Table 69 (continued). 



MECHANICAL PROPERTIES. 



TABLE 69. — Stone and Clay Products. 



93 



(c) Strengths of American Building Biucks.^ 



Brick — description. 



Class A (Vitrified) 



Class B (Hard burned) . . 

 Class C (Common firsts) . 

 Class D (Common) 



Absorption 

 average 

 per cent. 



5 



12 



Compression. 

 Min. ult. strength. 



kg/mm^ 



3 5° 

 2. 45 

 I .40 



I 05 



lb/in* 



5000 



3500 

 2000 

 1500 



Flexure. 

 Min. moduluj rupture. 



kg/mm' 



O.t.5 

 0.40 

 0.30 



lb/in2 



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* 



lb/ in' 



Vitrified brick 



Pressed (face) brick. 

 Pressed (face) brick. 



Common brick 



Common brick 



Terra-cotta brick. . . 



I part P.f cement : 3 parts sand. 

 I part P. cement : 3 parts sand. . 



I part lime : 3 parts sand 



I part P. cement : 3 parts sand. . 



I part lime : 3 parts sand 



I part P. cement : 3 parts sand. . 



1-95 

 1 .40 



1 .00 

 o. 70 

 0.50 



2 . ID 



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 Bmcks. 

 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. 



sand-lime 



sand-lime (German) 



paving 



acid-refractory 



silica-refractory . . . . 



kg/mm' 



2.10 



1-53 

 5.60 

 0.70 

 1 .40 



lb/in2 



3000 



2180 (av. 255 tests) 

 8000 

 1000 

 2000 



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



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

 0.70 kg/mm^ or 1000 Ib/in^. 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- 

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

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

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

 0.06 kg/mm^ or 80 Ib./in^; ordinary clay tiles 0.04 kg/mm^ or 60 Ib/in''^; porous terra- 

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

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



Smithsonian Tables. 



