Mortar properties; cement and sand for 10 cum

Properties of mortar

1. Workability: easy to mix, spread and lay without segregation.
2. Water retentivity: holds enough water, so bricks do not absorb it quickly.
3. Adhesion and bond strength with brick or stone.
4. Strength: adequate compressive strength (1:4 cement mortar $\approx$ 7.5 N/mm² at 28 days).
5. Durability: resists weather, frost and chemicals.
6. Proper setting time and low shrinkage.
7. Impermeable and economical.

Cement and sand for 10 cum brickwork

The question gives no data, so assume: brick 240 x 115 x 57 mm (actual size, without mortar), 10 mm joints, mortar 1:4 (cement : sand), and dry volume = 1.27 x wet volume.

Given: brickwork volume $= 10\ \text{m}^3$.

Step 1: Size of brick with mortar

$$(0.25 \times 0.125 \times 0.067) = 0.002094\ \text{m}^3$$

Step 2: Number of bricks

$$N = \frac{10}{0.002094} = 4776.1 \approx 4777\ \text{bricks}$$

Step 3: Volume of bricks without mortar

$$4777 \times 0.24 \times 0.115 \times 0.057 = 7.515\ \text{m}^3$$

Step 4: Wet volume of mortar

$$10 - 7.515 = 2.485\ \text{m}^3$$

Step 5: Dry volume of mortar (add 27% for dry bulk, voids in sand, wastage and shrinkage)

$$2.485 \times 1.27 = 3.156\ \text{m}^3$$

Step 6: Cement and sand for 1:4 (sum of ratio $= 5$)

$$\text{Cement} = \frac{1}{5} \times 3.156 = 0.631\ \text{m}^3 = 909\ \text{kg} \approx 18.2\ \text{bags (50 kg, 0.0347 m}^3\text{ each)}$$ $$\text{Sand} = \frac{4}{5} \times 3.156 = 2.525\ \text{m}^3$$

Answer: Cement = 0.631 m³ (about 18.2 bags); sand = 2.53 m³.