22 



BULLETIN 704, U. S. DEPARTMENT OF AGRICULTUEE. 



Tisnal 

 Inspection. 



If the edges of the brick are i-ounded, the radius shall not exceed -pg of 

 an inch. 



Only bricks with lugs or projections on one side, raised not less than i 

 of an inch, nor more than J of an inch, shall be used. 



The ends of the brick shall have either a semicircular groove with a 

 radius of not less than | of an inch nor more than I of an inch, or a 

 bulge of at least tV of an inch. 



The name or trade-mark of the manufacturer, if shown on the brick, 

 shall be recessed and not raised. 



The brick shall be subjected to inspection subsequent to delivery at 

 the place of use, prior to and during laying, in order to cull out and 

 reject upon variations from the general and dimensions clauses and 

 upon the following grounds : 



All brick which are broken through, or chipped in such manner that 

 neither wearing surface remains substantially intact, or in such manner 

 that the lower or bearing surface is reduced in area by more than one- 

 eighth. 



All brick which are cracked to a depth greater than | inch on any 

 surface, or which are cracked on the wearing surface. 



All brick which are so offsize or so misshaped, bent, twisted, or kiln 

 marked that they will not form a proper surface or align properly with 

 other brick. 



All brick which are obviously too soft and too poorly vitrified to en- 

 dure street wear. 



SAND FOR CUSHION. 



The sand shall pass a J-inch laboratory screen and shall be well 

 General. graded from coarse to fine. The material removed by the elutriation 



test, consisting chiefly of clay and loam, shall not exceed 5 per cent by 

 weight, 



SAND FOR GROUTING. 



Methods of 

 Testing. 



The sand shall consist of clean, hard, durable, uncoated stone particles, 

 preferably siliceous, and free from lumps of clay and all organic matter. 



It shall be well graded from coarse to fine and, when tested by means 

 of laboratory sieves, shall meet the following requirements : 



Per cent. 



Passing 10-mesh sieve 100 



Passing 20-mesh sieve, not less than 80 



Passing 100 mesh sieve, not more than 10 



Not more than 5 per cent by weight shall be removed by the elutriation 

 teet. 



When the sand is mixed with Portland cement in the proportion of 1 

 part of cement to 3 parts of sand by weight, according to standard 

 methods of making 1 : 3 mortar briquets, the resulting mortar at the 

 age of 7 and 28 days shall have a tensile strength of at least 75 per cent 

 of that developed in the same time by mortar of the same proportions 

 and consistency, made of the same cement and Ottawa sand. 



Preliminary acceptance samples shall be subjected to both 7 and 28 

 day tests, and acceptance based thereupon. Samples tested during the 

 progress of the work will be accepted on the basis of the 7-day test. 



Tests of the physical properties of the brick and sand shall be made 

 in accordance with the following methods : 



1. Rattler Test, A. S. T. M. Standard, C7-15. 



2. Grading of Sand, U. S. Department of Agriculture Bulletin 555, p. 33. 

 S. Elutriation Test for Sand, U. S. Department of Agriculture Bulletin 



555, p. 32. 

 4. Mortar Tensile Strength Test for Sand, A. S. T. M. Standard, C9-17. 



