242 



CHEMISTRY OF FARM PRACTICE 



192. Quantity of Materials for a Given Mixture. Con- 

 crete is a manufactured stone and the object is to fill the 

 interstices between the gravel with sand and those between 

 the sand particles with cement, hence the volume of con- 

 crete is just about represented by the volume of crushed 

 stone or gravel. A mixture consisting of one part by vol- 



Cement 



FIG. 78. Required quantities of cement, sand, and stone or gravel 

 for a 1 : 2 : 4 concrete mixture and the resulting quantity of con- 

 crete. (Bulletin 461, U. S. Dept. Agr.) 



ume of cement, and two parts of sand and four parts of stone 

 or gravel, is often used. Table XXIV gives the quantities 

 of the various materials for cement or concrete mixtures; 

 the relative values are shown in Fig. 78. 



TABLE XXIV. QUANTITIES OF MATERIALS AND THE 

 RESULTING AMOUNT OF CONCRETE FOR A TWO- 

 BAG BATCH. 



(Farmer's Bulletin 461, U. S. Dept. Agr.) 



