Home › Cements And Uniting Bodies › Portland Cement

Portland Cement

Portland cement is formed of clay and limestone, generally containing some silica, the properties of which may vary without injury to the cement. The proportion of clay may also vary from 19 to 25 per cent. without detriment.

The only necessary condition for the formation of a good artificial Portland cement, is an intimate and homogeneous mixture of carbonate of lime and clay, the proportion of clay being as above stated. The materials are raised to a white heat in kilns of the proper form, so that they are almost vitrified. After the calcination all pulverulent and scorified portions are carefully pricked out and thrown away. The remainder is then finely ground and becomes ready for use. The with soluble glass. Soluble soda glass of 33° amount of water which enters into combina- Baumé is to be thoroughly stirred and mixed tion with it in mixing is about.366 by weight. with fine chalk, and the coloring matter (sec It sets slowly, from 12 to 18 hours being re- 12 following receipts) well incorporated. In quired. Made into a thin solution like the course of 6 or 8 hours a hard cement will whitewash, this cement gives woodwork all set, which is capable of a great variety of the appearance of having been painted and uses.

As soluble glass can be kept on hand sanded. Piles of stone may be set together in liquid form, and the chalk and coloring with common mortar, and then the whole matters are permanent and cheap, the colored washed over with this cement, making it look cements can be readily prepared when wanted, like one immense rock of grey sandstone. and the material can be kept in stock, ready For temporary use a flour-barrel may have for use, at but little expense. Boettger re- the hoops nailed, and the inside washed with commends the following coloring matters: a little Portland cement, and it will do for a