TABLE 69 (continued). 



MECHANICAL PROPERTIES- 



TABLE 69. Stone and Clay Products. 



93 



* After A. S. T. M. Committee C~3, Report 1913, and University laboratories' tests 

 for Committee C~3 (Johnson, p. 281). 



(d) STRENGTH IN COMPRESSION OF BRICK PIERS AND OF TERRA-COTTA BLOCK PIERS. 

 Tabular values are based on test data from Watertown Arsenal, Cornell University, 

 U. S. Bureau of Standards, and University of 111. (Moore, p. 185). 



* Building ordinances of American cities specify allowable working stresses in com- 

 pression over bearing area of 12.5 per cent (vitrified brick) to 17.5 percent (common 

 brick) of corresponding ultimate compressive strength shown in table. 



t P. denotes Portland. 



(e) STRENGTH OF COMPRESSION OF VARIOUS BRICKS. 



Reasonable minimum average compressive strengths for other types of brick than 

 building brick are noted by Johnson, "Materials of Construction," pp. 289 ff., as follows: 



The specific gravity of brick ranges from 1.9 to 2.6 (corresponding to 120 to 160 lb/ft 3 ). 



Building tile: hollow clay blocks of good quality, minimum compressive strength: 

 0.70 kg/mm 2 or 1000 lb/in 2 . Tests made for A. S. T. M. Committee C-io (A. S. T. M. 

 Proc. XVII, I, p. 334) show compressive strengths ranging from 0.45 to 8.70 kg/mm 2 

 or 640 to 12,360 lb/in 2 of net section, corresponding to 0.05 to 4.20 kg/mm 2 or 95 to 6000 

 lb/in 2 of gross section. Recommended safe loads (Marks, "Mechanical Engineers' 

 Handbook," p. 625) for effective bearing parts of hollow tile: hard fire-clay tiles 

 0.06 kg/mm 2 or 80 lb./in 2 ; ordinary clay tiles 0.04 kg/mm 2 or 60 lb/in 2 ; porous terra- 

 cotta tiles 0.03 kg/mm 2 or 40 lb/in. 2 The specific gravity of tile ranges from 1.9 to 2.5 

 corresponding to a weight of 120 to 155 lb/ft 3 . 



SMITHSONIAN TABLES. 



