CEMENT AND CONCRETE WORK 



PORTLAND CEMENT 



ON !! of the most important materials used in 

 conjunction with the foundations and ma- 

 sonry work was the Atlas Portland Cement. 

 It was required to conform to the United States Gov- 

 ernment standard, i. e., it had to be of uniform quality, 

 color ami weight, with a specifie gravity of not less than 

 3.10 and contain not more than 3 per cent, of mag 

 nesia,- nor less than 60 per cent, of lime. It had to be 

 so fine that not less than 1M) per cent . would pass through 

 a 2,500 mesh sieve, and !)() per cent, pass a 10,000 mesh 

 sieve of respectively No. 35 and 40 H.'W. gauge wire. 

 The initial set \\.i> not to take place in less than one 

 hour, nor the final set in less than three hours. 



It had to show a minimum average tensile strength 

 per square inch of 200 pounds when mixed neat; and 



after setting one day in the air until hard and in 

 water the rest of the time. 500 pounds after seven 

 days and (>.>() pounds after twenty-eight days. When 

 mixed with three parts of sand it had to show a 

 strength, after seven days, of Hi.! pounds. 



All mortar used for masonry, except for the setting 

 of limestone work, was composed of one part of Atlas 

 Portland Cement to three parts of sand. Concrete 

 consisted of one part of cement, two parts of sand 

 and five of broken stone. 



There were about 22,600 barrels of Atlas Tort- 

 land Cement used in all. At the rate of five barrels 

 to a ton this constitutes 4,520 tons, sufficient to fill 

 150 cars, or several train loads. It was furnished to 

 the various contractors requiring it at the building in 

 truck-load lots by the Atlux I'lirlltn/d Cciiirnl Co., 30 

 Broad Street, New York. 



44] 



