METHODS OF SAMPLING AND TESTING HIGHWAY MATERIALS 13 
54. Briquets that are manifestly faulty or which give strengths differing inore 
than 15 per cent from the average value of all test specimens made from the 
same sample and tested at the same period, shall not be considered in determin- 
ing the tensile strength. 
STORAGE OF TEST SPECIMENS 
55. The moist closet may consist of a soapstone. slate, or concrete box, or a 
wooden box lined with metal. The interior wall surfaces of all closets shall be 
covered with felt or broad wicking kept wet. The bottom of the moist closet 
shall be covered with water to a depth of at least 2 inches. 
5$. All test specimens, immediately after molding, shall be kept in the molds on 
plane plates in the moist closet for from 20 to 24 hours in such manner that the 
upper surfaces shall be exposed to the moist air. 
57. The briquets shall then be removed from the molds and immersed in clean 
water in storage tanks constructed of noncorroding material. 
2. METHODS OF SAMPLING STONE, SLAG. GRAVEL, SAND, 
AND STONE BLOCK FOR USE AS HIGHWAY MATE- 
RIALS, INCLUDING SOME MATERIAL-SURVEY 
METHODS 
T. M. standard method t ;) serial designation D 75-22. except as indicated. See p. 1) 
1. Sarni'les of all materials for test upon which is to be based the acceptance 
or rejection of the supply shall be taken by the engineer or his authorized 
representative. Samples for inspection or preliminary test may be submitted by 
a producer or owner of the supply. 
SAMPLING OF STONE 
A. SAMPLING OF STONE FROM LEDGES OR QUARRIES FOR QUALITY 
2. The ledge or quarry face shall be inspected closely to determine any varia- 
tion in different layers. Any difference in color or structure shall be observed, 
and if accessary to secure unweathered specimens, pieces broken from different 
layers. 
3. I a i For standard stone test, separate samples shall be taken of at least 30 
pounds each of fresh unweathered specimens from all layers that appear to 
vary in color or structure. When more than one piece is taken the minimum size 
shall be 2 inches, except that there shall be one piece of each sample of a 
minimum size of 4 by 5 by 3 inches, on which the bedding plane is marked, and 
which shall be free from seams or fractures to be used in the toughm e 
compression test. 
1 1>\ The sample for concrete test will depend on the kind of tests to be made 
and the number of specimens necessary. 
4. In addition to the general information acccompanying all samples, samples 
from local ledges not commercial sources shall contain the following: Name of 
owner, approximate quantity available (if quantity is very large this can be 
recorded as practically unlimited), amount and character of overburden or strip- 
ping, haul to nearest point on road where the material is to be used, character 
of haul (kind of road and grade), also some detailed record of the extent and 
location of the material represented by each sample. For this purpose a sketch, 
plan, and elevation showing the thickness and location of the different layers 
is recommended. 
B. SAMPLING OF STONE FROM COMMERCIAL QUARRIES 
5. Where practical, samples from commercial cptarries shall be taken from 
the ledge or quarry face and the same procedure shall be followed as when 
sampling local ledges. 
6. At the plant, the following factors affect the size of broken stone: Size and 
shape of screen openings, length of screen sections, the angle of screen with 
horizontal, the speed of screen rotation, and the rate at which the screen is 
fed. A general inspection and record of these conditions shall be made. The 
sample shall be taken preferably from cars or boats while loading from stock 
