Determine the approximate proportion of dry cement mortar required for brick work with bricks of nominal size 19 cm x 9 cm x 9 cm, with 18 % extra for frog filling and wastage is : (assume 1 m³ of wet mortar = 1.3 m³ of dry mortar):

Calculation:

Size of brick = 190 × 90 × 90 mm³

Let mortar thickness = 10 mm

Size of brick with mortar = 0.19 + 0.01 = 0.20, 0.09 + 0.01 = 0.1, 0.09 + 0.01 = 0.1

Volume of brick with mortar = 0.2 × 0.1 × 0.1 = 0.002 m³

No. of bricks in 1 m³ = 1/0.002 = 500 Nos.

Volume of 500 bricks without mortar = 500 × 0.19 × 0.09 × 0.09 = 0.7695 m³

Volume of mortar = 1-0.7695 = 0.2305 m³

18 % extra mortar for frog filling and wastage is considered.

So volume ofmortar = 1.18 × 0.2305 = 0.27199m³

Volume of dry mortar = 1.3 × .27199 = 0.353 m³

Percentage of dry mortar = (0.353/1) × 100 = 35.3%