPa concrete used for
• Company entering: Concor Infrastructure • Client: South Africa Mainstream Renewable Power • Start date: 7 April 2015 • End date: 7 December 2017 • Project team: Concor Infrastructure • Principal agent: Mainstream Renewable Power • Project manager: Mainstream Renewable Power
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