I previously discussed on **How to Calculate The Total Bags of Cement for a Unit Area of Plastering**, today, I will be discussing on how you can calculate the Quantity of Cement and Sand required for **Laying Concrete Block** of 450mm by 225mm by 225mm.

As a Civil engineer, Quantity Surveyor and Site Manager on construction site, you must know this calculation in other to prevent wastage of Materials.

Always Know that** 10 Blocks** is required to Build 1m² of Wall.

**Proof:**

From the Image above, Square meter for a Block = 450mm x 225mm = 0.101 m^{2}

Now, Total Number of Blocks required for 1m² = 1/0.101 = 9.99 (say 10 blocks)

Making use of the Concrete Block Dimension Above with 25mm of Mortar Thickness, We can State the Volume of Mortal For 1m² Wall:

Volume of Horizontal Mortar = 10 Blocks × ( 0.45m × 0.225m × 0.025m) = 0.0159 m^{3}

Volume of Vertical Mortar = 8 Lines × ( 0.225m × 0.225m × 0.025m) = 0.0101 m^{3}

Total Volume of Mortar Required for Laying 1m² of Block = 0.0159 + 0.0101 = 0.026m³

Therefore the volume of mortar required to lay one square metre of 9 inches block (with hole) can be taken as 0.026m^{3} for all practical purposes.

let us assume that we have 100m^{2} of wall, and we want to estimate the quantity of cement and sand for mortar needed to lay the blocks.

The volume of mortar required = 0.026 x 100 = 2.6 m^{3}

Mix ratio for mortar (laying of blocks) is 1:6

#### CEMENT

Addition of the Mix Ratio = 7

Density of 1 bag of Cement = 1440kg/m³

Quantity of cement required = 1/7 x 1440 kg/m^{3} = 205.71 kg

Making allowance for Buckling between fresh and wet Mortar = 1.35 x 205.71 = 277.71 kg

Quantity of cement required in bags = 277.71/50 = 5.55 bags

**5.55 bags of Cements = 1m³ of Mortar**

For 2.6m³ which Cover 100m² of Concrete Blocks

**5.55 bags of Cements = 1m³ of Mortar**

**X bags of Cements = 2.6m³ of Mortar**

X = 14.43 bags of Cement

14.43 Bags of Cement is Required for Laying of 100m² Concrete Block.

#### SAND

Addition of the Mix Ratio = 7

Density of Sand = 1600kg/m³

Quantity of Sand required = 6/7 x 1600 kg/m^{3} = 1371.428 kg

Making allowance for Buckling between fresh and wet Mortar = 1.35 x 1371.428 = 1851.43 kg

**1.85 Tons of Sand = 1m³ of Mortar**

For 2.6m³ which Cover 100m² of Concrete Blocks

**1.85 Tons of Sand = 1m³ of Mortar**

**X Tons of Sand = 2.6m³ of Mortar**

X = 4.6 Tons of Sand

4.6 Tons of Sand is Required for Laying of 100m² Concrete Block.

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