SAMPLING AND TESTING HIGHWAY MATERIALS. 



17 



liquid above the sand. A good idea of the quality of the sand can be formed earlier 

 than 24 hours, although this period is believed to give best results. 



(2) If the solution resulting from this treatment is colorless, or has a light yellowish 

 color, the sand may be considered satisfactory in so far as organic impurities are con- 

 cerned. On the other hand, if a dark-colored solution of a color deeper than that 

 indicted is produced, the sand should not be used in high-grade concrete such as that 

 required in roads and pavements, or in building construction. 



(3) Color values: While it is not practicable to give exact values for the reduction 

 in strength corresponding to the different colors of solution, the tests made thus far 

 show this relation to be about as follows: 



Color No.i 



Redaction 

 in com- 

 pressive 

 strength 

 of 1 : 3 mor- 

 tar at 7 and 

 28 days. 





Per cent. 

 None. 

 10 to 20. 

 15 to 30. 

 25 to 50. 

 50 to 100. 



Figure 2 











1 See Plate V, Proceedings of the American Society for Testing Materials, vol. xix, part 1, Report of 

 Committee C-9, for Color Scale. 



(4) Washing dirty sands has the effect of greatly reducing the quantity of organic 

 impurities. However, even after washing, sands should be examined in order to 

 determine whether the organic impurities have been reduced to harmless proportions. 



The following list includes sufficient apparatus for making five field tests at a time: 

 Five 12-oz. graduated prescription bottles; Stock of 3 per cent solution of sodium 

 hydroxide (dissolve 1 oz. of sodium hydroxide in enough water to make 32 oz.) 



This test does not give satisfactory results when lignite is present in the sand. 



16. TEST FOR MORTAR MAKING QUALITY OF FINE AGGREGATES. 



(1) When the fine aggregate 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 



strength in tension and compression of at least i 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. 



(2) 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 

 shall be accepted on the basis of the 7-day test. 



17. STANDARD SPECIFICATIONS AND TESTS FOR PORTLAND CEMENT. 



(A. S. T. M. Standard Method, Serial Designation: C 9-17.) 

 SPECIFICATIONS. 



(1) Portland cement is the product obtained by finely pulverizing clinker produced 

 by calcining to incipient fusion an intimate and properly proportioned mixture of 

 argillaceous and calcareous materials with no additions subsequent to calcination 

 excepting water and calcined or uncalcined gypsum. 



4 It is recommended that the strength ratio be 100 per cent for this purpose. 

 29465°— 21— Bull. 949 2 



