70 Kansas Academy of Science. 



NOTES ON KANSAS ROAD METAL. 



By F. O. Marvin, University of Kansas, Lawrence. 



I AST year, Mr. N. M. McG-illivray and Mr. E. H. Dunmire, 

 ^-^ seniors of the school of engineering of the University of Kan- 

 sas, undertook an investigation of the various kinds of stone in the 

 eastern part of the state to determine their relative value for the 

 making of good roads. The work was carried on through the year, 

 and an abstract of the results is hereby given. 



The road laboratory is equipped with a Deval machine for test- 

 ing resistance to impact and abrasion, a battery of Abbe flint-jar 

 mills for fine grinding, a hydraulic press for making briquets 

 from the fine dust, a Page cementation machine for breaking these 

 briquets, and an apparatus for the freezing test. The collection of 

 the stone was largely due to the' aid of Professor Haworth, of the 

 the Geological Survey. 



The methods followed in making the tests were in the main 

 those used by the road laboratory of the United States govern- 

 ment. The Deval machine consists of a battery of four iron cylin- 

 ders, 20 centimeters in diameter and 34 centimeters in length, set at 

 30 degrees to the axis of revolution. In each is placed five kilo- 

 grams of dried stone broken to a standard size, to pass a six-centi- 

 meter ring and returned on a three-centimeter one. The cylinders 

 are then closed with an air-tight cover and rotated at the rate of 

 33^ revolutions per minute for a total of 10,000 revolutions. The 

 per cent, of loss of weight caused by this action is taken as repre- 

 senting the value of the materials tested to resist impact and abra- 

 sion. The lower this per cent, the better the stone. In French 

 practice it was found that the best stone for road purposes lost 

 about 20 grams per kilogram, or two per cent. This figure 20 then 

 was fixed as a standard of excellence and a formula ^^^^^ adopted 

 as a coefiicient to represent the comparative value of various stone, 

 W being the weight in grams per kilogram of the loss in the Deval 

 machine. The larger this coefficient the better the stone. This 

 test has been standardized and adopted as being the best index of 

 a stone value yet devised, although not alone conclusive. 



The cementation test is designed to bring out a stone's cement- 

 ing and binding power. For this, one kilogram of stone broken to 

 small pieces is ground up to very fine dust in the porcelain jar 



