6 STANDARD SPECIFICATIONS 



17. Cast Iron. The maximum stresses shall not exceed , 

 in pounds per square inch, for 



Tension 2,500 Ibs. 



Compression (on blocks) 12,000 " 



Shear 1,500 " 



UNIT STRESSES: MASONRY, FOUNDATIONS 



1 8. Pressure on Walls. The pressure on walls caused by 

 beams, girders, wall plates, etc., shall not exceed the following 

 values in pounds per square inch. 



On brickwork, laid in lime mortar. ... 150 Ibs. 



" " cement mortar. 200 " 



On terra-cotta, hollow 75 



solid 150 " 



On cinder concrete 1:2:6 125 " 



On Portland cement concrete 1:2^:5. 27"> " 



1:2 :4. 350 " 

 On ordinary rubble masonry, cement 



mortar 150 " 



On first-class stone masonry, cement 



mortar 400-600 " 



19. Pressure on Foundations. The pressure on masonry 

 or foundations caused by column bases, etc., shall not exceed 

 the following values in pounds per square inch: 



Dimension stones 125 Ibs. 



Portland cement concrete 1:2}: 5 300 " 



1:2 :4 400 " 



1:2:0 (grani- 

 toid).. 600 " 

 Other values as given above (Pars. 17, 18). 



20. Pressure on Soils. The pressure on soils caused by 

 foundations, walls, etc., shall not exceed the following values in 

 tons per square foot: 



