ICOLD Bulletin: The Physical Properties of Hardened Conventional Concrete in Dams
Section 2 (Strength properties)
As submitted for ICOLD review, march 2008 Section 2-26
Tab. 2.9 – Use of blended cements in selective dams
Blended cements need more testing (a) because of the properties of pozzolans may
vary widely and (b) because the quantity of blended materials has to be optimized with
respect to strength and durability. Fig. 2.10 [2.42] shows an example of a test series
resulting in the choice of 30% fly ash for this particular dam concrete.
Furthermore using blended cements reduces the heat of hydration.
2.3.6 Effect of sustained loading
In a standard test, the compressive strength is determined at loading in the range of
minutes. As this range of minute increases, lower strengths are recorded than in the
case of standard test. If, on the other hand, the load is applied more rapidly, a higher
strength is recorded. The well-known Rüsch-diagram in Fig. 2.11 demonstrates this
phenomenon impressively [2.43].
Under the low rates of loading, creep occurs. It flattens the stress-strain curve, however
only at a degree of loading, which does not exceed 70 to 80 % of the short-term
strength. The process of cracking during loading explains this behaviour. The
breakdown of concrete consists in the formation of cracks, either their extension with
arrest (stable cracking at low stress levels), or their extension without arrest (unstable
crack propagation at high stress levels).
kg/m3 %
ZillergrŸndl/Austria arch 1'400 170 fly ash 33
Katse/Lesotho arch 180 fly ash 30 to 50
Luminei/Italy arch 100 270 pozzolans 25
Cancano II/Italy gravity 520 240 pozzolans 37
Vajont/Italy arch 265 250 pozzolans 35
Tagokura/Japan gravity 1'950 140 fly ash 25
Hitotsuse/Japan arch 560 215 fly ash 30
Itaipu/Brazil buttress 12'000 130 fly ash 23
Francisco Morazan/Honduras arch 1'510 150-180 pozzolans 25
Hungry Horse/USA arch-gravity 2'350 165 fly ash 55
Monticello/USA arch-gravity 248 170 calcinated diatom. clay 25
Yellowtail/USA arch-gravity 1'340 177 fly ash 28
Longyangxia/China gravity 1'587 160 fly ash 30
Ankang/China gravity 3'250 130-155 fly ash 30 to 55
Ertan/China arch-gravity 4'100 174 fly ash 30
Puylaurent/France arch 85 250 fly ash 40
Pieve di Cadore/Italy arch-gravity 377 200 pozzolans 25
Valle di Lei/Switzerland arch 862 230 pozzolans 35 to 37
Baserca/Spain arch 238 200 fly ash 25
Llauset/Spain arch 211 200 fly ash 25
Las Portas/Spain arch 641 200 fly ash 22.5 to 30
Alcantara/Spain buttress 950 250 pozzolans 30
Cedillo/Spain gravity 800 225 pozzolans 30
Content of cementitious
material for interior
concrete
Dam/Country Type of blended material BlendingType of dam
Concrete
volume