10 



BULLETIN 313^ U. S. DEPAETMEXT OF AGEICTJLTUEE. 



structed of Portland cement concrete may frequently be advan- 

 tageously used. Concrete curbs may be constructed alone or in com- 

 bination with either a concrete gutter or a concrete foundation. 

 When constructed alone they should have approximately the same 

 cross-sectional dimensions as stone curbs and should be constructed 

 in sections about 8 to 10 feet in length. Figures 2, 3, and 4 show the 

 three common types of concrete curbs. 



Vitrified clay curbing should be set in much the same manner as 

 that described for stone curbing. The principal additional require- 

 ment is that, since vitrified clay is a lighter material than stone and 

 the curb sections are ordinarily shorter, the bedding must be made 

 correspondingly more secure in order to prevent displacement. 



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Fig. 1. — Proper method of constructing stone curb. 



OPRRE 8S34 



Several sections of brick pavement in which curbs were altogether 

 omitted were constructed during 1915 in the State of Illinois. The 

 methods emploj^ed in constructing these pavements, which are desig- 

 nated " monolithic," are described on page 21. 



THE FOUNDATION OR BASE. 



A firm, unj'ielding foundation is one of the most essential features 

 of a brick pavement. This fact can be more readity appreciated 

 when it is considered that the surface of a brick pavement is made up 

 of small individual blocks, any one of which might be easily forced 

 down, causing unevenness in the surface, if the foundation were poor ; 

 and since the abilitj' of the pavement to resist wear depends very 

 largely on the smootliness of the surface, every reasonable precaution 

 should be taken to prevent any imevenness from developing. The 



