Concrete Construction Part 19

1,780 bbls. natural cement at $1.068 $1,901.04 $1.545 963 cu. yds. stone at $1.619 1,559.91 1.267 53 cu. yds. screenings at $0.392 20.97 0.017 485.6 cu. yds. sand at $0.392 190.36 0.154 Miscellaneous materials 78.15 0.063 --------- ------ Totals $3,750.43 $3.046

Labor Mixing-- 254 hrs. master laborer at $0.21-7/8 $ 55.56 $0.045 4,470 hrs. labor at $0.175 782.42 0.635 Superintendence 18.20 0.015 -------- ------ Total labor mixing $ 856.18 $0.695

Labor Transporting and Placing-- 35 days overseer at $2.33-1/3 $ 81.67 $0.066 1,949 hrs. labor at $0.175 342.07 0.277 Superintendence 34.98 0.028 ------- ------ Total labor transporting and placing $ 458.72 $0.371 Grand total, labor $1,314.90 1.066 Total labor and materials $5,065.33 4.112

No charge is made under materials for rubble stone as the only cost for this was cost of handling and this is included in transporting and placing.

~BREAKWATER, BUFFALO, N. Y.~--The following methods and costs of mixing and placing some 2,561 cu. yds. of concrete are given by Mr. Emile Low, for 10 parapet wall sections and 17 parapet deck sections for a breakwater at Buffalo, N. Y.

The concrete used was a 1 cement, 1 gravel, 1 sand grit and 4 unscreened broken stone. One bag of cement was a.s.sumed to measure 0.9 cu. ft. The voids in the sand grit and gravel were 27 per cent. and in the unscreened stone 39 per cent. The hardened concrete weighed 152 lbs. per cu. ft.

[Ill.u.s.tration: Fig. 80.--Sketch Plan of Concrete Mixing Plant for Buffalo Breakwater.]

Figure 80 shows the arrangement of the mixing plant. The mixer was a 5-ft. cube mixer holding 125 cu. ft., mounted on a trestle and operated by a 912-in. horizontal engine taking steam from a 410-ft. locomotive boiler, also supplying steam to two derrick engines. The material scow contained two pockets for sand, one for gravel and one housed over for cement. Two inside cement men pa.s.sed out the bags in lots of six to one outside cement man who cut and emptied them into the charging bucket.

Three sand shovelers each loaded a 3.6 cu. ft. barrow and wheeled them tandem to the bucket, and two gravel men each loaded a 2.7 cu. ft.

barrow and wheeled them tandem to the bucket. The broken stone was loaded by eight shovelers into another bucket, also containing 21.6 cu.

ft. The two buckets were alternately hoisted and emptied into the mixer hopper, there being a dump man on the mixer who dumped the buckets and attended to the water supply. A charger put the mixer in operation and when the charge was mixed the car men dumped it into a skip resting on a small car which was then run out on the track under the mixer to the derrick which handled the skip to the work. Derrick A handled the materials from the scows and derrick B handled the mixed concrete. The force on the derricks consisted of two enginemen, four tagmen and the fireman.

The ten parapet wall sections containing 841 cu. yds. were built in 46 hours, making 17 batches of 1.07 cu. yds., or 18.2 cu. yds. placed per hour. The 17 parapet deck sections containing 1,720 cu. yds. were built in 88 hours, making 18.8 batches of 1.08 cu. yds., or 19.5 cu. yds.

placed per hour. For the parapet deck work the force was increased by 2 men handling materials and 1 man on the mixer. The labor cost of mixing and placing the concrete was as follows:

Per Per Loading Gang-- day. cu. yd.

1 a.s.sistant foreman 2.00 $0.011 3 cement handlers 5.25 0.029 3 sand shovelers 5.25 0.029 2 gravel shovelers 3.50 0.020 8 stone shovelers 14.00 0.076 1 hooker on 1.75 0.010 ------ ------ Totals $31.75 $0.175

Mixer Gang-- 1 dumpman $ 1.75 $0.010 1 charging man 1.75 0.010 2 car men 3.50 0.020 2 enginemen at $3.25 6.50 0.035 4 tagmen at $2 8.00 0.044 1 fireman 2.00 0.011 ------ ------ Totals $23.50 $0.130

Wall Gang-- 1 Signalman $ 1.75 $0.010 1 dumper 1.75 0.010 6 shovelers at $2 12.00 0.065 4 rammers 7.00 0.038 1 foreman 4.00 0.022 ------ ----- Totals $26.50 $0.145 Grand totals $81.75 $0.450

[Ill.u.s.tration: Fig. 81.--Concrete Blocks for Pier at Port Colborne Harbor.]

[Ill.u.s.tration: Fig. 82.--Forms for Molding Blocks, Port Colborne Harbor Pier.]

[Ill.u.s.tration: Fig. 83.--Device for Handling Blocks, Port Colborne Harbor Pier.]

