SPECIPICATIOlsrS FOR NONBITUMINOUS BOAD MATERIALS. 23 



SPECIFICATION Br-2. 



Vitrified Paving Brick, Cushion fiand, and Grouting Sand for Brick 



Pavement. 



VITRIFIED PAVING BRICK. 



All brick shall be of a size commercially known as " 3-inch brick." General. 

 They shall be thoroughly annealed, tough and durable, regular in size 

 and shape, and evenly burned. When broken, the bricks shall show a 

 dense, stonelike body, free from lime, air pockets, cracks, or marked 

 laminations. Kiln marks shall not exceed f^ of an inch, and the wearing 

 surface shall show but slight kiln marks. 



Representative samples of the brick shall meet the following require- Battler Test. 

 ments when subjected to the rattler test : 



Average loss by abrasion on one or more samples, not more than 26 

 per cent. 



Maximum difference in per cent loss by abrasion when more than one 

 representative sample is tested, not more than 8 per cent, provided, 

 however, that no sample shall show more than 28 per cent loss. 



A maximum of three tests will be used as a basis for rejection. 



The brick shall meet the following requirements : Dimensions. 



Inches. 



Length 8 to 9 



. Width 3i to 4 



Depth 2i to 3i 



Variations among brick from a single plant shall not exceed the follow- 

 ing limits : 



Inch. 



Variation in length J 



Variation in width | 



Variation in depth i 



Only brick with lugs on one side, raised not less than | of an inch Visual 

 and not more than J of an inch, shall be used. . Inspection. 



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

 radius of not less than I of an inch or 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 bricks 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 bricks 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 bricks which are cracked to a depth greater than I inch on any 

 surface, or which are cracked on the wearing surface. 



All bricks 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 bricks. 



All bricks 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. 



