CONSTRUCTION NOTES 273 



the ground water drains naturally, such provision as previously outlined is 

 not necessary. Neither is it necessary to take such extreme precautions to 

 provide adequate drainage, even when roads are constructed in a clay soil, 

 under climatic conditions where frost action is not an important factor. 



IV. Curbs. Curbs may be constructed either of stone (Plate 113, 

 figure 4) or of concrete (Plate 114, figure 2). In each instance where the 

 road surface may be paved with brick, provision should be made for an 

 expansion joint from one-half to one inch in width (varying with the width 

 of pavement) and filled with some tar or asphalt preparation. The lines 

 and grades for any curb should be carefully established and checked before 

 any forms are put in place. It is expensive to make changes after the con- 

 crete has once been poured. For the construction of concrete curbs (Plate 

 114, figure 2) a trench is excavated approximating 16 inches in width and 

 three feet in depth. The average depth of the concrete curb is between 18 

 and 20 inches. The tile drainage is installed and the cinder fill put in place 

 and thoroughly tamped so that the surface of the cinders is approximately 

 1 8 inches below the proposed finished grade for the top of the concrete curb. 



Forms are then constructed of material sufficiently strong to hold 

 their position and shape under the weight of the concrete. The mixture of 

 concrete, consisting usually of one part cement and two and one-half parts 

 sand and five parts stone or gravel, is put into place and thoroughly tamped. 

 Metal corners to protect the curb from breakage by vehicles are often used 

 in public work, but s-eldom on private places. The finished surface of the 

 curb may be obtained by the use of a smooth form, by applying a coat of 

 cement mortar after removing the form, by tooling the surface after it has 

 thoroughly set, or sometimes by brushing the surface before it has entirely 

 set. It is very desirable to leave joints in the concrete curbs, at intervals 

 of approximately six feet, of which every fourth or fifth should be an expan- 

 sion joint. The finished surface of any concrete curbs or gutters should be 

 sprinkled with water two or three times daily for a period approximating 

 one week during hot or dry clear weather. During cold freezing weather 

 the surface should be covered with hay, straw or manure for about ten days 

 as a protection against freezing. 



Stone curbs are of the approximate dimensions shown in Plate 113, 

 figure 4, and are installed upon a well-drained foundation of thoroughly 

 compacted cinders. It is very necessary that the cinders and loam fill at 

 the back of the stone curb should be thoroughly tamped before any gutter 

 or road metal is constructed. 



Combination curbs and gutters (Plate 114, figures 4 and 40) are 

 constructed upon a firm foundation of cinders. It is preferable to con- 

 struct the desired type of forms on the proper lines and grades and to pour 



