Hydrotechnical concrete of the Ust-Ilim hydroelectric station

Abstract

1. A decrease of cement contents compared to analogous compositions of the Bratsk hydrostation, improvement of concrete quality, and increase of general technological discipline attest to definite progress in the technology of hydrotechnical concrete at the Ust-Ilim hydrostation. Further progress is associated with the selection of a rational technology on the basis of the experience of the Bratsk and Ust-Ilim hydrostations, modernization of individual components, and creation of a system of automatic compensation of the variability of the moisture content of aggregates at concrete plants, mechanization of concreting operations in the blocks, and increase of general efficiency. 2. Site tests of the concrete of the Ust-Ilim dam and the results of observations of seepage through the concrete of the upstream face showed that the solid concrete mass is practically impermeable and the relatively small seepage flow occurs along cracks and horizontal joints. One of the directions of the rational use of concrete can be a further reduction of the cement contents in concrete of the upstream column to an extent which does not cause damage when used as a material and will promote an increase of crack resistance of individual blocks and structures as a whole. 3. An analysis of the results of testing control samples and visual observations of the state of concrete surfaces showed that when assigning the concrete composition it is absolutely necessary to take into account the conditions of hardening of the concrete in the structure. In massive and underwater structures concretes with low cement contents harden most intensely and for the longest time. The strength reserves occurring in this case remain, as a rule, unused. In outer surface zones, conversely, early drying and other unfavorable factors can lead to a decrease of the potential possibilities of concrete. 4. The prescribed technical parameters of the concrete of the spillway surface and variable-level zone were completely provided as a result of introducing a number of measures: blending of special compositions, development of technology of placement, etc. The wider use of rubble in especially important concretes is characteristic for the Ust-Ilim hydrostation as a whole.