Concrete Tile

CONCRETE TILE Cost of Concrete Tile. The cost of producing tile is not the same in all sections, owing chiefly to variations in freight rates. One estimate, based on a machine cost, is as follows: In the making of concrete tile, the same gen eral principles apply that rule in other concrete work. It is absolutely necessary to use only the best of materials.

Sand.

This should be clean and sharp, and should be well graded. Large stones are not ad visable. No loam should be used, but a very small quantity of clay is allowable, and helps to make the product waterproof.

Cement.

The best cement, that which will pass the test of the American Society for Test ing Materials, is recommended.

Mixing.

Whether the mixing is done by machinery or by hand is of little consequence, so long as the operation is thorough. If tile in any large quantity are to be made, the machine method will be found more economical. The vital point about concrete is to produce a tile that will hold water, and the whole matter de pends more upon the mixing than upon anything else, although there should be no skimping of cement.

Machines.

There are several good tile ma chines on the market that have proved their worth in actual practice.

In making the smaller sizes of tile, some ma chines use no pallets, the moulds holding the tile until they can be placed upon boards, on cars or racks, when the mould is released. Where it is possible, use cars to carry the product from the machine. It is probable that the car system is preferable to the rack system for handling the product, as it saves handling the tile twice, and the convenience of cars is increased where steam-curing is practiced. The number of tile handled naturally depends entirely upon the capacity of the machine used and the number of men employed. The average machine, with a crew of seven men, will turn out from 300 to 500 perfect tile an hour, in sizes ranging from 4 to 12 inches. It will be seen that with from 3,000 to 5,000 tile to dispose of in every working day of ten hours, the matter of racking them is of greatest importance, as time lost is money lost.

In using cars, the tile can be stacked three tiers high and run away from the machine to the curing room, to stand there until they can be run to the yard. In this way the tile are handled but twice—once to the cars from the machine, and once from the cars to the racks or ground pile in the yard.

If the tile are cured on racks, these can, of course, be built as high as it is considered prac ticable to reach.

A plant may be arranged with little expense. Select a room that can be closed up tight, in the absence of a regular brick-walled kiln, and run your steam pipes under the floor. Use damp steam, turning it into the room under not more than 5 pounds pressure. The combi nation of warmth and moisture hastens the set ting, and provides for perfect crystallization. Tile are of course much more quickly cured by this method than by any other. Steam is not turned onto the product until it is 12 hours old, and the tile are left in the kiln from 18 to 24 hours after the steam is applied.

A steam-curing kiln may be operated without a boiler, if it is necessary. Place thin sheets of sheet iron over gas jets or gasoline torches and let water drip onto them from above. The water is turned into steam as soon as it touches the hot iron and the resultant heat and moisture do the curing.

Ageing.

Tile should be aged for from 30 to 60 days before being used. It is poor policy to attempt to rush matters and use tile before they are properly aged, as the tile are very apt to fail later because of this oversight.

Freezing. It is impossible to harm a cement tile by freezing and thawing, after it is two days old. Tile can be hauled with perfect safety in freezing weather, and they are not injured by being left on the ground throughout the winter, while clay tile would disintegrate under such conditions.