The surfaces of the horizontal construction joints were wet sandblasted, cleaned with air and water jets, and covered with a thin layer of mortar before starting concrete placement. To prevent the mortar from drying it was broomed just ahead of the fresh concrete. Figure 191 shows foundation preparation prior to placement of concrete in block 11. (b) Powerplant --The foundation rock and horizontal construction joints of the powerplant were prepared for placement of concrete by the same methods as those used for the dam. Figures 192 through 195 illustrate the preparation and procedure of placing concrete for a block placement. 172. Concrete Placement. (a) Dam.-- The mass concrete in the dam was placed as shown in figure 196. Each layer was placed across the block in line with the cableway and consolidated by vibration to within approximately 18 inches of the shoulder; the next layer was then placed against it and the concrete thoroughly consolidated on each side of the contact line. Succeeding layers were intergrated with those below by allowing the vibrators to pass through the layer being placed into the underlying layer. When each series of layers reached the top of the 7-1/2-foot lift the surface was vibrated with extra care to bury most of the coarse aggregate. To facilitate the removal of cleanup water, the top of each lift was placed 3 inches above the lift line grade at the downstream end and sloped uniformly to the upstream end, which was placed 3 inches below the lift line grade. Placing equipment consisted of 8-cubic-yard buckets carried by the cableway, oneman heavy-duty vibrators, and steel slip-forms. The 8-cubic-yard hydraulically operated buckets are worthy of special notation. These units contained a complete hydraulic system charged by the weight of the load. The bucket gates were actuated through a lanyard operated by the placing foreman which eliminated the necessity of attaching an air connection for gate operation. Figure 191. --View downstream in block 11 showing foundation prep- Figure 192. --Typical surface of construction joints between successive 7-1/2-foot lifts in the dam. Joint has been sandblasted and washed just prior to the placement of concrete on the surface. P591-421-3229, June 15, 1961. Figure 193. --Photograph taken from skip on cableway showing sandblasting and washing operations on block 17 in preparation for concrete placement. P591-421-3332, July 25, 1961. Figure 194. --First placement of concrete in Flaming Gorge Dam for the 1961 season. The concrete is being placed in block 14 at right of photograph. The photograph was taken looking across blocks 15, 14, 13, 12, 11 and 10 toward the left abutment. P591421-3059, March 23, 1961. Figure 195. --Workmen vibrating concrete into place in block 14. This is the first concrete placed for the 1961 season in Flaming Gorge Dam. P591-421-3061, March 23, 1961. |