123. Pavements being so nearly related to the masonry work of a building, and usually specified in a mason's contract, are discussed at this point.

124. Pavements may be made of thin slabs of stone, called flags, with a concrete base and Portland cement on top for a finish, or of very hard bricks known as paving brick.

In localities where large stone flagging is cheap and plentiful, it makes probably the most economical pavement, and is about as satisfactory as any, though a smooth and exceedingly durable pavement can be made with concrete and cement. But should it ever be necessary to cut through the pavement or change the grade, the cement and concrete must be destroyed, while stone flagging, on the contrary, can be taken up and relaid either in the same place or used elsewhere. It is also easier to repair a stone pavement than any other kind.

125. Stone pavements should be built of a kind of stone that will split with comparatively smooth and even surface, as when the surface of the stone requires dressing the pave will be more expensive than when concrete and cement or paving brick are used. Stone pavements for yards and the flagging of areas should be from 2 1/2 to 3 inches thick, with the edges trimmed smooth, so that the stone will be rectangular and the joints straight. The flags should be laid on a 2-inch bed of sand, and for good work the edges should be bedded in cement, as shown at b in Fig. 49, where a shows the stone flagging, b the cement joint, and c the sand bed. The cement should run 3 or 4 inches under the stone, and the joints in the pavement should be well filled with cement mortar, made of 1 part cement to 1 part sand.

Pavements And Sidewalks 51

Fig. 49.

126. Stone sidewalks are laid in much the same manner, but should consist of stones 5 feet long and 3 inches thick; or, if they are 8 feet long or more in length, they should be 5 or 6 inches thick. It is best to lay sidewalks in one course from curb to fence line, unless they are exceptionally wide.

In most of the Northern and Western states, the stones, if laid only on a bed of sand, will be affected by the frost, and become displaced and out of level in two or three years. Flagstones, therefore, especially on business streets, should have a solid support at each end. Fig. 50 shows the proper method of laying a pavement so that it will not be affected by frost. A 12-inch dwarf wall should be built at the curb line, as shown at a, and carried below the frost line. The curbstone b is from 4 to 6 inches thick, and rabbeted into the dwarf wall; c shows the gutter, and d the stone pavement, supported at its center by a small wall e. If the sidewalk is laid in two courses, or if it extends to the building line, it may rest upon a break in the foundation wall /, as shown.

Pavements And Sidewalks 52

Fig. 50.

127. Cement sidewalks should be laid as follows: The ground should be leveled off about 10 inches below the finished grade of the walk, and well settled by ramming. A foundation 5 inches thick should then be laid, of either coarse gravel, stone chips, sand, or coal ashes, well tamped, or rolled with a heavy roller. The concrete should then be prepared in the proportion of 1 part of cement, 2 parts of sand, and 3 parts of gravel, mixed dry; then a sufficient quantity of water is added to make a stiff mortar. This concrete should be spread in a layer from 3 to 4 inches thick, and should be well tamped. Before the concrete has set, the top or finishing coat should be laid, and only as much concrete should be used as can be covered with cement on the same day, for if the concrete gets dry on top, the finishing coat will not adhere to it. The top coat should be prepared by mixing 1 part of the best Portland cement, and 1 part of fine sand or 1 part clean, sharp, crushed granite or flint rock. The materials should be thoroughly mixed dry, and water then added to give the consistency of plastic mortar. It should be applied with a trowel, to the thickness of 1 inch, and carefully smoothed and leveled on top between straightedges laid as guides. Used in the above proportion, 1 barrel of Portland cement will cover about 30 square feet of pavement. Fig. 51 shows a section of a concrete pavement; a shows the ashes or spalls; b, the second coat of cement and gravel or stone; c, the finishing coat of Portland cement; d, the street having; e, the building line; and f, the soil.

Pavements And Sidewalks 53

Fig. 51.

128. Brick sidewalks should be laid with good, hard, paving brick, sound and square, laid flat, herring-bone fashion, on a bed of sand from 4 to 6 inches thick. After the bricks are laid and graded (which should be about 1 inch to 10 feet, to drain the water to the gutter), the entire surface must be covered with sand, which must be swept over the bricks until the joints are thoroughly filled. If extra thickness of wearing surface is desired, the bricks may be set on edge, and covered with sand as above described.