THE ROLLER-COMPACTED CONCRETE GRAVITY DAM 179
crack inducers vibrated into the RCC. The ‘joints’ were subsequently
sealed by a 600 mm wide external waterstop bonded to the face. Seepage
through the dam body diminished to a satisfactory 10–12 l/s over the first
12 months’ operational service.
The first use of RCC in Turkey, for the 124 m high by 290 m long
Cine gravity dam (originally planned as a rockfill embankment with a clay
core) is presented in Ozdogan (1999). The low-paste RCC used for Cine
has a cement content of 70 kg/m^3 , with 90 kg/m^3 of PFA and 88 l/m^3 of
water. Target 180 day compressive strength was specified as 24 MN/m^2.
The concept of the RCC dam has attained maturity, most of the
initial concerns with regard to the performance of the earliest RCC dams
such as the higher permeability leading to greater seepage flows and
reduced durability, and the issue of providing a durable and aesthetically
satisfactory facing, having now been successfully addressed. RCC mix
selection and design is now a well-understood sector of concrete techno-
logy. Gravity and even arch dam profiles have been rationalized for rapid
and economic construction in RCC. Recent developments in RCC dam
practice have therefore centred upon refining the overall construction
process, optimizing concrete production and placing operations to raise
output and enhance consistency of the product at a reduced gross finished
unit cost/m^3 for the RCC.
Reviews of contemporary RCC dam technology and practice,
together with descriptions of completed projects and others as yet in the
planning stage, are presented in Berga et al. (2003) and ICOLD (2004).
Understanding of the RCC mix is discussed in Schrader (2005), and the
same author considers the construction of RCC dams in relation to more
difficult foundation conditions in a later paper (Schrader, 2006).
Construction of the Miel 1 dam, Colombia, the tallest RCC dam in
the world at the time of it’s completion in 2002, is described in Santana
and Castell (2004). The body of the dam was divided into zones according
to design stress level, with four different RCC mixes employed with
cement contents ranging from 85 to 150 kg/m^3. The incidence of cracking
due to thermal stress was controlled by cutting transverse joints in the
freshly placed RCC at intervals of 18.5 m, a similar longitudinal joint being
cut in the lower levels of the dam. Average RCC mix parameters for Miel
1 are quoted as being:
compacted density : 24.7 kN/m^3
Poisson ratio: 0.23
angle of shearing resistance: 45 deg
strain capacity: 80 microstrain
thermal diffusivity: 0.00335 m^2 /h
thermal expansion: 7 10 6 m/deg C.