Author: International Schools

Publisher: Rarebooksclub.com

Published: 2013-09

Total Pages: 122

ISBN-13: 9781230079431

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 edition. Excerpt: ...quartz pebbles is of very little value as a road material. These pebbles are very smooth and possess scarcely any binding power; where they constitute more than half the mass, the gravel is usually worthless as a covering material for roads, unless mixed with some binding material. Between these two extremes, that is, between the undecayed trap pebbles, which are the best, and the white quartz pebbles, which have the least value, are the pebbles of syenite, granite, chert, limestone, and mica-schist, occurring in great variety and widely differing quality, but all possessing more or less value as road material. Much the same qualities are desirable for gravel as a road material as those that have been noticed for broken stone. The gravel for road material should be sharp and comparatively clean; it should be screened before being spread upon the roadway, in order to separate from it the excessively large pebbles and also the injuriously fine and loamy material. If found mingled with a large proportion of clay, it will be worth while to wash it. Gravel for road material should not contain more than one-fourth part sand or clay, and not more than one-half of its pebbles should be composed of white quartz. Gravel composed of stones of angular form, such as is taken from pits, is much better for road purposes than that composed of round or oval pebbles, such as is commonly found in the beds of streams. Where the gravel is composed largely of white quartz, round smooth pebbles, or any material having small cementing capacity, a binding material should be added. Probably the best available material for this purpose is the ordinary red or brown iron ore found in nearly all parts of the country. It is very common in swamps, and is valuable for...