2003 – Use of the Sloped Layer Method for Bonded Joints on Tannur RCC Dam, Jordan

Tony Qiu and Brian A. Forbes

The RCC design review and construction supervision of the 60m high Tannur Dam in Jordan was carried out by GHD, Australia.

The 220,000m3 of RCC was placed during February-December 2000; change to the sloped layer method was made once the dam reached 15m height. It produced a 50% increase in placing rate and a considerable saving in costs.

The use of the method is the first known use outside of China, where it was developed during the construction of the 130m high Jiangya Dam in 1997-8. The sloping of the 300mm thick layers of RCC across the dam from bank to bank at grades between 5-8% ensures subsequent layers of RCC can be placed within the initial set time of the lower layer and hence the RCC is monolithic across the lift joint.

This paper briefly describes the project in Jordan and then gives specific details of the use of the sloped layer method. Typical results from the quality control testing during placement and subsequent coring and testing of the lift joints are also provided. The benefits of its use in adverse climatic conditions, such as extreme heat or rainfall and the ways it can be integrated with forming the upstream-downstream slope are also discussed.

The sloped layer method is a significant advancement, particularly for large structures, where lift joint cohesion, tensile resistance and RCC placing rates are vitally important.

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