Some Tests of Paving Brick. 
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“6. Condition of the Charge: The bricks composing the charge 
shall be thoroughly dried before making the test.* 
‘‘7. Calculating the Results: The loss shall be calculated in per- 
centages of the weight of the dry brick composing the charge, and no 
result shall be considered as official unless it is the average of two 
distinct tests, made on separate charges of brick. 
For the basis of comparison, it can be stated that one city in Ohio 
a few years ago had fourteen samples of paving brick tested and the 
average loss was 18.97 per cent, their range being from 15.60 to 24.35 
per cent. These brick were about 3x4x9 inches. It must be stated that 
brick 2x4x8 inches will lose as much as 6 per cent more than blocks. 
From tests made at the University of Texas it is clear that a com- 
parison of blocks from one company and brick from another is not 
a fair test, because testimony is conclusive that the larger the speci- 
men, the less the per cent of wear they indicate under rattler tests. 
A perfectly fair test of say six varieties of brick would be given by re- 
quiring all of them to be of the same size and by using one or two 
specimens in each run of the rattler. 
*“Soft brick saturated in water to 8 per cent, lost only 67 per cent, as much 
as brick from the same lot tested dry.” It has been clearly proved that dry 
brick lose more than wet ones, but the reason for this difference has not been 
established. It is reasonable to suppose that different kinds of brick having 
different percentages of absorption should have different losses for different 
degrees of moisture. 
**There is considerable difference in practice as to the methods of consider- 
ing broken brick, some experimenters counting all pieces weighing 1 less than 
1 pound as abraded material; while others put the limit at half a pound. The 
latter is apparently the more common. 
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