QUANTITIES OF MATEEIALS 279 



Thus the quantity of lime required for the above wall = f §£g = 1-3 

 cubic yards. 



The quantities of lime and sand required for mortar for rubble 

 masonry may be calculated from the relation that 1 cubic yard of rubble 

 masonry requires from £ to 1 of a cubic yard of mortar. 



One-fourth of a cubic foot of mortar will point 1 square yard of 

 brickwork in English bond. 



The quantities of cement and sand required to make the mortar for 

 pointing any particular area of brickwork may be calculated from the 

 table on p. 135, according to the richness of the mortar to be used. 



For a plaster coating of 1 : 3 lime mortar having an average thickness 

 of | inch, we may assume that 1 cubic foot of lime will be required for 

 each 4 square yards of surface of brickwork to be covered. 



Concrete. — In order to calculate the quantities of cement, sand, and 

 broken stone required for a concrete wall, or floor, etc., we must — 



(1) Calculate the volume of the wall or floor in question. It will be 



convenient to express this volume in cubic yards. In the case 

 of a wall the volume will be 



= length in yards X height in yards X thickness in yards ; 



and in the case of a floor 



= length in yards X width in yards X thickness in yards. 



(2) Select from the table on p. 130 the figures corresponding to the 



relative proportions of cement, sand, and broken stone which it 



is desired to use, and multiply each of these figures in turn by 



the number of cubic yards in the wall or floor. The results will 



represent the total quantities of cement (barrels), sand (cubic 



yards), and broken stone (cubic yards), which will be required. 



Example. — A concrete floor is 90 feet long, by 30 feet wide, by 



4 inches thick. The concrete is to be mixed in the proportions 1 : 2£ : 5, 



i.e. 1 part cement, to 2£ parts sand, to 5 parts broken stone. Calculate 



the quantities of cement, sand, and broken stone required. 



(1) Length of floor = 90 feet = 30 yards ; 

 Width „ = 30 feet =10 yards ; 



Thickness „ =4 inches = £ yard. 



Hence— 



Volume of floor 



= 33 3 cubic yards. 



Volume of floor = 30 X 10 X I 



