Author: Edwin Lillie, Elvin Pesch, Louis Barnard
Conference: SANCOLD Annual Conference and AGM 2018
Date: November 7-9, 2018

ABSTRACT
The construction of Neckartal Dam started in September 2013. The full-scale trial section was done in August 2015 and the first RCC was placed on the dam foundation in October 2015. The RCC placement was completed 32 months later in May 2018. This paper gives a brief history of the RCC through the various project phases. Two mixes were used, a 20/38 high cementitious mix for an impermeable zone (Zone 1) in the upstream face of the dam and two 10/38 low cementitious mixes for the main body of the dam (Zone 2). The Contractor produced a total of 3.12 million tons of aggregate for the project over 33 months at an average of 94 800 tons per month. The overall crushing plant efficiency over the 33 months of production was 33%. The Contractor produced a total of 836 000m³ of RCC for the project over 32 months at an average rate of 26 127m³ per month. The overall plant efficiency over the 32 months was 17%. Over the whole RCC placement period, there were interruptions for many reasons, some within the Contractor’s control such as plant breakdowns, insufficient sand, cement and/or fly ash, waiting for shutters to be moved, preparing RCC surfaces, sequencing of the intake tower construction etc. There were also some delays beyond the Contractor’s control such as strikes, break downs and late payments. The RCC cube tests indicated that the set RCC easily achieved the strength requirements of the project specification of 20MPa at 365 days for Zone 1 and 10MPa at 365 days for Zone 2.

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