BRICK PAVEMENTS are composed of tough, hard, non-absorbent brick. designed to withstand the hammer-like blows and abrasive action of hoofs and wheels and to resist the action of water and frost. In size, shape, and general appearance they resemble ordinary building brick, but they are made and burned with more care. (See BRICK.) Where feasible, brick should have a concrete foundation. On tho lat ter a two-inch eushion of sand is laid. The bricks are set edgewise on the sand, their lengths run ning across the' street and joints being broken. At street intersections each quarter of the area is laid diagonally, so the length of the brick will be at right angles to the direction of the traffic, when the latter is turning corners. The bricks are rammed to bed them firmly. Such bricks as sink below the surface' are replaced with deeper ones. Although the bricks are set in as close contact with each other as is feasible, open spaces remain. Nearly all the fillers described above have been used for brick pavements. Sand is not suitable, as it quickly washes out. There is great difference of opinion as to the relative merits of Portland cement grout and the bitu minous fillers. Both kinds of filler arc poured over the surface of the pavement and swept into the joints with brooms. After this has been done the pavement is covered with a thin layer of sand. Expansion joints are sometimes pro vided, both lengthwise and crosswise' the streets, the former at each curb line, and the latter at intervals of 25 to 50 feet. They are made by filling a narrow space or spaces between bricks with some form of bituminous cement.
Woon PAVEMENTS are composed of blocks of wood, either round or rectangular, laid with the grain or fibre perpendicular to the foundation. The rectangular blocks are most commonly 3 X 9 inches X 4 to 6 inches deep. The round blocks are 4 to S inches in diameter. and about 6 inches deep. Blocks of hexagonal and other special shapes have been tried, but experience has shown that the special forms have no ad vantage commensurate with their cost. The round and the rectangular blocks are sawed to the desired lengths from logs or from plank, respectively, gang saws sometimes being used. The bark, and in some cases the sop-wood, is cut from the round blocks by machinery. The blocks are sometimes treated chemically with creosote or some other wood preservative. Unless this is done it is questionable whether wood should be used for paving purposes. The round blocks necessarily have large spaces be tween them to be filled; the rectangular blocks are sometimes laid close together and sometimes with spaces. Various fillers are used. Expan
sion joints are often, but not always, inserted at the curb, of sand, and covered with bitu minous cement or other materials. Probably round cedar blocks have been more freely used in America than any other wood. In Europe pMe, fir, and more recently Australian hard woods, known as Karri and Jarrah, have been employed. For the best results, wood should be laid on a concrete foundation, but this has sel dom been done in the United States. ln Chi cago round cedar blocks are laid as follows: Not less than two inches of sand is spread over the surface to be paved. On this a flooring of two-inch hemlock plank is laid, supported also at the centre and each end by 1 X 8-inch boards, laid tlatwise in the sand. The blocks arc set on end on the plank. The spaces between the blocks must be at least three-quarters of an inch, but not more than one and one-half inches in size. The joints are filled with clean, screened dry gravel, thoroughly rammed in, after which the whole pavement is covered with hot coal-tar pitch, and this in turn is covered with three quarters of an inch of roofing gravel. At In dianapolis rectangular red cedar blocks were laid in 1894 and 1896, and heart-wood Southern yellow pine later on. The first blocks were not treated, but the later ones Were creosoted. The blocks were laid on a concrete foundation, with a one-inch sand cushion, and latterly with expansion joints at the curb. The joints were partially filled with fine sand, after which the pavement was rolled, then covered with hot pav ing pitch and fine gravel. The cedar blocks were five inches. and the pine blocks four inches deep. Since 1900 creosoted wood blocks have been gaining in favor in the United States. , Some of the London hard-wood pavements have been of blocks 3 X 9 X 5 inches deep, laid close. At the gutters three courses were laid parallel to the curbs, the blocks having been dipped in a boiling mixture of four parts of tar and one part of pitch, and there being a one-inch sand filled expansion joint at each curb. The main part of the street was covered with blocks laid crosswise. The filling is effettcd with boil ing tar and pitch, first covering the entire sur face, then worked into the joints; after which cement grout is floated over the pavement, then sand thrown over all. Soft-wood pavements of the same period in London were not less than six inches deep, creosoted, and had their joints filled with a grout of blue has lime and sand.