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208. Temperature Observations. Thermometer wells consisting of 1-inch-outsidediameter cooling pipe tubing were installed in the centers of concrete lifts in each block at 30-foot elevation intervals. The pipes extended from near the block centers to the downstream face of the dam. Access to the pipes was by ladders between catwalks from which the cooling headers were maintained. Insert-type resistance thermometers were inserted into the embedded pipe to obtain concrete temperatures. The electrical resistance of these thermometers was measured with one of two types of modified wheatstone bridge test sets. Two different test sets and two differently calibrated types of thermometers were used to obtain temperatures. Because of the arithmetic involved, depending on which test set and which type of thermometer were being used, careful identification was required by personnel taking readings to insure against errors in recording temperatures. At various times during the cooling program, erratic temperatures were recorded, and some of these readings were probably due to operator error in converting resistance readings to temperatures.

Monthly reports were submitted to the Denver office on the progress of concrete cooling. The monthly report included such factors as: status of initial and secondary (final) cooling, plotted or tabulated concrete temperatures, cooling water temperatures, river water temperatures, maximum and minimum daily air temperatures, concrete placing progress, aggregate sprinkling operation, contraction joint grouting summary, cracking of mass concrete in the dam, and general observations on cooling operations.

H. Contraction Joint Grouting

209. Introduction. Contraction joint grouting of the dam was performed during the winter and early spring in 1962 and 1963 after final cooling of the mass concrete was completed for each of those 2 years. The first group of contraction joints was grouted January 18, 1962, and the last group was completed on April 18, 1963. Five joints or partial joints including three on the right abutment and two on the left abutment were not grouted.

210. Grouting Systems. In general, the contraction joint grouting systems were similar to standard designs used on other Bureau dams. A separate grout system was installed between vertical seals at the upstream face. The two completely separate grout systems at each joint were installed to provide the maximum opportunity for the joints to be effectively sealed.

A modification of the grout header arrangement as shown on figure 24 was made in the field. The 1-1/2-inch vent and vent return headers from the upstream system and the vent return from the main system were brought up past the horizontal grout seal, and were taken to the downstream face with the supply and return headers of the next grout lift. This method simplified pipe fitting and concrete placing, since all the headers could be brought out in one lift. The headers were kept close to the bottom of the lift rather than being hung from the top of the forms, and it was easier to protect them during placing operations.

The Z-type metal seals used in the contraction joints were fabricated from a No. 20 gage corrosion-resistant steel. Permission was given to the contractor to use copper for the horizontal seals near the foundation rock, but copper seals were used only during the first placing season. Some difficulty was experienced by the contractor in effectively welding the metal seals. Best results were obtained with the welding machine set at a low amperage and using a low-heat welding rod. The metal used in the seals was quite tough and inflexible. Considerable difficulty was experienced by the contractor when bending the seals to extend from the formed high block joints into the low blocks. Inexperienced workmen sometimes damaged the seals by pounding or hammering to bend them.

211. Grouting Procedures. Contraction joint grouting was generally performed immediately following the completion of final cooling in a 60-foot grout lift. The joints were grouted in groups of three to six; the usual hookup consisted of four joints including both the upstream and main or downstream sections of the joints. On the day before a group of joints was to be grouted, the joints were washed and pressure tested with air and water.

Selby Drilling Corp., who was the subcontractor for all drilling and grouting operations at Flaming Gorge Dam, performed the contraction joint grouting. A crew of from four to six men and a foreman was required for the joint grouting. The plant used for most of the contraction joint grouting was housed in a semitrailer van located in the powerplant parking

area. A crow-type grout mixer, a grout agitator, and small grout pump were installed inside the van, and a large duplex-type pump outside the van supplemented the smaller pump when higher pressures were required. This plant and similar plants located on the left abutment in the spillway intake area and in the right abutment parking area were used for all the contraction joint grouting and foundation grouting operations. One and one-halfinch high-pressure "bull" hose was used for almost all the grout lines and header connec

tions.

212. Grouting Methods. The contraction joints were grouted in 29 hookups. These hookups were determined in relation to construction and cooling progress and for convenience in grouting. The concrete cooling requirements are discussed in sections 200 and 201. In general, a minimum of 60 feet of concrete, or the next higher grout lift was required above the lift being grouted so that a waterload in the upper lift could be applied to the joints being grouted. In order to complete the contraction joint grouting in 1962 to elevation 5760, above the river outlet tubes (elevation 5743), this requirement was modified to allow grouting of that one lift with a minimum coverage of 7-1/2 feet of concrete in the low blocks. In addition to the next higher lift, water curtains were also applied to two adjacent joints at the same elevation when these joints had not yet been grouted.

