Concrete Mix Calculator Sand Gravel Cement

Concrete Mix Formulas:

\[ \text{Cement (kg)} = \left[\text{Volume (m³)} \times 1.54 \times \left(\frac{1}{1 + \text{sand ratio} + \text{gravel ratio}}\right)\right] \times 1440 \] \[ \text{Sand (m³)} = \text{Volume (m³)} \times 1.54 \times \left(\frac{\text{sand ratio}}{1 + \text{sand ratio} + \text{gravel ratio}}\right) \] \[ \text{Gravel (m³)} = \text{Volume (m³)} \times 1.54 \times \left(\frac{\text{gravel ratio}}{1 + \text{sand ratio} + \text{gravel ratio}}\right) \]

Volume:

m³

Sand Ratio:

(e.g., 1.5 for M20)

Gravel Ratio:

(e.g., 3 for M20)

Cement Density:

kg/m³

Cement Required:

Sand Required:

Gravel Required:

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1. What is Concrete Mix Calculation?

This calculator determines the quantities of cement, sand, and gravel needed for a specific volume of concrete based on mix ratios (e.g., M20 ratio 1:1.5:3). It accounts for the density of materials and volume calculations.

2. How Does the Calculator Work?

The calculator uses these formulas:

\[ \text{Cement} = \left[\text{Volume} \times 1.54 \times \left(\frac{1}{1 + \text{Sand} + \text{Gravel}}\right)\right] \times \text{Density} \] \[ \text{Sand} = \text{Volume} \times 1.54 \times \left(\frac{\text{Sand Ratio}}{1 + \text{Sand} + \text{Gravel}}\right) \] \[ \text{Gravel} = \text{Volume} \times 1.54 \times \left(\frac{\text{Gravel Ratio}}{1 + \text{Sand} + \text{Gravel}}\right) \]

Where:

Volume — Total concrete volume needed (m³)
Sand Ratio — Proportion of sand in mix (e.g., 1.5)
Gravel Ratio — Proportion of gravel in mix (e.g., 3)
1.54 — Conversion factor for dry volume to wet volume
Density — Cement density (typically 1440 kg/m³)

3. Importance of Accurate Mix Ratios

Details: Proper mix ratios ensure concrete strength, durability, and workability. Incorrect ratios can lead to weak structures or wasted materials.

4. Using the Calculator

Tips: Enter volume in cubic meters, sand and gravel ratios (e.g., 1.5 and 3 for M20 mix), and cement density (default 1440 kg/m³). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the 1.54 factor?
A: It accounts for the increase in volume when mixing dry materials with water (bulking factor).

Q2: What are common mix ratios?
A: M10 (1:3:6), M15 (1:2:4), M20 (1:1.5:3), M25 (1:1:2) - cement:sand:gravel.

Q3: Why is cement measured in kg while aggregates in m³?
A: Cement is typically purchased by weight, while sand and gravel are often measured by volume.

Q4: Should I account for wastage?
A: Yes, add 5-10% extra to calculated amounts to account for spillage and compaction.

Q5: How does this differ for other mix designs?
A: For special mixes (e.g., with admixtures or different aggregates), professional mix design is recommended.