Arizona republican., 1916-12-10
Improving Earth Roads By Oiling

T By The Iowa State Highway Commission

All experiment indicates that oil treatment, if properly applied upon a well graded roadbed in proper condi- ton for it. and subject to compar- atively light traffic, is splendid. through more or less temporary. dust and mud preventive. Every eXperi- mcnt tried so far m Iowa indicates that there must be at least one ap- plratfon each year, and sometimes two each year, to produce the desired results. oil does not add much to the resistance Of q dirt road to wear. Heavy traffic on dirt road will tear aTart the particles of earth but the oil- soaked condition prevents the part iclos from rising in dust clouds There will he a mat of dust on the surface of the oiled road. though not so much aS on an unoileG road. but the dust win generally cling to the road.
 As 8 lust preventive, the oil works finely through short storms such as prevail during the greater part of the year The hardest trial of the roads come during the spring hreakup Their ability tO resist destruction at this .ime depends on the amount of traffic horne and the general drainage conditions of each road. If water stands in the side ditches. the road will become saturated. and the alter nate freezing and thawing will add to the difficulties the oil has to over come If the road surface is rough or rutted or has holes in 1t where water may stand, the difficulties will be increased. lf the ruts or holes ex- tend through the oiled crust, the water has free access to the dirt be- low and can soften it.
 Water below the oiled crust. which has soaked down through the surface , Of the road or percolated sideways from the ditches helps to reduce the good effect of the oil. If the road while in this condition is much used
 mud is sure to result. The oil-treateC dirt of the top surface k mixed witt the lower dirt. When the road dries the surface is no longer exclusively uil-trcated earth. but has a large pro- portion of untreated earth in its make up. Onlv another application of oi ran restore the road 10 it's origina oiled condition.
 on the whole. the experiments ir road oiling this season have giver better results than those of last year This has been due to three things mainly. a better grade of oil. bettel preparation of the road surface be l fore oilnc. and more careful appli- | cation )f the oil.
 l In the earlier work the tendancA i was to use petroleum residRum iron i the different oil fields without rcgar, 10 it's suitability for this particular work. Much of this oil possessed ; i greasy characteristic. indicating a laci Of binding value and durability. Tho 1 samples received by our laboratory
 in 1916 have generally had much less 1 of this greasr characteristic. Thes' ] tests have shown that the body of th'
 oil was a durable asphaltie materia : possessing good binding properties ! There has also been tendency t' 1 Use heavier grades of oil than hereto
 fore and this Is undoubtedly an ad
 vantage if not carried too far.
 1 The work this year indicates con ! clasiyelr the desirabilitv Of applyins , tho oil hot because of It's bette penetration into the road surface. Thi does not near that cold application , is likely to be failure. but .t doe mean that eaought better results an obtained bv the hot application t warrant the extra trouble and eXpens' l There are several methods of heat ing the oil before it's application L
 the road surface. The oil tx usuall
 shipped in cars equipped with stean
 coils. SO that the tank can he connect
 ed to a steam power plant and heate
 by means of the coils has been used
 and the coils are supplied with stean from The tractor which hauls it. Ii