DUST PREVENTION AND KOAD PRESERVATION. 

 Table 1. — Description of various sections of experiment No. 3. 



Section. 



Location (stations). 



Paint coat. 



Carpet coat. 



From — 



To— 



A 



12+50 

 15+00' 



17+50 

 20+00 



21 + 25 

 22+50 



25+00 

 26+50 



28+00 

 29+50 



15+00 

 17+50 



20+00 

 21+25 



22+50 

 25+00 



26+50 

 28+00 



29+50 

 30+90 





Refined coal tar. 



B 



do 



Water-gas tar preparation 



No. 2. 

 Fluxed native asphalt No. 2. 



C 



do 



D 



Water-gas tar preparation 



No. 1. 



Native asphalt emulsion 



Water-gas tar preparation 



No. 1. 



Do. 



E 



Fluxed native asphalt No. 1. 



F 



Oil-asphalt No. I. 



G 





H 



do 



Water-gas tar preparation 



No. 2. 

 Fluxed native asphalt No. 2. 



I 



do 



J. 



do 



Oil -asphalt No. 2. 









Analyses of the various materials used are given in Tables Nos. 2 

 and 3. A sample of the asphaltic emulsion was not obtained, but it 

 was the same product as was used on section No. 11 of the 1911 project 

 and reported in Circular No. 99. For a paint coat the emulsion was 

 diluted with an equal volume of water. 



From station 33+60 to station 34 + 15 the concrete was given a 

 paint coat of the crude water-gas tar, the analysis of which is given in 

 Table 2. The application was made at the rate of approximately 0.1 

 gallon per square yard. It was absorbed to a slight extent and soon 

 dried, and was distinctly evident as a brown stain on the surface when 

 last inspected. 



Table 2. — Analyses of tar products used in surface treatment of concrete. 



i Clear. 2 One-half solid, s Cloudy. * Three-fourths solid. » Two-thirds solid, e Two-fifths solid. 1 Solid. 



8 Clear. Showed 7.5 per cent insoluble in dimethyl sulphate. A 315°-350° C. fraction showed 7.5 per 

 cent, and a350°-375° C. fraction showed 17.5 per cent insoluble in dimethyl sulphate. 



9 Clear. Thisjraction, and also a 315°-350° C. fraction and a 350°-375° C. fraction each showed 7.5 per cent 

 insoluble in dimethyl sulphate. 