Grout mixtures with water-cement ratios ranging from 2:1 to 0.75:1 were used in grouting the joints. Joints which were relatively tight when water tested, were usually started with a few sacks of 2:1 water-cement grout and then finished with either a 1:1 or 0.75:1 water-cement grout mixture. Wherever possible the thicker mixes were used. In general, grout was supplied to the joints uniformly over about a 4-hour period and they were filled at equal rates. Considerable difficulty was experienced in filling the upstream grout systems and in obtaining grout returns and pressure at the vents. One method used in filling the upstream sections was to completely fill those systems with 2:1 water-cement grout at the start of the grouting operations and then as the main systems were filled and maximum joint openings were obtained, to apply thicker grout to the upstream systems and bleed off the thinner grout at the vents. Some of the upstream sections in the higher lifts, particularly the top (elevation 6000-6047) grout lift, would not vent even when tested with air and water. Most of these systems were satisfactorily grouted with a 2:1 water-cement grout after the downstream sections of the joints were filled and vent pressures of from 60 to 80 pounds per square inch were obtained at the downstream vents. This procedure apparently opened up the joints enough to allow them to be grouted, but did not result in excessive deflection of the joints.

The vent lines of both the upstream and downstream systems were provided with valved riser pipes. The valves were left open until thick grout returned from the vent risers, and were then closed and pressure was applied to the supply headers. Pressures ranged from 0 to 80 pounds per square inch, but usually averaged about 50 pounds per square inch. When grout leaks occurred, the applied pressures were kept low, sometimes with the 5-foot static head of grout in the vent riser as the only pressure on the joint. The higher pressures were used to open up tight joints as outlined above. Joint deflections during grouting operations were measured with dial gages, registering to 0.0001 inch, which were mounted across the contraction joints at the top of the lift being grouted.

The final construction report1/ contains a detailed summary of contraction joint grouting, and a briefer summary is included in this technical record as table 2. In all contraction joint grouting through 1962 (up to elevation 5760), a total of 220, 210 square feet of joint area was grouted, and a total of 2, 898 sacks of cement retained in the joints for an average of 76 square feet of joint grouted per sack of cement. The total quantities for the 1963 contraction grouting season (elevation 5760-6047) were 305, 220 square feet of joint area grouted and 3, 105 sacks of cement retained in the joints for an average of 98 square feet of joint grouted per sack of cement.

The total quantities for the dam were 525, 430 square feet of joint area grouted and 6,003 sacks retained in the joints for an overall average of 88 square feet of joint grouted per sack of cement.

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213. Grout Leakage. Grout leaks during contraction joint grouting operations were encountered at various locations including: formed drains; through vertical grout seals at both the upstream and downstream face; into the shale seams and foundation rock; at contraction joints and cracks in the galleries; between upstream and downstream sections in the same joint; in vertical cracks on the downstream face 1 or 2 feet from the joint; past horizontal seals into the lift above; and at the horizontal cantilever joint. Most of the leaks were calked or stopped during grouting operations with little difficulty.

Leaks into the formed drains were controlled by plugging the drains at the bottom and letting them fill with grout. Short sections of the inflatable pneumatic tubes used to form the drains were used as plugs. The drains were allowed to fill to a level higher than the joint being grouted and were then left full for several hours until grout in the joint became less fluid. The drains were then drained and flushed of all grout. No formed drains were lost by this method, and these joints were satisfactorily grouted.

Leaks past vertical seals on the downstream face and leaks in galleries around seals and in hairline cracks were calked easily with lead wool or by peening. In most cases joints with leaks such as these were grouted satisfactorily after calking. For one or two joints, it was necessary to regrout the downstream section from the vents after calking leaks past the seal on the downstream face. Several joints developed vertical cracks extending from the vertical grout seal to the downstream face about a foot from and parallel to the contraction joint. In general this type of leak was satisfactorily controlled by calking with lead wool and reducing final pressures at the vents. There was very little leakage in or near vertical joints on the upstream face.

In general, when the upstream and downstream sections of the same joint leaked together, the joint was filled from both headers simultaneously and adequate pressures were obtained at both vents. Very few of the joints leaked into the lift above, and most of these leaks were very minor. One exception was the 3-4 joint which leaked heavily

into the elevation 6022. 5-6047 lift while the elevation 6000-6022.5 lift was being grouted. This joint was finished with a vent pressure of 10 pounds per square inch and the lift above was thoroughly flushed.

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Several abutment block joints leaked into the foundation rock and shale seams. the 18-19 and 19-20 joints from elevation 5700 to elevation 5760 took excessive quantities of grout and had to be regrouted. The 18-19 joint leaked in the rock-concrete contact at the toe of the dam and from the foundation rock about 15 feet downstream from the dam. The 19-20 joint took grout excessively but no visible leaks were observed and it is assumed that it was leaking past the horizontal seal into the foundation rock. Both joints were subsequently satisfactorily regrouted from the vents.

While grouting the elevation 6000-6047 lift, several joints leaked heavily from a horizontal joint or crack where the roadway cantilever extends from the downstream face of the dam. Since these leaks were at very nearly the same elevation as the top horizontal metal grout seal, and since they were inaccessible for calking, these joints were filled until heavy grout ran from the horizontal cracks and were then considered completed.

