

LIME 



MORTAR AND CEMENT CALCIUM CARBONATE 



_'! IOIH matter by boiling is less perfectly accomplished in the case of 



t luin of cane juice. The addition of slaked lime accordingly greatly 



fates that result by the formation of insoluble lime compounds. 



M- purposes, lime enjoys a well-recognised position, mote 



especially as the basis of the mild antacid known as " lime water." 



[Cf. Waring, Baz. Med., 1897, 90-4; Barry, Legal Med., 1902, 389, 



451.] 



Mortar and Cements. By far the most important use of lime is as 

 tar a cement which consists of lime, sand and water (see pp. 292-3, ** 



If lime be mixed with water, a paste is formed that will rapidly 

 hnnl.Mi or " set," as it is called. When dry it will, however, be found to 

 crack and crumble to pieces. To prevent this it is mixed with sand (or in sd *nd 



;,i with the fine powder made from brick known as surkhi). To obviate "**< 

 a too rapid evaporation of water from the mortar, it is customary to moisten 

 the stones or bricks, when a much more durable cement is the result. If 

 ir be properly prepared, a thin layer is found sufficient to bind 

 together the materials with which it is mixed. 



Stein (Ancient Khotan, 1907) describes the stucco used in plastering Andent stucco, 

 the surfaces of walls made of wood, mud, and (sun-dried) bricks in buildings 

 uncovered by him from the sand with which they had been engulfed during 

 the 3rd to the 8th centuries. The stuccoed surfaces were found to have 

 been frescoed very elaborately and beautifully, and in many cases statues 

 made of mud were found to have been coated with stucco and subsequently 

 painted. In a further paragraph reference will again be made to Stein's 

 discoveries in connection with plaster of Paris (see p. 718). It would thus 

 seem fairly certain that anadvanced knowledge existed in Eastern Turkestan 

 of certain uses of lime long before that material came into use as a cement 

 in stone and brick construction. The oldest constructive buildings in 

 India, such as the Chulikyan temples of the Deccan, have the stones so Andent Temple*, 

 fitted into each other or are of such massive blocks that they have re- 

 mained in their positions for centuries without cement of any kind having 

 been used. It seems thus fairly certain that the use of cement in house- 

 building was subsequent to the date of the temples named. [Cf. Papers 

 Relat. to Magnesia Cement, Mad. Govt., 1826-37 ; Butler, Port. Cement, 

 1899.] 



There are commonly said to be the following classes of cements: Classiflca- 

 (a) calcareous ; (b) gelatinous ; (c) glutinous ; (d) resinous ; (e) mixed tion * 

 materials but non-resinous. The first mentioned are those with which 

 the present article is more immediately concerned, such, for example, 

 as the mortar already indicated. A hydraulic cement, or Portland cement pgfc^ ** 

 as it is called, is in other words a cement which has the property of setting 

 under water. This is obtainable from certain limestones that naturally 

 contain from 10 to 25 per cent, of alumina, magnesia and silica, or may 

 be artificially manufactured by mixing 65 to 80 parts of chalk or other 

 pure lime with 20 to 35 parts of river mud or clay and a little oxide of 

 iron, say 3 to 14 per cent. These ingredients are thoroughly mixed in 

 water, dried slowly, calcined, and then reduced to a powder. In India, 

 Portland cement is at present mainly manufactured in the Madras 

 Presidency, and more recently works have been started in Bengal, 

 but in other provinces it is occasionally prepared, and chiefly from 

 argillaceous kankar to which a certain proportion of fat limestone is 

 added. But it is a striking peculiarity of these hydraulic cements that 



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