34 BULLETIN 949, U. S. DEPARTMENT OF AGRICULTURE. 



A CCEPTANCE AND REJECTION OF MATERIAL. 



(15) Basis of acceptance or rejection. — Paving bricks shall not be judged for accept- 

 ance or rejection by the results of individual tests, but by the average of no less than 

 five tests. Where a lot of bricks fail to meet the required average, it shall be optional 

 with the buyer whether the bricks shall be definitely rejected or whether they may be 

 regraded and a portion selected for further test as provided in section 16. 



(16) Range of fluctuation. — Some fluctuation in the results of the rattler test, both 

 on account of variations in the bricks and in the machine used in testing, are unavoid- 

 able, and a reasonable allowance for such fluctuations should be made wherever the 

 standard may be fixed. 



In any lot of paving brick, if the loss on a test computed upon its initial weight 

 exceeds the standard loss by more than 2 per cent, then the portion of the lot repre- 

 sented by that test shall be at once resampled and three more tests executed upon it, 

 and if any of these three tests shall again exceed by more than 2 per cent the required 

 standard, then that portion of the lot shall be rejected. 



If in any lot of brick two or more tests exceed the permissible maximum, then the 

 buyer may at his option reject the entire lot, even though the average of all the tests 

 executed may be within the required limits. 



(17) Fixing of standards. — The percentage of loss which may be taken as the stand- 

 ard will not be fixed in these specifications, and shall remain within the province of 

 the contracting parties. For the information of the public, the following scale of 

 average losses is given, representing what may be expected of tests executed under 

 the foregoing specifications: 



General ^^J™" 

 mum per- 

 missible 

 loss. 



average 

 loss. 



For bricks suitable for heavy traffic . . . 

 For bricks suitable for medium traffic . 

 For bricks suitable for light traffic 



Per cent. 

 22 

 24 

 26 



Per cent. 

 24 

 26 

 28 



Which of these grades should be specified in any given district and for any given 

 purpose is a matter wholly within the province of the buyer and should be governed. 

 by the kind and amount of traffic to be carried and the quality of paving bricks 

 available. 



(18) Culling and retesting. — Where, under sections 15 and 16, a lot or portion of a 

 lot of bricks is rejected, either by reason of failure to show a low enough average test 

 or because of tests above the permissible maximum, the buyer may at his option 

 permit the seller to regrade the rejected brick, separating out that portion which he 

 considers at fault and retaining that which he considers good. When the regrading 

 is complete, the good portion shall be then resampled and retested, under the original 

 conditions, and if it fails again either in average or in permissible maximum, then the 

 buyer may definitely and finally reject the entire lot or portion under test. 



(19) Payment of cost of testing. — Unless otherwise specified, the cost of testing the 

 material as delivered or prepared for delivery, up to the prescribed number of teste 

 for valid acceptance or rejection of the lot, shall be paid by the buyer. (See also 

 section 23.) The cost of testing extra samples made necessary by the failure of the 

 whole lot or any portion of it shall be paid by the seller, whether the material is 

 finally accepted or rejected. 