~PIER CONSTRUCTION, PORT COLBORNE, ONT.~--In constructing the new harbor at Port Colborne, Ont., on Lake Erie, the piers consisted of parallel rows of timber cribs set the width of the pier apart and filled in and between with stone blasted and dredged from the lake bottom in deepening the harbor. The tops of the cribs terminated below water level and were surmounted by concrete walls set on the outer edges. These walls were filled between with stone and the top of the filling was floored part way or entirely across, as the case might be, with a thick concrete slab. The footings of the walls to just above the water level were made of concrete blocks 447 ft., constructed as shown by Fig. 81. The wall above the footing course and the floor slab were of concrete molded in place. The concrete work consisted of molding and setting concrete blocks and of molding concrete wall and slab in place.

The blocks were molded on sh.o.r.e, s.h.i.+pped to the work on scows and set in place by a derrick. Figure 82 shows the construction of the forms for molding the blocks; the bottom tie rods pa.s.sed through the part.i.tions forming the ends of the molds. The sides were removed in 48 hours and used over again. Figure 83 shows the hooks used for handling the molded blocks. Considerable trouble was had in setting these blocks level and close jointed, owing to the difficulty of leveling up the stone filling under water.

[Ill.u.s.tration: Fig. 84.--Scow Plant for Mixing and Placing Concrete, Port Colborne Harbor Pier.]

The ma.s.s concrete was mixed and placed by the scow plant, shown by Fig.

84. The scow was loaded with sufficient sand and cement for a day's work and towed to and moored alongside the pier. Forms were set for the wall on top of the block footing. These forms were placed in lengths of 60 to 75 ft. of wall and resembled the block forms with part.i.tions omitted.

The bottoms of the rear uprights were held by being wedged into the grooves in the blocks, and the bottoms of the front uprights were held by bolts resting on top of the blocks. The tops of the uprights were held together across the wall by tie bolts. The forms being placed, the mode of procedure was as follows:

The crusher fed directly into a measuring box. After some 6 ins. of stone had run into the box the door of the crusher spout was closed. A wheelbarrow load of sand was spread over the stone in the box and over this were emptied and spread two or three bags of cement. Another layer of stone and then of sand and of cement were put in and these operations repeated until the box was full. The box was then hoisted and dumped into the hopper of a gravity mixer of the trough type which ran along a track on the scow and fed directly into the forms. The gang worked consisted of 1 foreman, 1 derrickman and 18 common laborers. This gang placed from 65 to 75 cu. yds. of concrete per day at a labor cost of 50 cts. per cu. yd.

[Ill.u.s.tration: Fig. 85.--Cross-Section of Concrete Pier, Superior, Wis.]

~CONCRETE BLOCK PIER, SUPERIOR ENTRY, WIS.~--The methods and cost of constructing a concrete pier 3,023 ft. long and of the cross-section shown by Fig. 85 at Superior entry, Wisconsin, are given in the following paragraphs.

_Molds and Molding._--About 80 per cent. of the concrete was deposited in molds under water, according to a plan devised by Major D. D.

Galliard, corps of engineers. In brief the concrete was built in place in two tiers of blocks, the lower tier resting directly on piles and being entirely under water and the upper tier being almost entirely above water. As shown by Fig. 85, a pile trestle was built on each side of the proposed pier and a traveler for raising and lowering the molds spanned the s.p.a.ce between trestles.

The molds were bottomless boxes built in four pieces, two sides and two ends, held together by tie rods. Fig. 86 shows an end and a side of one of the shallow water molds and Fig. 87 shows in detail the method of fastening the end to the side. It will be seen that the 1-in.

turnbuckle rods pa.s.s through the ends of beams that bear against the outside of the mold. These tie rods have eyes at each end in which rods with wedge-shaped ends are inserted. The molds were erected on the trestle by a locomotive crane and were then lifted by the mold traveler, carried and lowered into place. The largest one of these molds with its iron ballast, weighed 40 tons. To remove a mold, after the block had hardened, the nuts on the wedge-ended rods were turned, thus pulling the wedge end from the eye of the tie rod and releasing the sides of the mold from the ends. The locomotive crane then raised the ends and sides, one at a time, and a.s.sembled them ready to be lowered again for the next block. The time required to remove one of these 40-ton molds, rea.s.semble and set it again rarely exceeded 60 minutes and was sometimes reduced to 45 minutes.

[Ill.u.s.tration: Fig. 86.--Mold for Concrete Block for Pier at Superior, Wis.]

The concrete was deposited in alternate blocks and the molds described were for the first blocks; for the intermediate blocks molds of two side pieces alone were used, the blocks already in place serving in lieu of end pieces. The two side pieces were bolted together with three tie rods at each end; the tie rods were encased in a box of 1-in. boards 44 ins.

inside which served as a strut to prevent the sides from closing together and as a means of permitting the tie rods to be removed after the concrete had set. The mold was knocked down just as was the full mold described above and the boxes encasing the tie rods were left in the concrete.

[Ill.u.s.tration: Fig. 87.--Device for Locking End and Side of Mold for Concrete Blocks for Pier at Superior, Wis.]

