476 



ADAMS. 



be obtained economically. The rock at Los Banos is andesitic with a 

 crystalline structure and is of good quality. 



The Talim quarry supplies a basaltic rock which is dense and shows 

 practically no crystalline structure to the unaided eye. It is rather friable 

 and breaks with a splintery fracture. Cnished stone from the quarry 

 usually contains a considerable admixture of softer material and dirt, 

 Especially when operations are carried on during the rainy season. The 

 old Spanish quarries near Angono .^how a dark green brecciated gabbroic 

 rock. A clean crushed stone can be obtained from it, and, although the 

 rock is brecciated and accordingly uneven in texture, it is believed that 

 it is suitable for concrete work, but not so desirable for road material. 

 When the city quarry is moved to the now location north of Angono, it 

 will supply a clean, fine grained, crushed stone of very even texture. 

 This is the best rock which can be obtained for use in Manila. 



Gvanularmctric analysis. — Crushed stone as it comes from the crusher 

 is usually very uniformly gj'aded. In this respect it differs materially 

 from gravels. Unless it contains a considerable amount of fines, it can 

 be used just as it comes fi'om the crusher. Usually the fines can be 

 washed out by pouring water over the stone when it is measured up in 

 baskets for obtaining the proper proportions in mixing concrete. 







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DIAMETER OF PARTICLES IN CENTIMETERS AND INCHES 



Fig. 15. — Geanulaemetbic Analysis of Sisiman Ceushed Stone Containing Pines. 



In fig. 15 the granularmetrie analysis of Sisiman rock is shown just 

 as it was delivered from the crusher. Percentage of voids, 37.4; 11^ per 

 cent passed the smallest sieve and 98 per cent passed the 2^-inch sieve. 

 Between these two points as plotted the analysis runs in a nearly straight 

 line. In fig. 16 the granularmetrie analysis of the same sample of stone 

 which was shown in fig. 15 is replotted excluding the fines which passed 



