266 



Journal of Agricultural Research 



Vol. X, No. 5 



Table I. — Mechanical analysis of natural sand 



The fine sand contained about 10 per cent that passed a 200-inesh sieve. 



The sands graded as above then were recombined into 60 different 

 combinations of coarse, medium, and fine, as shown in Table II, in which 

 the equivalent mechanical analysis of each combination is also shown. 

 The resulting sands were made up into standard mortar briquettes and 

 2 by 2 inch cylinders, using a mixture composed of i part of cement to 

 2>2 parts of sand. All the batches were brought to as nearly the same 

 consistency as it was possible to judge by the eye, which necessitated the 

 use of \arying percentages of water. Specimens were stored in moist 

 air one day and in water six days and then were tested to determine 

 their hardness, toughness, tensile strength, and crushing strength. 



Table II. — Proportion of artificially graded sands 



Laboratory No. 



I 



2 



3 

 4 

 5 

 6 



7 

 8 



9 

 10 

 II 

 12 

 13 

 14 

 15 

 16 



17 

 18 



19 

 20 

 21 

 22 

 23 



