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column sizes, thickness of slabs and sizes of beams and 

 girders are generally made part of the specifications. 

 These can be replaced by some special system guaranteed 

 to be as good as the one shown by the architects. 



Forms: The forms should be of such a character that 

 after they are removed all slabs will have plane level sur- 

 faces, all beams, girders, columns and walls will line up 

 true to a plumb line and have the proper elevations called 

 for. Wherever a surface finish is to be used rough lum- 

 ber can be used on that side. The size, thickness and 

 quality of the lumber is generally left to the discretion 

 of the contractor, as it is to his interest to use the best 

 quality of lumber of the necessary dimensions. 



The forms should not be removed until the concrete has 

 become hard enough to sustain its own weight and the 

 probable weight liable to be superimposed. Shores should 

 be left in place at least 4 weeks. 



Before concreting, all forms should be cleaned of saw- 

 dust, blocks, shavings, dirt, dust, holes patched with 

 tin, oiled and sprinkled. Holes should be left in the bot- 

 tom of columns to clean out the pieces of wood and saw- 

 dust that collect in same. 



Concrete: The concrete is required to be mixed by 

 volume; 1:3:6 being required for footings and 1:2:4 for 

 structural members, 1:2 for finish and this should never 

 be less than % in. Water enough to make a pasty mix- 

 ture is required. Never use such an amount of water 

 that the cement and sand runs away from the stone or 

 gravel. (Note. By 1:3:6 is meant 1 part cement, 3 parts 

 sand and 6 parts by volume of broken stone or gravel). 

 It is advisable to test the mixture for maximum density. 



Portland Cement: Only high grade, established brands 

 of cement, delivered at least 12 days before being used 

 and passing the following tests should be used: 



Specific gravity of the cement, thoroughly dried at 100 

 C. to be at least 3.10. 



Fineness: It should leave a residue of not more than 8% 

 on a No. 100 and not more than 25% on a No. 200 sieve. 



Time of Setting: Initial set not less than 30 minutes; 

 hard set not less than 1 hour, nor more than 10 hours. 



Tensile Strength: A briquette of 1 sq. in. cross section 

 shall have the following strengths: 



Neat Cement. Strengl '- 



24 hours in moist air 150 to 200 Ib. 



7 days (1 day in moist air, 6 days in water). .450 to 550 Ib. 

 28 days (1 day in moist air, 27 days in water) 550 to 650 Ib. 



