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116 ANNUAL REPORT 
the walk had been constructed as the better class of walks is today, it 
would have remained in perfect condition. It seems almost incredible 
to believe that people can go on year after year stumbling over miserably 
irregular brick walks, when smooth, regular concrete walks are obtainable. 
Figure 60, page 112, shows a section of a concrete walk. Figure 61 
shows a well preserved old concrete walk. 
CURBS AND GUTTERS. 
A much later application of concrete than that of sidewalk construc- 
tion is its use for curbs and gutters. So many of the natural stones when 
used for curbs absorb water and disintegrate under frost action. Lime- 
stone is especially subject to disintegration because of its lamination. 
Sandstone wears rapidly at points where wheels rub. In some parts of 
our country neither limestone nor sandstone can be obtained at a reasonable 
price, thus the demand for some good substitute has arisen. 
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Section of Gombined Goncrele Gurb %« Guller 
Figure 62. 
It has been found very easy to put in the plain concrete curb, and it has 
proved very durable and at the same time has added much to the appearance 
of the street. Another problem that the road engineers have had to solve is 
the building of a gutter that will be smooth enough not to retard the flow 
of storm water upon very flat grades and at the same time so impervious, 
durable and tough that it will not rot out under continued dampness nor 
wear out quickly under usage. Cobblestone, brick and stone block retard 
the flow of water. Asphalt and coal tar rot or disintegrate under the 
action of water. Concrete once more fulfills all the-requirements. By 
combining the curb and gutter into one monolithic whole, several diffi- 
culties are avoided. The displacement of the curb, due to frost upon one 
side or the expansion of the street upon the other, is greatly reduced. 
Shrinkage and expansion do not cause cracks along the face of the curb, 
