282 PAEM BUILDINGS IN SOUTH AFRICA 



that is — 



Volume of thin inner part ) 



/ • a r -i s = 32 cutic feet - 

 of base (i.e. floor of silo) J 



Therefore, 



Total volume of concrete in silo = 605 + 169 + 32 



= 806 cubic feet. 



Now there are 27 cubic feet in a cubic yard, hence — 



Total volume of concrete in silo = -^S- 



= 29 8 cubic yards. 



Referring to the table on page 130 we find that T57 barrels of cement 

 are required for 1 cubic yard of 1 : 2 : 4 concrete ; therefore the quantity of 

 cement required for 29*8 cubic yards of concrete 



= 1-57 X 29-8 

 = 47 barrels, 

 or 94 bags. 



Again referring to the table on page 130, we see that 0*44 cubic yard 

 of sand is required per cubic yard of 1 : 2 : 4 concrete, hence — 



Sand required for 298 cubic yards concrete = 044 X 29'8 



= 131, say 13i cubic yards; 



and, 



broken stone required = 26£ cubic yards. 



Cement Plaster or Mortar. — For the purpose of calculating the quan- 

 tities of materials required for cement plaster or mortar, made with 

 fine sand, the table given on page 135 may be used. 



Example. — A concrete wall 120 feet long by 8 feet high is to be 

 rendered on one side with a coat of cement plaster averaging £ inch in 

 thickness. The plaster is in the proportion 1 part cement to 3 parts 

 fine sand. Calculate the quantities of cement and sand required. 

 Volume of compacted plaster in cubic yards 



(length of wall) (height of walll (thickness of plaster I 

 I in yards f | in yards j ( coat in yards ) 

 Now, length of wall = 120' = 40 yards 

 height „ = 8' = f yards 



3 



thickness of plaster coat = f " = g yard 



= ?V y ard - 



