Concrete Construction Part 22

Mixing and placing 5,692 cu. yds. $0.73 $4,159.00 Plant charges 2,952.00 Plant labor 517.00 ------- ------ --------- Total 5,692 cu. yds. $0.61 $3,469.00 Total cost 5,692 cu. yds. $4.30 $24,487.00 General expenses, 10% 5,692 cu. yds. .43 2,448.00 Grand total 5,692 cu. yds. $4.73 $26,935.00

COST OF CONCRETING SHAFTS.

Materials. Quant.i.ty. Rate. Amount.

Cement 614 bbls. $1.57 $965.00 Sand 204 cu. yds. .40 82.00 Stone 521 cu. yds. 1.10 574.00 ------- ------ --------- Total 576 cu. yds. $2.82 $1,621.00 Labor.

Mixing and placing 576 cu. yds. 1.70 982.00 Plant charges, etc. 576 cu. yds. 1.36 795.00 ------- ------ --------- Total 576 cu. yds. $5.88 $3,398.00 General expenses, 10% 576 cu. yds. .59 339.00 ------- ------ --------- Grand total 576 cu. yds. $6.47 $3,737.00

COST OF CONCRETING WORKING CHAMBERS (1,566 cu. yds.).

Materials. Quant.i.ty. Rate. Amount.

Cement for concrete 1,559 bbls. $1.51 $2,446.00 Cement for mortar 442 bbls. 1.51 $694.00 Sand for both 630 cu. yds. .40 252.00 Broken stone 1,380 cu. yds. 1.10 1,518.00 ------- ------ --------- Total 1.566 cu. yds. $3.14 $4,910.00 Labor.

Top labor, mixing and placing 1,566 cu. yds. $0.78 $1,198.00 Pneumatic labor 1,566 cu. yds. 4.91 7,694.00 Compressor house labor 1,566 cu. yds. .11 180.00 ------- ------ --------- Total labor 1,566 cu. yds. $5.80 $9,072.00

Plant.

Coal at $2.40 per ton 1,566 cu. yds. .06 87.00 Concrete plant 1,566 cu. yds. .86 1,352.00 Pneumatic plant 1,566 cu. yds. .81 1,272.00 ------- ------ --------- Total plant 1,566 cu. yds. $1.73 $2,711.00 ------- ------ --------- Totals 1,566 cu. yds. $10.67 $16,693.00 ------- ------ --------- General expenses, 10% 1,566 cu. yds. 1.06 1,669.00 ------- ------ --------- Grand total 1,566 cu. yds. $11.73 $18,362.00

~COST OF FILLING PIER CYLINDERS.~--The following costs were obtained in mixing and placing concrete in steel cylinder piers. The sand and gravel were wheeled 100 ft. to the mixing board at the foot of the cylinder, mixed and shoveled into wooden skips, hoisted 20 ft. by horsepower and dumped into the cylinder. The foreman worked on the mixing board and the men worked with great energy. The costs were as follows:

Item-- Per day. Per cu. yd.

6 men wheeling materials and mixing at 15 cts. per hour 9.00 $0.45 2 men dumping skips and ramming at 15 cts.

per hour 3.00 0.15 1 team and driver at 40 cts. per hour 4.00 0.20 1 foreman at 30 cts. per hour 3.00 0.15 ----- ---- Totals $19.00 $0.95

~PIERS, CALF KILLER RIVER BRIDGE.~--The following methods and costs of building two new piers and extending three old piers with concrete are given by Mr. J. Guy Huff. The work was done by the railway company's masonry gangs. Figure 94 shows the arrangement of the several piers and the character of the work on each and Fig. 95 gives the detail dimensions of the three main piers.

The sand and aggregate, consisting of blast furnace slag, were unloaded from cars to platforms on a level with the top of rail, placed about 100 ft. south from the south end of the bridge. A cubical 1/6 cu. yd. mixer was used. This was operated by a gasoline engine, and was located on a platform about 50 ft. south of the south end pier. A tank near the mixer to supply water was elevated enough to get the desired head, and was kept filled by a pump run by another gasoline engine located down by the river bank. The cement house was located between the mixer platform and slag pile.

[Ill.u.s.tration: Fig. 94.--Diagram Arrangement of Piers, Calf Killer River Bridge.]

[Ill.u.s.tration: Fig. 95.--Details of Pier for Calf Killer Elver Bridge.]

Slag and sand were delivered to the mixer by means of wheelbarrows. The mixer was so placed that it would dump onto a platform, and the concrete could then be shoveled into a specially designed narrow-gage car. This car ran on one rail of the main track and an extra rail outside. A turnout for clearing pa.s.sing trains was provided at both ends of the bridge. The track over the bridge from the mixer had a descending grade of about 1 per cent., so that with a little start the concrete car would roll alone down to the required points on the bridge. Only in returning the empty cars to the mixer was it necessary to push them by hand, and then only for a distance of never more than 400 ft.

