TABLE 73 (continued) 

 MECHANICAL PROPERTIES 



Stone and Clay Products 



129 



(c) Strength of American Building Bricks * 



Brick — description. 



Class A (Vitrified) 



Class B (Hard burned) . . 

 Class C (Common firsts) . 

 Class D (Common) 



Absorption 

 average 

 per cent. 



Compression. 

 Min. ult. strength. 



kg/ mm 2 



3-5° 

 2-45 

 1 .40 

 1 05 



lb/ in* 



5000 

 3500 

 2000 



Is OO 



Flexure. 

 Min. modulus rupture. 



kg/mm 2 



O.65 

 O.40 

 O.30 

 o. 20 



lb/ in 2 



900 

 600 

 400 

 300 



* 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). 



Brick or block used. 



Mortar. 



Compression.* 

 Av. ult. strength. 



kg/mm 2 



lb/in 2 



Vitrified brick 



Pressed (face) brick. 

 Pressed (face) brick. 



Common brick 



Common brick 



Terra-cotta brick . . . 



1 part P.f cement : 3 parts sand. . . . 

 1 part P. cement : 3 parts sand. . . . 

 1 part lime : 3 parts sand. . 



1 pan line : 3 parts sand 



1 part P. cement : 3 parts sand . 



1 part lime : 3 parts sand 



1 part P. cement : 3 parts sand. 



i-95 

 1 .40 

 1 .00 

 o. 70 

 o.;o 



2800 



2000 

 1400 

 1000 



700 



3000 



* 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: 



Brick. 



kg/mm 2 



lb/ in 2 



sand-lime 



sand-lime (German) 



paving 



acid-refractory .... 

 silica-refractory . . . 



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-10 (A. S. T. M. 

 Proc. XVII, I, p. 334) show compressive strengths ranging from 0.45 to 8.70 kg min- 

 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. 



