CHAPTER XIV. 

 EMINENTLY HYDRAULIC LIMES: GRAPPIER CEMENTS. 



THE hydraulic limes are usually, compared to Portland or good 

 natural cements, only feebly hydraulic. This fact, taken in connection 

 with the abundance of materials suitable for the manufacture of natu- 

 ral cements, has prevented the introduction of hydraulic-lime manu- 

 facture into the United States, though in Europe the industry is of 

 considerable importance. No hydraulic lime is at present made in 

 this country, nor is there any prospect that the industry will ever be 

 taken up here. A considerable amount of hydraulic lime and grappier 

 cement is, however, annually imported. This is brought about by 

 the fact that these products, being low in iron and soluble salts, are 

 light colored and do not stain masonry. There is thus a fair market 

 for them for architectural rather than for engineering uses. A promi- 

 nent brand of grappier cement much used in the United States as a 

 41 non-staining cement " is called Lafarge. 



The manufacture and properties of the hydraulic limes and grappier 

 cements will be discussed briefly. This discussion will be practically 

 confined to the practice followed at Teil, France, where the largest 

 and best-known plants are located. 



Composition of the ideal hydraulic lime. The clinker of an ideal 

 hydraulic lime should, as may be deduced from the considerations set 

 forth in the preceding chapter, satisfy two limiting conditions. On 

 the one hand, it must contain sufficient free lime to disintegr te the 

 entire mass of clinker by the force of its own slaking. On the other 

 hand, no more free lime should be present than is absolutely necessary 

 to effect this disintegration; and no uncombined silica or alumina 

 should be present in the clinker. This ideal condition would be arrived 

 at, according to Le Chatelier,* if we could obtain a clinker containing 

 four equivalents of lime for one of silica. Three of the four equiva- 

 lents of lime would be united with all the silica to form tricalcic sili- 

 cate, while the fourth equivalent of lime would remain free, and would 



; 9 _ 



* Trans. Am. Inst. Min. Eng., vol. 22, p. 16. 



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