Over the piers on the bridge in the center of the concrete car track openings were sawed to let the concrete pa.s.s to the forms below. To get the concrete into the forms, there were used zig-zag chutes with arms about 10 ft. long, which sections were removed as the concrete in the forms was increased. These chutes were a convenience by their ends alternating from one side to the other as the arms were removed in coming up.

The cost of the concrete work was as follows:

Unloading Material.

Rate Total days Per cu. yd.

per day. worked. Total. concrete.

Foreman $3.40 5 $17.00 $0.04 11 laborers 1.36-8/10 52 71.14 .15 ----- Total for unloading material $0.19 Building Forms, Bins, Etc.

Foreman $3.40 18 $61.20 $0.14 9 carpenters 2.25 166 373.50 .81 New lumber, 23.7 M. ft.

at $17.80 421.86 .92 Old lumber, 6 M. ft. at $8.33 49.98 .11 ----- Total for building forms, bins, etc. $1.98

Cofferdam Excavation (45 cu. yds.) Foreman $3.40 8 $27.20 $0.06 9 laborers 1.15 6/10 74 86.12 .19 ----- Total for cofferdam excavation $0.25 Cofferdam Concrete (37 cu. yds.) Foreman $3.40 8 $27.20 $0.06 11 laborers 1.36 3/10 79 107.68 .23 Cofferdam lumber, 2.25 M. ft. at $20.00 45.00 .09 ---- Total for cofferdam concrete $0.38 Concrete Mixing and Placing.

Foreman $3.40 30 $102.00 $0.22 9 laborers 1.15 6/10 282 325.99 .71 Cement, 452 bbls. at $1.55 701.00 1.52 Slag, 437 cu. yds. at $0.20 87.40 .19 Sand, 220 cu. yds. at $0.30 66.00 .14 ----- Total for mixing and placing $2.78 Taking Down Forms and Clearing Up.

Foreman $3.40 13 $44.20 $0.09 11 laborers 1.17 1.43 107.31 .36 ----- Total for taking down forms, etc. $200.00 $0.45 Engineering and supervision .43 ----- Grand total, 460 cu. yds. concrete $6.46

The wages given are the average wages. The men worked a 10-hour day. The concrete was a 1-3-6 mixture. The cofferdam work was done in connection with the construction of the fourth pier, this pier being the only one coming in the bed of the river to be built entirely new. The work on this was started in water about 6 ft. deep. The 37 cu. yds. of concrete is included in the total of 460 cu. yds. in the above tabulation. By itself the cost of the cofferdam work, not including cost of cement, sand and slag was as follows:

Per cu. yd.

Total. Concrete.

Lumber $ 45.00 $1.21 Labor, excavating 113.32 3.06 Labor, concrete 134.88 3.64 ----- Total 37 cu. yds. concrete $7.91

[Ill.u.s.tration: Fig. 96.--Details of Piers for K. C., M. & O. Ry.

Bridge.]

~METHOD AND COST OF CONSTRUCTING 21 BRIDGE PIERS.~--The following account of the methods and cost of constructing 21 concrete piers for a railway bridge consisting of 20 50-ft. plate girder spans has been compiled from records kept by Mr. W. W. Colpitts, a.s.sistant Chief Engineer, Kansas City, Mexico & Orient Ry. The shape and dimensions of the piers are shown by Fig. 96 and Fig. 97 shows the construction of the forms. Sheet pile cofferdams to solid rock were used for constructing the foundations.

[Ill.u.s.tration: Fig. 97.--Forms for Piers for K. C., M. & O. Ry. Bridge.]

The 1-3-5 concrete was mixed in a Smith mixer having a batch capacity of 9 cu. ft. The mixer was located on the slope of the embankment approach, with the main track at its rear and facing a temporary material track. This temporary track turned out from the main track about 500 ft. beyond the mixer and extended diagonally down the embankment approach on a 3 per cent. grade and across the river bottom alongside the pier sites. The portion of the track in the river bottom was supported on bents of spliced ties, jetted to the rock, and wired to the cofferdam to avoid the danger of loss in case of high water. The sand and crushed rock were delivered by cars from the main line track, immediately above the mixer, and the cement was stored in a shanty at one side of the mixer. The concrete materials and machinery were, in this manner, very conveniently located for rapid work and well above the high water line. The concrete was transported to the pier sites in improvised dump boxes, set on push cars. These dump boxes were hinged longitudinally and discharged directly into the cofferdams. The grade of the temporary track carried the push cars by gravity to the cofferdams and they were returned by teams, for which purpose a straw and brush road had been built paralleling the track. As the work progressed farther into the stream, more cars were added properly to balance the work. While the concrete in the base was still fresh, a number of steel reinforcing bars, 8 ft. in length, were set in place along each end to insure a good bond between the base and shaft.

