BULLETIN 10" 



U. S. DEPAETMEXT OF AGEICULTUEE. 



stniction should be careful to keep themselves informed re;^arding 

 results obtained by others engaged in similar work, and by laboratory 

 experiments. 



The earliest concrete pavement in the United States of which there 

 is reliable record was constructed at Bellefontaine. Ohio, in 1893 and 

 1894. This pavement, which contains 4.400 square yards, was con- 

 structed in two courses and in squares similar to those employed in 

 concrete-sidewalk construction. Prior to 1909 the total area of con- 

 crete pavements was comparatively small, and in most cases these 

 pavements were frankly regarded as experiments. During 1909 the 

 road officials of several communities concluded that the results already 

 obtained were sufficiently encouraging to warrant them in undertak- 

 ing the construction of concrete pavements on a larger scale, and since 

 that time a large mileage has been completed. . Wayne County. Mich., 

 was one of the first communities to adopt this form of construction, 

 and at present probably has a greater mileage of roads paved with 

 concrete than any other county in the United States. 



The majority of the concrete pavements which have been construct- 

 ed have proved entirely satisfactory where traffic conditions were not 

 unduly severe, and their use has increased rapidly. This is evidenced 

 by the following tabulation, showing the approximate number of 

 square yards of such pavements that have been placed under con- 

 tract in the United States each year beginning with 1909, and the 

 total constructed prior to 1909 : 



Cona-ete pavement constructed or under contract in the United States. 



Year. 



Streets. 



AUevs 



Total-^. 



Prior to 1909 



1909 



1910 



1911 



1912 



191.3 



1914 



1915 



1916 



1917 



1918 



1919 



1920 



Total to Jan. 1, 1921 



Sg. Ycls. 



34. 061 



32, 626 



151. 148 



291. 077 



1. 869. 486 



3. 339, 185 



10. 608. 421 



12, 050. 909 



15, 906. 801 



15. 333. 087 



12. 990. 519 



41.335.342 



29. 326. 689 



143. 269, 351 



Sq. Y'ds. 



444,864 



325. 158 



6S2. 637 



1.011.440 



3. 326. 029 



3, 946. 219 



4, 830, 604 

 5, 933, 879 



7. 395. 975 



5, 238, 062 



8, 295. 817 

 11. 086. 419 



8, 814. 782 



Sq. ra*. 

 112, 491 

 86, 825 



• 107. 874 

 136. 674 

 185. 703 

 308. 365 

 300. 138 

 612. 921 

 880. 179 



1. 200. 030 

 585, 948 



1,038.173 

 907.164 



56, 331, 885 



6, 465, 485 



Sq. Tds. 



591.416 



444.609 



941. 659 



1,439.191 



5,381.218 



7. .593. 769 



15. 739. 163 

 18. 575. 709 

 24, 182. 955 

 21.771.179 



16, 872. 284 

 53. 4-59, 934 

 39. 048, 635 



206,063,721 



The principal advantages which concrete jDavements possess may 

 be briefly stated and commented upon as follows: 



1. As far as can be judged, they are durable under ordinary sub- 

 urban and rural traffic conditions. 



