. Agricultural engineering; a text book for students of secondary schools of agriculture, colleges offering a general course in the subject and the general reader. Agricultural engineering. 156 AGRICULTURAL ENGINEERING extent in the gravel. On the other hand, it has some undesirable characteristics. It loses its binding power when dry, and is susceptible to the action of frost. In many cases other kinds of binders are used. Stone dust has excellent cementing properties and is considered better than clay, but is more expensive. As will be explained in the chapter on stone roads, automobiles hav
. Agricultural engineering; a text book for students of secondary schools of agriculture, colleges offering a general course in the subject and the general reader. Agricultural engineering. 156 AGRICULTURAL ENGINEERING extent in the gravel. On the other hand, it has some undesirable characteristics. It loses its binding power when dry, and is susceptible to the action of frost. In many cases other kinds of binders are used. Stone dust has excellent cementing properties and is considered better than clay, but is more expensive. As will be explained in the chapter on stone roads, automobiles have introduced many new problems in connection with road construction. Many forms of binders and dust preventives are being experi- mented with. Bitumen, tar, crude oils, and chlorides are used to hold the gravel together. Drainage. A good gravel road must be thoroughly underdrained if it is to be satisfactory. The method of draining does not differ materially from that described for earth roads. Many mistakes have been made by those. Fiqst Class Oeciioi in Cut Fig. 82. Cross section of gravel road. (Iowa Highway Commission.) having the matter of road construction in hand, by applying surfacing material to a road which needed under drainage badly, and so the material did not produce the results which were hoped for. The ground water coming up from below softened the surface, and the gravel was forced down into the earth until it entirely disappeared. Gravel roads should have sufficient amount of crown or lateral slope to secure the rapid drainage of all surface water to the side ditches. The amount of slope is usually given as 3^ to 1 inch to one foot of width. Surface Construction. There are two general methods of surfacing roads with gravel. The cheapest method is known. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the origi
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagricul, bookyear1919