214. Cement for Contraction Joint Grouting. The specifications provided for a special air-separated, type II low-alkali cement to be furnished in waterproof bags with 100 percent of the finished product passing a No. 100 United States standard screen, and 98 percent passing a No. 200 United States standard screen.

Initial samples of cement furnished by the manufacturer to the contractor failed to meet the requirement of 100 percent passing a No. 100 screen. This cement did meet the required 98 percent passing a No. 200 screen, and permission was obtained from the Denver office to use 200 barrels of this cement until cement meeting the specifications could be obtained. No difficulties were experienced in pumping 1:1 and 0.75:1 water-cement ratio grout made from this cement through the relatively small joint openings near the bottom of the dam.

The same manufacturer later supplied cement which did meet specification requirements. Grout mixtures from the special cement were thicker than equivalent watercement ratio mixes using regular type II sacked cement which had not been specially processed to meet fineness requirements. The thicker 0.75:1 and 1:1 water-cement ratio mixes from the special cement invariably plugged the grout headers or the contraction joints before grouting was completed, and it became necessary to use a 1.5:1 watercement ratio mix for most of the joints between elevations 5640 and 5760.

Permission was received from the Denver office to use regular sacked cement during the 1963 contraction joint grouting operations. About equal amounts of special and regular sacked cement were subsequently used. Although there was not nearly as great a difference in mixes from the two cements as was observed the previous year, it was generally easier to pump grout mixes made with the regular sacked cement.

Some difficulty with slow set was experienced in March 1963. Valves on some grout headers could not be removed for over 24 hours after grouting of the headers had been completed. This problem did not recur.

215. Cooling Coil Grouting. The concrete cooling coils in the dam were backfill grouted with a heavy (0.75:1 to 1:1 water-cement) grout upon completion of concrete cooling and contraction joint grouting. The coils were usually grouted in 60-foot lifts after all the joints in a lift were completed.

216. Diversion Tunnel. In January 1963 the contraction or periphery joint between the concrete tunnel plug and the concrete lining of the diversion tunnel was grouted using a total of 85 sacks of cement. During the same period, the tunnel plug cooling coils and the 18-inch-diameter diversion pipe were backfilled. A total of 51 sacks of cement grout were placed in the diversion pipe, and 7 sacks were retained in the cooling coils.

I. Powerplant Roof Slabs, Insulation, and Roofing

217. Roof Slabs. The slabs were precast and installed on the powerplant and service bay roofs in March and April of 1962. They were furnished and installed under a subcontract by Otto Buenner and Co. of Murray, Utah. A coarse and medium expanded shale

was approved as aggregate for the slabs. No significant difficulties occurred during installation. A few cracked slabs that arrived on the jobsite were rejected and replaced.

Insulation and Roofing. The insulation, vapor seals, membrane waterproofing, and other appurtenant materials in the construction of the roofs of the powerplant, offices, outlet structure, and elevator tower were furnished and installed under a subcontract by the Gresham Roofing Co. of Ogden, Utah.

The placing of the insulation and 5-ply membrane waterproofing commenced on the control bay roof on March 28, 1962, and the roof was completed with cover slab in April 1962. The subcontractor commenced laying the lower vapor barrier on the powerplant roof on April 13, 1962, and completed the roof, including the gravel coating on May 16. He commenced placing the membrane waterproofing on the transformer deck roof on July 7, and completed it on July 21, 1962. The built-up roofing on the roofs of the outlet gate structure, the office, lobby, tool, and welding rooms and the elevator tower was laid in August of 1963.

A 3-inch-thick structural insulation board, a vapor barrier, and 5-ply asphalt membrane were applied on the control bay roof according to the specification requirements. After installation, numerous blisters formed on the roof surface. The roof also was punctured and the insulation became soaked with rainwater over large areas. The wet insulation was replaced and the blistered area repaired before the concrete cover slab was placed.

The edges of the insulating plank had been coated with a special adhesive in accordance with the requirements of the specifications. The subcontractor was of the opinion that the adhesive used on the sides of the insulating planks was excessive and vapors from it caused the blisters. The supplier recommended and the Denver office advised that the "coating of adhesive on edges of insulation shall be omitted and that vents shall be installed. "

The roof on the service bay was placed using less adhesive. No vents were installed and blisters did not form on the roofing.

It is not conclusive whether moisture from the insulation or vapor from excessive quantities of the adhesive caused the blisters on the control bay roof or whether a combination of the two was the cause. But following a reduction in the amount of adhesive used, the blisters ceased to form.

No other difficulties were noted in the application of the roofing material on the transformer deck, river outlet roof, elevator tower roof, and elsewhere.

The cover slab on the control bay roof was damaged by wetting during a rainstorm before the concrete hardened and it later spalled extensively. The contractor in August of 1963 mopped the concrete deck with roofing asphalt and applied an armor coat of sand to protect the concrete from weathering action.

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