OFFICE OF PUBLIC EOADS. 781 



EXPERIMENTAL WORK AT YOUNGSTOWN, OUIO.O 



The work at Youngstown, Ohio, consisted of surfacing with blast-furnace slag a 

 section of road, 2,754 feet in length, just outside of the city limits on Belle Vista 

 avenue. The slag was taken from a bank that had aged about two years and where 

 the material came from six furnaces of the same type. A steam shovel was used to 

 load the slag into gondola cars and these cars were drawn to a gravity screen, where 

 the slag was dumped into a chute and passed over the screen to separate it into proper 

 sizes. At first a 3t-inch screen was used. The finer screenings fell into one car and 

 the coarser into another. The latter material, as a rule, was soft and crumbly, and 

 was discarded. The screened slag was quite uniform in character and, after being 

 properly sized, was taken by rail to a siding 1^ miles from the road upon which it waa 

 to be used. The grading of the entire road was done by contract at 22 cents per cubic 

 yard and the total cost, including the cost of some retaining walls, was over $2,000. 

 Seven different experiments were carried out as follows: 



Experiments Nos. 1, 2, and 3 were practically regular macadam work. Experi- 

 ment Xo. 4 was regular macadam work, except that open-hearth sla^ screenings, rang- 

 ing in size from one-fourth inch to dust, were used in place of blast-furnace slag 

 screenings. Experiment No. 5 was regular macadam work, except that 5 per cent 

 of powdered quicklime was mixed with the blast-furnace slag screenings, varying in 

 size from | inch to dust. In mixing the two the screenings were measured out on a 

 mixing board and the 5 per cent of lime was spread on the top. This was turned 

 twice, and then spread upon the road, sprinkled, and rolled. Experiment No. 6 was 

 constructed of blast-furnace slag just as ordinary macadam, except that a concen- 

 trated waste sulphite liquor preparation of 1.273 specific gravity was mixed with 

 water and used to puddle the surface. In experiment No. 7 the first course of slag, 

 varying in size from 1^ inches to 'S\ inches, was laid loose to a depth of 9 inches and 

 rolled until firm. The second course, 4 inches in depth when loose, consisted of 3 

 parts of slag, varying in size from three-fourths inch to li inches, 1 part of slag screen- 

 ings varying in size from three-eighths inch to dust, and b per cent of refined coke-oven 

 tar. Aiterthis course was spread and rolled, a flush coat of tar was applied at the rate 

 of one-fourth gallon per square j^ard. A thin coat of slag screenings was then spread 

 over the road to take up any surplus tar. The cost per square yard of the various 

 experiments was, for No. 1, 4G.52 cents; No. 2, 43.34 cents; No. 3, 51.96 cents; No. 4, 

 50.21 cents; No. 5, 48.18 cents; No. 6, 61.31 cents; and No. 7, 68.45 cents. 



EXPERIMENTAL WORK AT ITHACA, N. Y. 



The experiments at Ithaca, N. Y., were conducted by the Office of Public Roads in 

 cooperation with Cornell University for the purpose of ascertaining the relative value 

 of different road binders applied in a number of ways under given conditions. In the 

 experiments where bitumens were employed as binders, an attempt was made to try 

 out all materials according to two methods of construction— the penetration method 

 and the mixing method. The roads selected for these experiments are known as the 

 Forest Home drive, which, starting at Central avenue just west of Sibley College, 

 runs east to the city limits, 3,000 feet, and state road No. 681, which runs from Ithaca 

 to Dryden and is a continuation of the Forest Home drive road. The stone used was 

 a hard blue limestone costing $1.10 per ton f. o. b. cars at Ithaca. 



Fifteen experiments were made, as follows: Ten with bituminous binders, nf which 

 6 were by the penetration method, 3 by the mixing method, and one with Kentucky 

 rock asphalt; 1 with slag macadam; 3 of concrete; and 1 of brick. The cost of con- 

 structing the various sections was excessive, owing to the shortness of the sections, 

 which was only about 300 feet, and the constant rearrangement of labor and machinery 

 which was made necessary by the variety of the work. The average cost per square 

 yard of the bituminous sections constructed by the penetration method was 50.11 

 cents, of those constructed by the mixing methods 58.51 cents, and of the Kentucky 

 rock asphalt section 83.04 cents. The cost per square yard of the slag section was 

 49.56 cents, of the concrete sections 69.63 cents, and of tlie brick section 254.96 cents. 



INSPECTION OP OBJECT-LESSON ROADS. 



During tlie last fiscal year inspections were made of twenty-eight 

 object-lesson roads at the following places: Eufala. Ala.; Opelika, 

 Ala.; Scale, Ala.; Union Springs, Ala.; Montague, C'al,; Fernandina, 



o Circular 92 of this Ofl5ce contains a complete description of these experimental 

 loads. 



