TESTS OF PHILIPPINE ROAD MATERIALS. 



By Geoege I. Adams. 

 (From the Division of Mines, Bureau of Science.) 



Sometime ago the engineer of the city of Manila requested that the 

 division of mines of the Bureau of Science find a quarry site which would 

 supply a superior quality of stone for macadamizing the streets. The im- 

 portance of this problem will be seen when it is realized that the city uses 

 each 3'ear in surfacing streets about 50,000 cubic meters of crushed 

 stone, which costs delivered in^Manila about ?=2.50 per cubic meter. The 

 quality is not satisfactory and any improvement in the quality of the 

 material used would be evident in the better character of the streets and 

 a saving in the cost of maintenance. 



Alrasion machine. — It is obvious that in recommending a change of 

 the quarry site one should not trust simply to his judgment, but should 

 be able to base his recommendations on. reliable tests. When geologic 

 work was begun for the purpose of finding a better stone, there were no 

 appliances in the Islands for testing stone for use as road material, and 

 it seemed undesirable to resort to the only remaining method of making 

 a practical test by macadamizing certain streets with different materials 

 available, and waiting for the results of actual wear to show which mate- 

 rial is the most desirable. A properly equipped laboratory should be sup- 

 plied with apparatus for submitting stone to the abrasion test and 

 determining its cementing value, toughness, absorption, hardness, specific 

 gravity, and strength. Most of this apparatus is relatively expensive, and 

 some of it, being of special design, can not be constructed easily. For the 

 abrasion test, however, which is the one which most closely corresponds to 

 the conditions of actual wear, a machine that can be constructed readily is 

 required and accordingly one was designed. Castings were made in Ma- 

 iiila, and the machine was completed and set up by the engineer of 

 this Bureau. The Devall type of machine first constructed in Prance 

 and accepted and used by the Eoad Material Laboratory of the United 

 States Department of Agriculture at Washington, was selected, in order 

 that tests might be carried on in conformity with accepted standards, 



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