The concrete was mixed by hand. The sand and cement were mixed dry, being turned four times and spread in a layer Pebbles and broken stone previously wetted were spread over the sand and cement and the whole turned four times, the last turn being into wheelbarrows; about five common buckets of water were added during the mixing. The mixture sought was one that would ram without quaking. Two forms of rammers were used; for work next to forms a 4×6-in. rammer and for inside work 6-in diameter circular rammer weighing 20 lbs. The gang mixing and placing concrete consisted usually of:
| Item. | Per Day. | Per Cu. Yd. |
| 2 handling cement and sand | $ 3.00 | $0.10 |
| 3 filling barrows with aggregate | 4.50 | 0.15 |
| 8 mixing concrete | 12.00 | 0.40 |
| 2 shoveling concrete into barrows | 3.00 | 0.10 |
| 5 wheeling concrete to forms | 7.50 | 0.25 |
| 1 spreading concrete | 1.50 | 0.05 |
| 5 tamping concrete | 7.50 | 0.25 |
| ——— | —— | |
| Total, 26 men | $39.00 | $1.30 |
These cubic yard costs are based on 30 cu. yds. of wall completed per 8-hour day. The cost in detail of two abutments containing 254 cu. yds. was per cubic yard as follows:
| Item. | Per Cu. Yd. |
| 1.65 bbls. Portland (Germania) cement | $ 5.60 |
| 0.5 cu. yd. crushed stone | 2.07 |
| 0.24 cu. yd. gravel | 0.59 |
| 0.53 cu. yd. sand | 0.24 |
| Lumber, forms, warehouses, platforms[D] | 0.55 |
| Carpenter work[E] ($9 per M.) | 1.10 |
| Mixing and placing | 1.47 |
| 20 per cent. first cost of plant | 0.31 |
| Engineering and miscellanies | 0.31 |
| ——— | |
| Total | $12.24 |
[D] Charging ¼ of first cost of $18 per M. ft.
[E] Carpenters $3.50, laborers $1.50 per day; there was one laborer to two carpenters.
The large amount of cement 1.65 bbls. per cubic yard was due to facing the abutments with 8 ins. of 1-2 mortar. The concrete in the body of the wall was 1 cement, 2 sand, 2 gravel and 2 broken stone mixture. A dry mixture was used and this fact is reflected in the cost of ramming, 25 cts. per cu. yd. The cost of mixing was also high.
Fig. 72.—Concrete Mixing Plant for Lock Walls, Illinois & Mississippi Canal.
Piers for Taintor Gates.—The masonry at this point consisted of three piers 6×30 ft., and two abutments 30 ft. long, 6 ft. thick at base and 4 ft. thick at top, with wing walls; it amounted to 460 cu. yds. The feet of the inclined braces were set into gains in the horizontal braces and held by an 8-in. lag screw; after the posts were plumbed a block was lag-screwed at the upper end of each brace. These forms proved entirely satisfactory. The cost of the work per cubic yard was as follows: