OILED ROADS.

Hauraki Plains Gazette, Volume XXXIX, Issue 5303, 23 July 1928, Page 2

OILED ROADS.

AN AMERICAN PROCESS.

EXPERIMENTS ON PUMICE.

The Main Highways Board, proposes to treat, a section of the RotoruaTaupo road! with a binding oil of an asphalting nature. An. experimental section near Ta,upo has proved satisfactory, and since the cost, of carting metal to this locality is prohibitive, . oiled pumice surfaces are' likely to find favour. The Cost of treating pumice surfaces is between £l2OO and £l4OO a mile, so that very good results under hea,vy traffic will have to be assured before s.uch expensive! work can be undertaken to any extent. Oil treatments for earth or sand: roads are popular ip the United States. These surfaces have) simply been given two coats of asphaltic base petroleum or, petroleum residuum, and have successfully carried heavy traffic. Where the ground seems to be more or. less of a gravelly nature the oiled road has proved particularly successful a,s a cheap expedient This is probably due to the fact, that such soils have excellent natural drainage. The roadway is first shaped, dampened, and rolled with a, IMon. roller until the surface is unyielding. The surface is then loosenied anjet pulverised with a cultivator and harrow to' a depth of 4in, and again watered tomake; it roll satisfactorily. All stones, over 3in in diameter are removed or broken up. After further rolling: with the 10-ton roller, minor dieprfessions are filled up and the road again dampened, an.d finished off with a; 5ton rolled; Oil at a temperature of between 300 deg. and 400 deg. F. is applied with pressure destributing sprays at a rate of five-eighths U.S. gallon per square yard, and left for at least 12 hours, when a layer of %in to %in screenings sufficient to absorb all the surplus oil is evenly spread. A second coating of oil at the rate of three-eighths U.S. gallon pen square yard is then, applied, and afte® a brief lapse of 12 hours, a layer, or* 5

'•-somewhat finer screenings is spread, any surplus stone being r.aked or swept off. The. surface is then given a final rolling until it is uniformly smooth. Any sticky places are to be treated with further screenings, as necessary.

This type of trea.tm'ent is quite commonly used for the first surface on new roads jn suburban subdivisions in California, it deals effectively with the dust problem, and is very suitable for a dry climate.