M30 Material calculations; bricks 1m3, Plastering 1m3 material calculations

Complete Guide to Brick, Plaster, Steel, and RCC Concrete Calculations 

When working on construction projects—whether it’s a small residential building or a large-scale commercial project—accurate material estimation is essential. Civil engineers rely on standard formulas and ratios to calculate the number of bricks, quantity of plaster, steel reinforcement weight, and RCC concrete mix requirements.

In this guide, we will walk through step-by-step calculations for:

• Brickwork estimation

• Plastering requirements

• Steel bar weight calculations

• RCC concrete mix design (M15 to M30)

• Cement, sand, and aggregate ratios with examples

These calculations are based on standard engineering practices and IS codes, ensuring that the results are both practical and reliable.

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🔹 1. Brickwork Calculations

Standard Brick Size in India

• Nominal brick size: 190 mm × 90 mm × 90 mm

• Volume of one brick:

$$\text{Volume} = 0.19 \times 0.09 \times 0.09 = 0.001539 \, m^3$$

Number of Bricks in 1 m³ of Masonry

$$\text{No. of bricks} = \frac{1}{0.001539} \approx 650 \, \text{bricks}$$

➡️ Conclusion: For 1 cubic meter of brickwork, approximately 650 bricks are required (excluding mortar thickness).

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🔹 2. Plastering Calculations

Plaster Thickness

For a standard plaster thickness of 12 mm (0.012 m):

• Volume of plaster per 1 m² area

$$1 \times 1 \times 0.012 = 0.012 \, m^3$$

Mortar Density

• Density of mortar = 2200 kg/m³

• Mix ratio = 1:6 (Cement : Sand)

• Sum of proportion = 7

Cement & Sand Required (for 1 m³ of mortar)

$$\text{Cement} = \frac{1}{7} \times 2200 = 315 \, kg$$ $$\text{Sand} = \frac{6}{7} \times 2200 = 1885 \, kg$$

For 1 m² Plaster Area

• Cement = 0.012 × 315 = 3.78 kg

• Sand = 0.012 × 1885 = 22.62 kg

➡️ Conclusion: To plaster 1 m² wall area (12 mm thick), you need approx. 3.8 kg cement and 22.6 kg sand.

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🔹 3. Steel Bar Weight Calculation

In RCC (Reinforced Cement Concrete) works, steel reinforcement plays a vital role. To calculate steel weight, civil engineers use a standard formula:

Formula

$$\text{Weight (kg)} = \frac{D^2}{162.5} \times L$$

Where:

• D = Diameter of bar (mm)

• L = Length of bar (m)

Example – 12 mm Bar of 3 m Length

$$\text{Weight} = \frac{12^2}{162.5} \times 3 = 2.65 \, kg$$

➡️ Conclusion: A 12 mm bar of 3 m weighs 2.65 kg.

Steel Grades

• Fe415: Contains ~0.30% carbon

• Fe415D & Fe415S: Improved ductility with max 0.25% carbon

• Sulphur & Phosphorous content:

  • Fe415: Max 0.060%

  • Fe415D/S: Max 0.045%

  • Combined S+P: 0.110% (Fe415), 0.085% (Fe415D/S)

These chemical properties influence strength, ductility, and corrosion resistance in RCC works.

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🔹 4. RCC Concrete Mix Ratios

Concrete is classified by grades (M15, M20, M25, M30, etc.), where “M” denotes mix and number indicates compressive strength (N/mm²) after 28 days.

Nominal Mix Proportions

Grade	Cement : Sand : Aggregate	Cement (bags/m³)	Sand (cft)	Aggregate (cft)
M15	1:3:6	4.5	16.04	32.07
M20	1:2:4	6	14.98	29.96
M25	1:1.75:3.5	6.75	14.75	29.14
M30	1:1.5:3	7.5–8	18.06	32.11

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🔹 5. Detailed Example: M30 Concrete Mix Design

Cement Density

• Density of cement = 1440 kg/m³

• Volume of 1 kg cement = 1/1440 = 0.00069 m³

• Volume of 50 kg cement bag = 0.0347 m³

Sand & Aggregate Ratios

• For M30 → Cement : Sand : Aggregate = 1 : 1.5 : 3

So, for 1 bag of cement (50 kg):

• Sand volume = 0.0347 × 1.5 = 0.0521 m³

• Aggregate volume = 0.0347 × 3 = 0.104 m³

Conversion to Weight

• Sand weight = 0.0521 × 1600 = 83.33 kg

• Aggregate weight = 0.104 × 1450 = 151.04 kg

➡️ Conclusion: 1 bag of cement requires 83.3 kg sand + 151 kg aggregate for M30 concrete.

Concrete Yield per Bag

• Total concrete weight (cement + sand + aggregate + water) ≈ 312 kg

• Density of concrete ≈ 2400 kg/m³

• Volume of concrete from 1 bag ≈ 0.13 m³

$$\text{Bags required for 1 m³} = \frac{1}{0.13} \approx 7.7 \, bags$$

Thus, for 1 m³ of M30 concrete, you need:

• 7.7 bags cement (~385 kg)

• 641 kg sand

• 1162 kg aggregate

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🔹 6. Alternative Cement-Sand-Aggregate Calculation

Another method uses the dry-to-wet factor (1.54):

• Total ratio = 1 + 1.5 + 3 = 5.5

Cement

$$= 1.54 \times \frac{1}{5.5} \times 1440 = 403.2 \, kg \, \approx 8 \, bags$$

Sand

$$= 1.54 \times \frac{1.5}{5.5} \times 1600 = 672 \, kg$$

Aggregate

$$= 1.54 \times \frac{3}{5.5} \times 1450 = 1218 \, kg$$

➡️ Conclusion: This method confirms that approx. 8 bags of cement, 672 kg sand, and 1218 kg aggregate are needed for 1 m³ of M30 concrete.

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🔹 7. Density Reference Values

Material	Density (kg/m³)
Cement	1440
Sand (loose)	1600
Aggregate	1450
Concrete	2400

These values are approximations and may vary depending on source, moisture content, and compaction.

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🔹 FAQs on Material Calculations

Q1. How many bricks are required for 1 m³ of wall?

Approximately 650 bricks of standard size (190 × 90 × 90 mm).

Q2. How much plaster is needed for 1 m² area?

For 12 mm plaster, you need 3.8 kg cement + 22.6 kg sand.

Q3. What is the formula for steel bar weight?

$$\text{Weight} = \frac{D^2}{162.5} \times L$$

Q4. How many bags of cement are required for 1 m³ of M30 concrete?

Approximately 7.7–8 bags of cement.

Q5. What is the density of RCC concrete?

Standard RCC concrete density is 2400 kg/m³.

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🔹 Final Thoughts

Accurate construction material estimation is the backbone of project cost control. Engineers and contractors use these standard calculations to ensure structural safety, cost efficiency, and material optimization.

Whether it’s brickwork, plastering, steel reinforcement, or RCC mix design, mastering these formulas helps in:

• Avoiding material wastage

• Ensuring structural quality

• Reducing project costs

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⚠️ Disclaimer: The above calculations are based on standard engineering practices and may vary depending on local material properties, site conditions, and IS codes. Always consult a licensed civil engineer before applying these values in actual construction projects.

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