Environmental Engineering Reference
In-Depth Information
Figure 15.17.
Joint layout and details for Reece Dam (Fitzpatrick et al., 1985, reproduced with permis-
sion of ASCE).
15.3.2.3
Vertical and horizontal joints
ICOLD (1989a) indicates that design practice at that time did not include horizontal
joints, except construction joints in which the reinforcing steel is carried through the joint
without waterstops. This is still current practice. Details of such joints are shown in
Figure 15.18
and
Figure 15.20
.
This was adopted because, when horizontal joints with
water stops were used, it was difficult to obtain good quality concrete around the water
stops and some joints experienced spalling under compression and mild rotation.
The Hydro-Electric Commission retained a horizontal contraction joint for Reece Dam,
to reduce thermal shrinkage and face cracking.
Vertical joints are generally provided at 12, 15, 16 or 18 m spacing depending on con-
struction factors. For smaller dams, narrower spacing is desirable, e.g. 6 m.
Most CFRDs have been constructed with each of the vertical joints being a construction
joint as shown in
Figure 15.15
and Figure 15.17. The joints are painted with asphalt, not
filled with a compressible filler, as these have been shown to compress under load and
cause opening of the perimetric joint. Cooke and Sherard (1987) advocated carrying the
horizontal reinforcement through all but a few joints near the abutments, in the manner
shown in Figure 15.15. This method gives a cost advantage and a reduction in potential
