HARDENING THE SURFACE - SAND ROADS. The great disadvantage of pure sand as a road material is the freedom with which the grains move one on the other; and therefore to improve a sand road grass should be encouraged to occupy all the space possible, since its roots will decrease the movement of the grains under the tread of the hoofs and wheels. It is an advantage if low growing bushy vege tation occupies the surface clear up to the traveled way—both for the shade and for the binding effect of the roots and the leaves. The leaves fall into the ruts and also aid in binding the sand.
Where no other recourse is possible, it is advantageous to have two roadways adjacent to each other, one of which is planted with grass while the other is in use. If the traffic is not very great the • effect of the grass will last for a year or two after the road is again used by the wheels. A fertilizer is sometimes applied to stimulate a growth of grass upon the wheelway. In some localities the sand i3 so fine that it drifts like snow, and fills the partially hardened way, in which case the road is improved by planting the roadsides with grass to prevent the sand from blowing.
A road on pure sand is improved temporarily by covering it with a thin layer of any vegetable fiber, as decaying leaves, straw, marsh hay, waste from sorghum mills (begasse), fibrous or string like shavings, etc. This fibrous material soon becomes incorporated with the sand and decreases its mobility; but the vegetable matter wears out and decays, and consequently the effect is only temporary.
The length of time such expedients will last depends upon the climate and the amount of travel. Sand roads improved with three to four inches of shredded wood (excelsior) have kept in reasonably good condition for a year or two.
The only permanent improvement possible for a sand road, aside from substituting an entirely new wearing surface, is to add a thin layer of tough clay, and incorporate it with the sand—either by traffic or with a harrow or a corn cultivator. This is expensive at best, and it is difficult to get the sand and clay thoroughly incor porated in the right proportions; but the result is permanent.
In this connection it is a significant fact that the sand shoulders of a broken-stone road soon become firm and hard, owing to the infiltration of the fine dirt and stone dust washed from the sur face of the roadway. The fine particles of dust between the grains of sand act mechanically to decrease the mobility of the sand, and also increase capillary attraction and diminish percolation, which in turn also keeps the sand damp and still further decreases its mobility. Apparently, then, the incorporation of fine dust in a sand road would improve it; but it would be difficult to procure sufficient dust for this purpose.