Road materials and quarrying

Abstract

1. Introduction Insofar as quarrying has any public image it tends to be associated with the Dartmoor concept of a criminal swinging a 14 pound sledge-hammer; there is in southeast England the other image of rapacious gravel scratchers digging up people's gardens when they're not looking. Because of this general lack of understanding it is perhaps useful in a paper of this kind to define quarrying in more scientific and precise terms. In the Institute of Quarrying it is defined briefly as the extraction of surface minerals and their processing for the market. Thus although the popular concept of breaking ground is correct, it is only half the story. For by far the most complex and technical side of the industry is the preparation of end products for distribution. Moreover, a wide variety of materials is involved, including the range of igneous rocks, limestone, chalk, sandstone and sand and gravel, the latter including sea-dredged material. From these are produced the end products, ranging from fill as the most unsophisticated, through lean-mix and cement stabilized bases, to tar- and bitumen-bound base courses and asphalt wearing courses; also concrete for rigid pavements and for structures ancillary to the road itself. It is important to realise that, in this country, the quarrying industry itself produces and distributes these end products. Indeed so complete is the vertical integration in some cases that a company may also lay the end products and complete the operation. Thus the industry is a very close partner in road