CHAPTER VI.

BRICK PAVEMENTS.

304. BRICK, although one of the oldest materials used for paving, was not employed for this purpose in the United States until about twenty years ago. The first brick pavement laid in the United States was in Charleston, W. Va., in 1872. Since then the use of brick as a paving material has extended over a wide section of country; and in localities with moderate traffic such pavements appear to give satisfaction.

305. The advantages of brick pavements may be stated as follows:

(1) Ease of traction.

(2) Good foothold for horses.

(3) Not disagreeably noisy.

(4) Yields but little dust and mud.

(5) Adapted to all grades.

(6) Easily repaired.

(7) Easily cleaned.

(8) But slightly absorbent.

(9) Pleasing to the eye.

(10) Expeditiously laid.

(11) Durable under moderate traffic.

Brick pavements will be found in many localities to be superior to wood or broken stone, and in many cities and towns will be found superior to stone blocks.

306. The Defects of Brick Pavements.-The principal defects of brick pavements arise from lack of uniformity in the quality of the bricks and the liability of incorporating in the pavement bricks of too soft or porous structure, which crumble under the action of traffic or frost.

The employment of unsuitable brick is liable to be fostered by a popular desire to help a local industry without due regard to the

quality of the local clays for the manufacture of good paving brick. This circumstance, together with the comparative ease with which contractors who have little experience can bid on this class of work, and the difficulty of rejecting the lowest bid by local authorities, will in many places result in the failure of the brick pavements. If cities, however, in making contracts for brick pavements, will keep these contingencies in mind, and as far as possible exercise discrimination in selecting bricks made especially for this purpose and contractors interested in making these pavements popular, then the development of a great industry may be anticipated.

307. Durability.-Brick has been used for upwards of a hundred years in the Netherlands, and pavements laid half a century ago are still in good condition. There are several brick pavements in the United States from ten to eighteen years old which are still in good condition.

308. The general experience with pavements formed of suitable brick, laid on an unyielding foundation, with the joints filled with bituminous or Portland-cement grout, is that they furnish a smooth and durable surface, well adapted to moderate traffic.

309. Failures of the earlier pavements are frequently reported. These pavements were generally constructed on defective foundations, and with the ordinary building bricks of the locality. Such failures are the result of overhaste in the selection of the material, and poor foundations.

310. The durability of the bricks seems to depend (1) on the clay from which they are made being practically free from lime; (2) on the thorough grinding and mixing of the clay, so as to have no lumps in the bricks; (3) upon the bricks being thoroughly annealed.

311. The brick pavements at The Hague, Holland, are made of a hard-burned brick 8.668 inches by 4.33 inches wide and 2.16 inches thick. They are laid on a sand foundation 7.88 inches deep, with very little clay. Joints are laid as close as possible.

The Hague is a city of residences, and street traffic is very light. Amsterdam is paved almost entirely with brick. The road from Utrecht to Connighem, twenty-seven miles, is paved with brick.

312. Bricks are successfully used in Rotterdam, which is a commercial city. Two classes of brick are used-one made from local clays, and the other a scoria brick, manufactured by the Tees Scoria

Brick Company, of England. The local bricks are preferred for light traffic, and for medium traffic the scoria bricks.

313. Size and Shape of Bricks.-Bricks are passing through an ordeal similar to that through which wood for paving passed many years ago, with practically the same results, viz., that with a proper foundation neither odd shapes, grooves, lugs, nor other devices are necessary or beneficial. Experience shows that the most economical and desirable size for paving bricks is that of the standard building brick. Bricks of this size can be made more cheaply, burned more uniformly, and those which are unsuitable for paving can be utilized for building purposes, which would be impracticable with odd shapes. The imperfect ones of said shapes or peculiar form are so much waste material, and the cost of their manufacture must be added to the price of the good ones in order to protect the manufacturer from loss. Moreover, with irregular sizes and odd shapes it would be necessary for the towns employing brick pavements to keep a large stock of the different bricks on hand to make repairs, which would be expensive and troublesome.

314. Quality of Bricks.-The qualities essential to a good paving brick are the same as for any other paving material, viz., hardness, toughness, and ability to resist the disintegrating effects of water and frost. As with other materials, porous brick are unfit for paving.

These qualities are not obtained, as is commonly supposed, by vitrifying the bricks: in fact the application of the term vitrified to paving bricks is a misnomer. The process of vitrification is to convert into glass by fusion or the action of heat. Glass is a smooth, impermeable, brittle substance, easily fractured; therefore the edges of bricks that are vitrified or turned into glass will be quickly broken off, and their surface will be slippery. Vitrification adds nothing to the strength; in fact it defeats the object for which the bricks are made.

315. The required qualities are imparted to the brick by a process of annealing. The bricks should be burned just to the point of fusion, then the heat gradually reduced until the kiln is cold. This process will produce a brick thoroughly compact, hard, and tough. If the cooling off is done quickly, it will produce a brittle brick, that will speedily go to pieces under traffic.

316. Foundation.-A solid unyielding foundation is as indis

pensable with bricks as with any other paving material: the failure of the earlier pavements was due, in many cases, more to defective foundations than to defective material. The use of plank laid on sand is objectionable for the same reasons stated under wood pavements, Articles 185, 186.

317. The foundation in all cases should be formed of cement concrete, the aggregate of which, in localities where stone or gravel are unobtainable, may be of broken bricks.

318. Manner of Laying.-The bricks should be laid on edge, as closely and compactly as possible, in straight courses across the street, with the length of the bricks at right angles to the axis of the street. Joints should be broken by at least 3 inches. None but whole bricks should be used except in starting a course or making a closure. Before the closure is made, each single course should be pressed as compactly together as possible with an iron bar applied to the curb end of the row, and then keyed in place with a close-fitting brick. After 25 or 30 feet of the pavement is laid, every part of it should be rammed with a rammer weighing not less than 50 pounds, and the bricks which sink below the general level should be removed and replaced by a brick of greater depth. After the ramming and rectification Portland-cement grout should be poured into the joints until it appears on the surface; then the whole surface should be covered with a layer of dry sand inch deep.

319. At street intersections the course should be laid meeting at an angle, as shown in Fig. 19, so that the courses may not run parallel to the traffic.

320. Cost of Brick Pavements.-The cost of construction of these pavements depends largely upon the facilities for obtaining the requisite material and the character of the foundation.

The cost of a first-class brick pavement per square yard may be