TESTS OF BOOF-SUPPOKTTNG DEVICES.
Table 3.—Results of tests of compressive strength of various forms of roof support.
Remarks.
Average construction; voids not filled. Well constructed; voids filled with small and shovel stuff.
Average construction.
In these tests the material was not con-• fined, but was free to expand laterally. (See appendix, pp. 84-86.)
In these tests the material was confined and could not expand laterally. (See appendix, pp. 86-88.)
This test was made at the Dickson Works of the Allis-Chalmers Co. in Scranton, by William Griffith.
Compression and load (tons per square foot) at end of test.
31 per cent;
Compression, load, 42.5.
46 per cent; 45 per cent; 41 per cent; 27 per cent; 63 per cent; 35 per cent; 23 per cent; 51 per cent; 33 per cent; 32.2 per cent; 20.75 per cent; load of 45 tons.
Net tons per square foot required to produce compression of—
30 per cent.
23
38.5
31.5
22.4
20 per cent.
9.5
22
20.3
9.3
1.6
5
3.5
Compression, load, 104.5.
4	13.5	35	Compression,
load, 144.
9.1	26.4	37	Compression,
load, 75.
9	33.4	  Compression,
load, 56. Compression, load, 108.
13.32	46.6	98.6 Compression,
load, 666.
24.42	308.5	  Compression,
load, 686.
5.32	10.8	25	!Compression,
5.50	22	/ load, 666.
35.52	138.7	444	Compression,
load, 668.
33.3	129	499 Compression,
load, 666.
173.8	555.4	   Compression,
load, 666.
Gradually crushed to pieces under continuous
10 per cent.
2.7
11
5.11
4
5 per cent.
1.4 5.67
1.37
5.55 5.77 1.86 ” 1.4.* 28 5.27 67
3 per cent.
0.8
3.5
3.33
3.5
1
8.9
39.3
1 per cent.
0.8
8.4
84
Cracked.
Construction tested.
Rectangular piers of mine rock. Circular pier of mine rock...
Timber crib filled with mine rock..
Pile of broken sandstone; small pieces.
Pile of small-size broken sandstone and sand.
Pile of broken sandstone; large pieces.....
Pile of coal-measures sandstone similar to No. 6.
Pile of river sand........................
Broken sandstone in cylinder.........
Broken sandstone and sand in cylinder.
(Dry coal ashes in cylinder................
\Coal ashes flushed in with water.........
Wet culm flushed in cylinder; partly dried (average of two tests).
Dry sand in cylinder......................
Wet sand flushed in and partly dried....
Concrete made of cement, sand, and gravel; 4 months old; 1 barrel Portland cement to each cubic yard of concrete (about one part cement to seven parts sand and gravel); piers 3 inches by 2.81 inches by 3.85 inches high.
No. of test.
Or
Or