In general, the work of putting in the bases was organized so that about the same time was required in filling a cofferdam with concrete, in excavating the sand from the next, and in driving the sheet piling for the third. These three operations were thus carried on simultaneously and, although interruptions in one part of the work or the other occurred frequently, the gangs were interchangeable and no appreciable loss was suffered, except in time, because of such delays.

In piers 19 and 20, where the rock was from 17 to 19 ft. below the surface, some difficulty was encountered due to the presence of fissures in the rock, from which it was necessary to remove the sand to fill with concrete. In such cases, the larger leaks were stopped as much as possible by driving sheet piles against the outside face of the cofferdam and into the fissures, and the smaller leaks by manure in canvas bags rammed into the openings.

Upon the completion of all the bases, the forms for several shafts were set in position and the work of filling with concrete proceeded as in the case of the bases, except that a derrick erected on a flat car and stationed at the pier was utilized to raise the dump boxes in depositing the concrete in the forms. As soon as the concrete in one shaft had set sufficiently to permit of it, the forms were removed and placed on the pier ahead. Four sets of forms were used for the shafts.

The following are the average prices paid for materials and labor:

Materials.--Lumber for forms, etc., $16.50 per M. ft., B. M.; cement, Kansas Portland, $1.50 per bbl.; broken limestone, 45c per cu. yd.; sand, Arkansas River, 15c per ton.

Labor.--General foreman, $110 per month; a.s.sistant foreman, $75 per month; timekeeper, $60 per month; riveters, 35c per hour; blacksmith, 30c per hour; blacksmith a.s.sistant, 20c per hour; carpenters, 22c and 25c per hour; enginemen, 25c per hour; firemen, 20c per hour; night watchman, 20c per hour; laborers, 17c and 20c per hour; team (including driver), 40c per hour. The prices quoted for lumber, cement, limestone and sand are prices f. o. b., Louisiana, Iola, Kan., El Dorado, Kan., and Wichita, Kan.

The total and unit cost of constructing the concrete piers and abutments and of erecting the steel superstructure are given in the following tabulation. Altogether there was about 2,300 cu. yds. of concrete in the substructure, most of which, as stated above, was a 1-3-5 mixture.

Machinery and Supplies.

Concrete mixer, 20% of cost $ 152.10 Supplies, freight, hauling, setting up 505.04 -------- Total $ 657.14 Centrifugal sand pump, 20% of cost $ 27.00 Supplies, freight, hauling, setting up 277.50 Rent of traction engine to operate 83.25 -------- Total $ 387.75 Water pump and pipe, 20% of cost $ 29.00 Supplies, freight, hauling, setting up 177.32 -------- Total $ 206.32 Pile driver engine, 20% of cost $ 100.00 Supplies, freight, hauling, setting up 243.65 -------- Total $ 343.65 -------- Grand total $1,594.86 Cofferdams.

Materials, lumber and nails $1,285.26 Freight and train haul 306.33 Labor making piles 696.82 Labor driving piles 1,384.05 --------- Total $3,672.46

The sheet piling took 63,500 ft. B. M. of lumber; the cost per 1,000 ft.

B. M. for the sheet piling was then:

Materials, lumber and nails $ 20.08 Freight and haulage 4.82 Labor making piles 10.97 Labor driving piles 21.80 -------- Total $ 57.67

Forms, Platforms and Runways.

Lumber, hardware, etc. $ 224.59 Freight and train haul. 40.20 Labor making, removing and placing. 556.51 --------- Total $ 821.30 Concrete Materials.

Cement, freight, unloading and storing. $4,617.48 Sand, freight, unloading, etc. 1,336.05 Broken stone, freight, unloading, etc. 2,026.92 --------- Total $7,980.45

This gives us for 2,300 cu. yds. of concrete a cost of $3.47 per cu. yd.

for materials, including freight, storage, and unloading charges of all kinds. A line on the proportion of the cost contributed by these latter items may be got by taking the prices of the materials f. o. b. at the places of production and a.s.suming the proportions for a 1-3-5 concrete.

According to tables in Chapter II, a 1-3-5 broken stone concrete requires per cubic yard 1.13 bbls. cement, 0.48 cu. yd. sand and 0.80 cu. yd. broken stone. We have then:

1.13 bbls. cement, at $1.50 $1.69 0.48 cu. yd. sand, at 20c .10 0.80 cu. yd. stone, at 45c .36 ----- Total $2.15

This leaves a charge of $1.32 per cubic yard of concrete for freight and handling materials. The cost of mixing concrete and placing it in the forms was $3,490.87, or $1.52 per cu. yd. We have then:

Cost of concrete materials per cu. yd. $3.47 Cost of mixing and placing concrete. 1.52 ----- Total. $4.99