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Outdoor Problems of the Householder: Clay
Sand Clay and Burnt Clay Roads. -While pure sand or pure clay are extreme types of bad roads, a proper combination of the two materials makes a type of road surface almost equal to macadam. Natural sand and clay roads are sometimes found. But more often there is a deficiency of either sand or clay. One or the other must then be supplied to produce a satisfactory surface. Clays vary in binding power between two extreme types. One kind is very "plastic" or sticky when wet. This is called "ball clay" because a lump of it placed in water will keep its shape. The opposite type is less sticky but will readily crumble when wet. Ball clay is somewhat more difficult to handle but makes a better road because it has more binding power. Some clays contain more or less sand, loam, or other constituents.
Hence the method of road making varies somewhat according to the available materials. It is a good plan to experiment with clays from different beds and choose those which give the best results, even if they must be hauled greater distances.
The ideal combination of sand and clay is in proportion such that the voids or spaces between the grains of sand are just filled with the finer clay particles. Any excess of clay defeats the object of the mixture by enabling the particles of sand to slip loosely over one another.
To test the soil and ascertain the exact proportion of clay required, fill one of two glass tumblers level full of an average sample of sand from the roadbed and the other level full of water. Now gently pour enough of the water over the sand to fill the voids between the particles of sand up to the brim of the glass.
Measure the quantity of water remaining. The proportion taken up by the sand to the quantity remaining will show the proportion of clay which will make an ideal combination.
In practice, the mixture of sand and clay should be about four or five inches in depth. Thus by measurements of the road surface to be covered, the quantity of material required can be readily estimated. But somewhat larger proportions of sand or clay will usually have to be added from time to time to take the place of that lost by washing and to mix with clay brought up from below in the process of road making, or by traffic.
To Make a Sand Clay Road Over a Sandy Sub-soil. - First provide proper drainage. Then crown the roadbed slightly beginning nearest the source of clay. Now dump the Cross section of road, showing clay cover on "deep" sand sub-soil. (Wm.
L. Spoon.) first load of clay at the point nearest the clay bed and spread it out evenly before driving over it. Finally crown the clay to a depth of six or eight inches in the middle of a twelve-foot road and taper to a thin edge at each side. Cover to the required depth with a layer of clean sand. If the clay tends to crumble when wet it may not require any further treatment, except to add more sand from time to time to keep the surface smooth and prevent the formation of mud. But if it is of a plastic and lumpy character it will be necessary to plow or harrow it by turns to break up the lumps and thoroughly mix the clay and sand together. Choose for this purpose a time when the road has been thoroughly wet by heavy rains and turn the surface to a depth of about four or five inches with the plow. Follow with a cutaway or disc harrow. This is a hard job since the clay forms a thick, pasty mud. But if properly done, it produces a surface which will stand traffic almost as well as first class macadam and at about one-sixth the cost.
The best clays for road making are usually red or mottled red and white. If such can be found it will pay to haul them considerable distances.
To Construct a Sand Clay Road Upon a Clay Sub-soil. -Take special care to provide proper drainage.
Crown the clay at the rate of at least one-half inch per foot. Now turn over the surface to a depth of at least four inches with the plow and thoroughly pulverize with the harrow. Choose for this purpose a time when OUTDOOR PROBLEMS OF THE HOUSEHOLDER 297 the road is comparatively dry. Apply clean sharp sand to a depth of six to eight inches in the middle of the road and slope at the rate of onehalf inch per foot, toward each side. Mix with the plow and harrow. Finish he road by puddling with the hari W after a rain. Apply more sand to the surface from time to keep it smooth and prevent its becoming sticky.
To maintain a sand clay road, shape the surface with the scraper while wet and soft, but defer rolling until it has been thoroughly puddled by reans of the harrow or by traffic.
A sand clay road is not finished until a proper combination of the sand and clay has been effected under the influence of care and traffic, however long this may require. Hence, the cost of maintenance during the early stages may be properly included in the cost of construction. But when a proper combination is effected, the surface will be found practically as hard and durable as macadam. The total cost will be much less, usually at the rate of about $600.00 a mile.
Burnt Clay Roads. - Where sand is not available, clay roads may be improved by burning or "clinkering" the clay to destroy its plasticity or sticky quality. Instructions for this process will be furnished by the Office of Public Roads connected with the Department of Agriculture at Washington, D. C., on request.
The Split Log Drag.--The best and cheapest means of maintaining all kinds of earth roads is the use of the split log drag. The average annual cost of maintenance of earth roads by other methods is from forty to fifty dollars a mile. Whereas earth roads can be kept in first class condition under ordinary circumstances with the split log drag at from two to five dollars a mile. The cost of such a drag is nominal. There is no reason why any householder, who owns a team and has private roads to maintain upon his own lands, should not have a drag of his own. Incidentally, he can work the public road in front of his own premises, both with an eye to his own convenience and as an object lesson to others.