Macadamising is a form of road surfacing introduced to Britain by John McAdam, in 1816. The process involves covering the road surface with small, broken stones, so as to form a smooth, hard, convex surface - the surface being convex so as to allow water to run off to the sides. Today the stones are mixed with molten asphalt and compressed by a roller. Research Macadamising
Macadamising was a system of road-making invented by John Macadam in 1819 involving the use of stones broken to six ounces weight and the use of clean flints and granite chippings. Research Macadamising
Slag is the chemical compound resulting during the smelting of metallic ores. It results because of the action of the flux on impurities in the ore. Slag generally consists of silicates, formed by the combination of silica with alumina, lime, magnesia, oxides of iron or other metals. By the formation of slag, the impurities in the ore are removed, and if the metallic contents of the slag are of no value the slag is regarded as smelters' refuse. Some slags, however, consisting mainly of metallic oxides produced during the refining processes, are resmelted and such slags are termed cinder or scoria. As slag has to be separated from the valuable metallic material, its fluidity, at the smelting temperature, is an important factor, and some substances such as an oxide of zinc are apt to make slags pasty.
Slags vary in chemical composition, but those which crystallise are regarded as definite chemical compounds. The colour of slags affords n indication of the composition, for example green denotes the presence of iron and copper oxide produces a red slag. Slags are used for various purposes, as ballast for railways, macadamising roads, making into bricks and others. Some slags may be burnt with lime, thus making an efficient hydraulic cement, and slag from the basic Bessemer process forms a fertiliser containing phosphorus. Research Slag
Basalt is an igneous rock, consisting of augite and triclinicfeldspar, with grains of magnetic or titanic iron, and also bottle-green particles of olivine frequently disseminated. It is usually of a greenish black colour, or of some dull brown shade, or black. It constitutes immense beds in some regions, and also occurs in veins or dikes cutting through other rocks. It has often a prismatic structure as at the Giant's Causeway, in Ireland, where the columns are as regular as if the work of art. It is a very tough and heavy rock, and is one of the best materials for macadamising roads. Research Basalt
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Macadamising
