THE VALUE OF BITUMEN.

Hauraki Plains Gazette, Volume XXXVI, Issue 4870, 28 August 1925, Page 3

THE VALUE OF BITUMEN.

ANCIENT AND MODERN ROADS. PROGRESS THROUGH THE AGES, Almost as far back as our knowledge of ancient civilisation extends, authenic evidence exists that asphalt was known by the human race for its useful and valuable properties. Its earliest recorded use was by the Sumerians, a people inhabiting the Euphrates Valley prior to the lime of tlie Babylonians. Some of the oldest relics demonstrate that as > early as 3000 B.C. asphalt was used by. the Sumerians as a cementing medium for binding small objects or ornaments to sculpture, carvings’, and pottery. Asphalt was also used with clay to form a mastic which could be moulded into various forms. Such a mastic dating back to 2850 B.C. has been found. As early as 2500 B.C. the Egyptians used liquid or melted asphalt as a preservative coating for the cloth wrapping of mummies. Its water-proofing value was also known at this date, and there is good reason .to believe that the Ark built by Noah was treated with asphalt within and without for this purpose. As a mortar for brick, asphalt was evidently used in the construction of the Tower of Btibel, for the Book of Genesis states that “slime had they for mortar,” and the word “slime” is translated as “bitumen or asphalt” in the Vulagte. The same “slime” is also recorded as having been used to daub the basket of bulrushes in which Mc’scs was hidden in 1500 B.C. Nearly a thousand years elapsed before the use of asphalt; suggested itself for highway construction.. It was Nabopolassar, King of Babylon, who first used asphalt as a filler or mortar for brick pavements about the year 500 B.C. His son, Nebuchadnezzar, continued thiis practice by surfacing his father’s road,, as is proved by this inscription found on a brick taken from one of the streets: “Nebuchadnezzar, King of Babylon son of Nadopolassar, King pf Babylon. Tlie streets of Babylon, the procession streets of Nabu and Marduk, my lords, which the father who begot me hap made a road glistening with asphalt and burnt bricks. I, the wise suppliant, who fears their lordships, placed above (resurfaced) the bitumen and burnt bricks a mighty superstructure of shiny dust (metal chips) and made them-strong within with bitumen and burnt bricks as a highlying road. Nabu and Marduk, when you traverse thepe streets in joy may benefits for me rest upon your lips, life for distant days, and well-being for the body. Before you I will advance upon them. May I attain eternal age.” Thus, long before the birth of Christ the value of asphalt for binding, moulding, preserving, and waterproofing was reoegnised and utilised in and about the Mediterranean region. Asphalt Was also known and used in ancient times by the Incas of Peiu, who established a magnificent system of highways-. Early in the eighteenth century deposits of limestone were discovered in France, and in 1802 one of these deposits was exploited and the product marketed as a mastic for bridges., sidewalks, and floor-coverings. In 1838-a sidewalk of the old Merchants’ Exchange building at Philadelphia, United States of America, was laid down with asphalt. In 1854 the first asphalt pavement was laid in Paris in a rather crude manner, and this was followed in 1858 by the construcion of pavement more nearly represented by the present pratcice. In 1868 Threadneedle Street, London, was paved with asphalt.

These early experiments gave such promise of ultimate success that attempts were made to utilise asphalt proper in combination with sand and stone. At the present time asphalt is used more extensively than any other road-binding and waterproof material. It is used in various ways to suit the local conditions of its users. Thus, through the ages the cementing and waterproof qualities of bituminous asphalt have been realised, and at the present time these qualities render bitumen (which is the cementing agent in asphalt) the best material for permanent street and road construction.

APPLICATION TO NEW ZEALAND.

Almost every local body throughout the Dominion is faced with the problem of maintaining its waterbound macadam roads in a ; fit condition to carry modern traffic. The class of traffic has, changed, and the volume has increased so rapidly that the old methods of road construction are now hopelessly inadequate. Theie is no doubt that the old water-bound macadam roads in almost every locality are becoming worse year by year, in spite of the enormous amount of money spent in the attempt to keep them in fair order. As time goes on, and the volume of motor traffic increases and becomes faster and heavier, as it is bound to do with the better class of roads that are being laid down in all parts of the country, it will be necessary for every district to provide roads that will stand up to this class of traffic. Local body engineers arc well aware that the time is at hand to adopt more up-to-date methods than have sufficed in the past, and many experiments have been carried out with .a view to solving the road maintenance problem. Tar has been tried, and the old tarred roads have given good service in the past, but in spite of improved metohds of distillation and application it has become patent to the thinking engineer that tar and tar products as road binders have their limitations. The value of distilled tar for road-making depends entirely upon the percentage of bitumen it contains.

A number of theories have been advanced by noted scientists, on the origin of asphalt as it occurs in nature, and all these theories concur that in its production petroleum plays the parent part. In fact, the natural transformation of petroleum into aeplialt is to-day taking place in plain view in certain localities. A few

years ago one of the oil-producing companies in America had an ovei - production of petroleum form some of its large wells, and to save the material about 21 million gallons were impounded in a nearby valley. Three years later this petroleum lake had, through natural evaporation, been transformed into soft asphalt. With the growth pf the petroleum industry and the increasing demands for asphalt, refiners learned how to manufacture asphalt from asphaltic petroleum. In 190’2 about 21,000 tons of asphalt were produced from domestic petroleum; by 1912 the proproduction of eptroleum from some and by 1917 to 1,300,000 tons. Statistics prepared by an American good roads' association show that if the, paved streets of 290 American cities were merged into a. single highway 18ft wide, such a highway’would extend for ‘56,975 miles, or enough to mere than twice encircle the e'artn. Asphalt far outstrips all other paving types. The , 601,6'53,547 square yards of pavement in these 290 cities, which include all 1 but three of the cities of 100.000 of population and over, comprise the following, given in millions of square yards: Gravel t roads 48, water-bound macadam 84, bituminous macadam (penetration method) 32, asphalt concrete (hot mix method) 55, sheet asphalt (hot mix method) 164, asphalt blocks 6. brick 102, cement concrete 25, wood blocks 15, stone blocks 54, other types not described, asphaltic 7, non-asplialtic 6.