MASONRY 



309 



Sand. Dry sand weighs from 80 to 115 Ib. per cu. ft. Moist 

 sand occupies more space and weighs less per cubic foot than 

 dry sand. 



The voids of ordinary sand range from one-fourth to one- 

 half of the volume. The more uneven the grains in size, the 

 smaller the percentage of voids. 



The fineness of sand is measured by determining the per- 

 centage passing through five sieves, the first having 400 meshes, 

 the second 900, the third 2,500, the fourth 6,400, and the fifth 

 28,900 per sq. in. When the grains range from f to ^ in., the 

 sand is called coarse; when from & to ^ in., fine; and when 

 from ,fo to gfc in., very fine. When it is composed of sizes vary- 

 ing within these limits it is termed mixed sand. 



MORTALS 



Lime mortar is ordinarily composed of 1 part of slaked lime 

 to 4 parts of sand. This kind of mortar should not be used in 

 foundation work below the water-line, or in continually damp 

 situations; neither should it be used in freezing weather. 



MATERIALS REQUIRED PER CUBIC YARD OF MORTAR 



Portland-cement mortar is composed of Portland cement and 

 sand in proportions that vary from 1 part of cement and 1 part 

 of sand to 1 part of cement and 6 parts of sand, this variation 

 being according to the strength of the mortar desired. The 

 common proportion for ordinary masonry is 1 part of cement 

 to 3 parts of sand. For pointing face joints, 1 part of cement 

 to either 1 or 2 parts of sand is used. 



