A High RCC Dam with Low Grade Aggregates
The Koudiat Acerdoune RCC dam (H=120m, RCC volume = 1.55 million m3) is presently under construction in Algeria. Huge changes in the project were found to be necessary after commencing construction to adapt the dam to the geological foundation conditions and to the actual quality of aggregates. The paper describes the problems encountered when using RCC with weak alluvial marly shale aggregates. At Koudiat the RCC aggregates are natural alluvium, which comprises a mixture of shales, marls, limestone and sandstone. Some of the materials proved to be alterable under wet conditions after processing and when stockpiled. The RCC mix was designed to be as workable as possible in order to prevent any further alteration of the aggregates and creation of plastic fines when transported, spread and compacted. Additional fines to meet the RCC mix requirements were added to the mix, these were milled on site from limestone supplied from an existing quarry 60km from the site. Due to the unavoidable creation of some natural plastic fines during RCC production and placing, the desired workability of the mixed RCC was observed to decrease rapidly and to compensate for this and also achieve cement reductions, a set retarder and superplasticiser were introduced to the mix. The creation of natural fines when handling RCC, plus the rounded shape of the alluvial aggregate, made lift surface preparation difficult and time consuming. By implementing the Slope Layer Method, the contractor has been able to reduce these problems to some degrees. RCC placed to date (50％) is very consistent in quality. Several in-situ shear tests were made along lift joints, both in the full scale trial and in the dam itself, confirm friction angles above 45° being achieved in the dam. A lot of coring has been undertaken which shows that the compressive strength of the cores is 35％ less than the corresponding test samples manufactured in the site laboratory. This is considered to be due to several factors that are discussed inthe paper. The actual properties of the placed RCC to date fulfils the requirements of the design.
aggregate shale marls cores
Bernard Bouyge Brian A Forbes
Consulting Engineer. 28 rue Henri de Toulouse Lautrec, 31500 Toulouse, France Manager Major Dams Projects, GHD Pty Ltd, Brisbane, Australia
国际会议
第五届碾压混凝土坝国际研讨会(The Fifth International Symposium on Roller Compacted Concrete(RCC))
贵阳
英文
33-39
2007-11-02（万方平台首次上网日期，不代表论文的发表时间）