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DOCK ENGINEERING.
In an experiment by Mr. Sutcliffe with a conerete block cut from a dock
wall at Liverpool, and composed of 8 parts of gravel and broken brick to 1
of Portland cement, with rubble burrs incorporated, the size of the block
being 25 inches wide by 23 inches deep, and the clear span 12 feet, fracture
resulted from a central concentrated load of 3'25 tons, giving a coefficient of
5 tons for the unit beam.
Sir Benjamin Baker’s experiments,* in which the weight of the beam
itself was included, yielded the following unit breaking weights : —
4'85 tons for . . . 8 to 1 conerete.
9 ,, .. . 6 to 1 ,,
13 „ ... 4 to 1 ,,
18 ,, ... pure cement.
Some Sample Compositions of Conerete.
1. At Arbroath, used by Mr. W. Dyce Cay, in 1887, for adock entrance—
1 Portland cement, 7 sand, gravel, and broken stone.
2. At Sydney, used by Mr. C. W. Young, in 1883, for a graving dock—
1 Portland cement, 1'5 sand,
3’61 bluestone, gauged tlirough a 2J-inch ring.
3. At Belfast, by Mr. W. Redfern Kelly, in 1888, for
(a) For foundations in tideways—
1 Portland cement,
2 sand,
(6) For hearting to walls—■
1 Portland cement,
2 sand,
(c) For facing to walls—-
1 Portland cement,
1 sharp sand,
a graving dock.
1J gravel,
IJ whinstone metal.
21 whinstone metal,
3; coarse gravel.
3 fine gravel.
4. At Newport, Mon., by Mr. G. D. Pickwell, in 1889, for a graving dock_______
1 Portland cement,
10 broken steel slag, weighing 26 feet per ton, in pieces not larger than
2|-inch cubes for bulk and f-inch cubes for face work—in both cases
unscreened from dust.
5. At Greenock, by Mr. W. R. Kinipple, between 1878-86, for dock walls________
1 Portland cement, 3 ballast,
3 coarse sand, 6 large stones.
6. At Ardrossan, by Mr. R. Robertson, circa 1889, for dock walls.
(a) For rubble conerete—
1 Portland cement, 1’4 gravel,
2 broken stone, passed through 2'2 sand,
screen with 2-inoh mesh.
(6) For conerete in bags—
1 Portland cement,
2'2 broken stone,
1'4 gravel,
1'2 sand.
* Afin, Proc. Inst. G.E., vol. cxi., p. 95.