An important feature was the device for handling the molds; this, as before stated, was a traveler, which straddled the pier site, it having a gage of 31 ft. It carried a four-drum engine, the drums of which were actuated, either separately or together, by a worm gear so as to operate positively in lowering as well as in raising. The load was hung from four hooks, depending by double blocks and 5/8-in. wire rope from four trolleys suspended from the trusses of the traveler; this arrangement allowed a lateral adjustment of the mold. The hoisting speed was 6 ft.

per minute and the traveling speed 100 ft. per minute. The locomotive crane also deserves mention because it was mounted on a gantry high enough to permit material cars to pa.s.s under it on the same trestle, thus making it practicable to work two cranes.

[Ill.u.s.tration: Fig. 88.--Bucket for Depositing Concrete Under Water for Pier at Superior, Wis.]

The concrete was received from the mixer into drop bottom buckets of the form shown by Fig. 88. The buckets were taken to the work four at once on cars, and there lifted by the locomotive crane and lowered into the mold where they were dumped by tripping a latch connected by rope to the crane. To prevent the concrete from was.h.i.+ng, the open tops of the buckets were covered with 34 ft. pieces of 12-oz. canvas in which were quilted 110 pieces of 1/1613-in sheets of lead. Two covers were used on each bucket and were attached one to each side of the bucket top so as to fold over the top with a lap. This arrangement was entirely successful for its purpose.

_Concrete Mixing._--The proportions of the subaqueous concrete were 1-2-5 by volume, or 1-2.73-5.78 by weight, cement being a.s.sumed to weigh 100 lbs. per cu. ft.; the proportions of the superaqueous concrete were 1-3.12-6.25 by volume, or 1-3.41-7.22 by weight. The dry sand weighed 109.2 lbs. per cu. ft., the voids being 35.1 per cent.; the pebbles weighed 115.5 lbs. per cu. ft., the voids being 31 per cent.

The pebbles for the concrete were delivered by contract and were unloaded from scows by clam-sh.e.l.l bucket into a hopper. This hopper fed onto an endless belt conveyor which delivered the pebbles to a rotary screen. Inside this screen water was discharged under a pressure of 60 lbs. per sq. in. from a 4-in. pipe to wash the pebbles. From the screen the pebbles pa.s.sed through a chute into 4-cu. yd cars which were hauled up an incline to a height of 65 ft. by means of a hoisting engine. The cars were dumped automatically, forming a stock pile. Under the stock pile was a double gallery or tunnel provided with eight chutes through the roof and from these chutes the cars were loaded and hauled by a hoisting engine up an inclined trestle to the bins above the concrete mixer. The sand was handled from the stock pile in the same manner. The cement was loaded in bags on a car in the warehouse, hauled to the mixer and elevated by a sprocket chain elevator.

Chutes from the bins delivered the materials into the concrete mixer, which was of the Chicago Improved Cube type, revolving on trunnions about an axial line through diagonal corners of the cube. The mixer possessed the advantage of charging and discharging without stopping. It was driven by a 710-in. vertical engine with boiler. The mixer demonstrated its ability to turn out a batch of perfectly mixed concrete every 1-1/3 minutes. It discharged into a hopper provided with a cut-off chute which discharged into the concrete buckets on the cars.

_Labor Force and Costs._--In the operation of the plant 55 men were employed, 43 being engaged on actual concrete work and 12 building molds and appliances for future work. The work was done by day labor for the government and the cost of operation was as follows for one typical week, when in six days of eight hours each, the output was 1,383 cu.

yds., or an average of 230 cu. yds. per day. The output on one day was considerably below the average on account of an accident to the plant, but this may be considered as typical.

Pebbles from Stock Pile to Mixer-- Per cu. yd.

4 laborers at $2 $0.0348 1 engineman at $3 0.0131 Coal, oil and waste at $1.03 0.0043

Sand from Stock Pile to Mixer-- 5 laborers at $2 $0.0434 1 engineman at $2.50 0.0109 Coal, oil and waste at $0.82 0.0035

Cement from Warehouse to Mixer-- 5 laborers at $2 $0.0434

Mixing Concrete-- 1 engineman at $2.50 $0.0109 1 mechanic at $2.50 0.0108 Coal, oil and waste at $1.29 0.0056

Transporting Concrete-- 4 laborers at $2 $0.0348 1 engineman at $3 0.0130 Coal, oil and waste at $0.66 0.0028

Depositing Concrete in Molds-- 4 laborers at $2 $0.0348 1 engineman at $3 0.0130 1 rigger at $3 0.0130 Coal, oil and waste at $1.18 0.0051

a.s.sembling, Transporting, Setting and Removing Molds-- 4 laborers at $2 $0.0347 1 engineman at $3.25 0.0141 1 carpenter at $3 0.0130 1 mechanic at $2.50 0.0109 Coal, oil and waste at $1.39 0.0060

Care of Tracks-- 1 laborer at $2 $0.0086 1 mechanic at $2.50 0.0109

Supplying Coal-- 3 laborers at $2 $0.0260