ROAD-MAKING METHODS

Northern Advocate, 15 September 1932, Page 8

ROAD-MAKING METHODS

IMPORTANT EXPERIMENT. HEAT TREATMENT OF SOILS. SYDNEY, September U. An experiment of great interest and importance to shire and municipal councils in sparsely-settled parts- of Australia, where there is difficulty in securing suitable material for road making, was carried out in .Sydney this week, and next month will be tried in Queensland under practical road construction conditions. The experiments follow a paper read last year before the Sydney branch of the Australian Institution of Engineers, by Air. L. R. H. Irvine, who explained the result of experiments he had made in heating soil, such as that composing the surface of country roads, in a manner that converted it into hard, stono-like material. Mr. Irvine claimed that ho had experimented with fifty soils. collected from roads in different parts of New South Wales, and had found that most of them were capable of being economically converted into road-making material of a hard and durable nature.

Mr. Irvine explained that the hard ening effect of the super-heat on the soil was due to the melting of fusible constituents present in nearly all soils. The process of hardening was fundamentally the same as that of brickmaking. Fusible constituents in the road soil of a collodial character, when melted, formed a flux which ran between the coarser particles and cemented the whole into a semivitrified mass. The claim is that the material so made can either be used for forming a hard, brickdike surface on the road, or that it can bo used for making cement concrete either for roadmaking or bridge construction. Many road construction engineers, who studied the data supplied by Mr. Irvine, expressed conviction that the principle was good, and capable of being put to practical use in rural parts. One of the strongest supporters was Mr. .1, R. Kemp, Queensland Commissioner for Main Roads, who asked Mr; Irvine to have a machine constructed, to treat soils in the manner recommended, and promised to have it thoroughly tested on a length of road in Queensland. Mr. Irvine has had the machine built by a Sydney engineering firm, and it was tested during the last two days with ordinary black soil. The product was a black, concrete-like rrui.terial, which was as hard to break with a hammer as basalt. The machine is designed to treat at one time a. length of road 12 feet by fi feet, but could be extended to a width of 8 foot. It is mounted on wheels so that when one section is ‘‘cooked,” it can be moved to the next twelve feet. Wood can be used for fuel to provide heat in a gaseous form, and there would, be no expense in bringing coal or oil long distances.

Members of the engineering staff of the Main Roads Board, and other road engineers, witnessed the experiments and considered they .-justified the claim made by Mr, Irvine. Regret was expressed that the machine was not to be tried out experimentally in New South Wales rather than in Queensland. Mr. Irvine stated that Queensland had the first claim, as it was owing to the direct encouragement given by Mr. Kemp that lie had had the machine constructed on a scale sufficiently large to give practical tests. The test is to be made on a section of the road from Brisbane to Ipswich. The heat treatment can be so arranged that a road surface can be “cooked” to adepth of from 2 inches to 6 inches according to the class of traffic that it has to carry. Mr. Irvine stated yesterday that should there be any desire to have a practical test on a rural road in New South Wales, he could have another machine built-in Sydney similar to the one being sent to Queensland.