470 



ADAMS. 



90 

 5 lO 70 



Vy [y 50 



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MILLI¥CTERS . ( , - 

 M£SH£5 TO INCH Oajto-o-*": ^ 



SIZE or OPENINGS IN MILLIMETERS AND NUMBER OF MESHES TO THE INCH 



Fig. 10. GEANtTLAEMBTRIC ANALYSIS OF BEACH SAND FROM NEAK COBHEGIDOR. 



In fig. 10 an analysis of a beach sand from near the entrance to 

 Manila Bay is given. It shows 13 jDer cent fine gravel size, 20 per cent 

 held on a 20-niesh sieve, 32 per cent held on a 30-mesh sieve and 3.3 per 

 cent passing the 100-inesh. It is composed almost entirely of shell 

 fragments. 



All of the sands which have been analyzed grannlarmetrically show a 

 certain amount of variation. The analyses presented above, however, 

 may be regarded as fairly typical. Pasig sand, as it is used at present, 

 is not screened according to any uniform specifications. 



Efficiency. — Samples of sands from various localities above mentioned 

 were sieved on a 20-mesh sieve and the portions passing -were then sieved 

 on a 30-mesh. The sands retained on the 30-mesh were used for making 

 a series of tensile-strength briquettes in which a good quality of cement 

 was employed in the proportion of one part of cement and three parts 

 of sand. These briquettes were broken after seven days and their tensile 

 strengths compared with similar briquettes made with crushed quartz used 

 as a standard sand. The results of these tests, which, however, should be 

 regarded as incomplete, are shown in the following table : 



Comparative test of sands in tensile-strength briquettes. 



Sand screened through 20-mesh and 

 held on 30-mesh. 



Percent of 

 efficiency 

 at 7 days. 



Sangley 



Pasig 



Tarlac 



Orani 



Quingua 



Crushed quartz 



66 

 91 

 97 

 107 

 100 



