Estimate Gravel, Cement and Sand for Plain Cement Concrete work

Purpose

This calculator estimates material quantities and labour effort for a plain cement concrete (PCC) block based on entered dimensions, mix parts, and productivity assumptions.

It helps you plan how much cement, sand, gravel, and labour mandays are needed for a defined concrete volume.

Background

What this estimate represents

The calculator treats the concrete work as a rectangular volume. It then applies a dry-volume factor and splits that dry volume into cement, sand, and gravel according to the entered mix parts.

Inputs

• Work Thickness: Concrete thickness.
• Work Length: Concrete length.
• Work Width: Concrete width.
• Cement Sand Gravel Ratio: Cement part of the concrete mix.
• Sand Part: Sand part of the concrete mix.
• Gravel Part: Gravel part of the concrete mix.
• Mortar Dry Volume Factor: Multiplier used to convert wet concrete volume to dry material volume.
• Cement Bag Volume: Volume represented by one bag of cement for bag conversion.
• Skilled Labour: Skilled productivity as volume per manday.
• Unskilled Labour: Unskilled productivity as volume per manday.

Results

• Cement: Estimated cement quantity in bag.
• Sand: Estimated sand quantity in cft.
• Gravel: Estimated gravel quantity in cft.
• CC Work Volume: Total concrete work volume in cft.
• Skilled Labour: Estimated skilled labour effort in manday.
• Unskilled Labour: Estimated unskilled labour effort in manday.

Understanding the Calculation

All entered dimensions are converted to inches internally.

1. Work volume:

$$V_{work}=L\times W\times T$$

2. Dry material volume:

$$V_{dry}=V_{work}\times f_{dry}$$

3. Mix parts total:

$$P=c+s+g$$

where $c$ is Cement Sand Gravel Ratio, $s$ is Sand Part, and $g$ is Gravel Part.

4. Material split:

$$V_{cement}=V_{dry}\times \frac{c}{P}$$

$$V_{sand}=V_{dry}\times \frac{s}{P}$$

$$V_{gravel}=V_{dry}\times \frac{g}{P}$$

Cement is converted to bags using Cement Bag Volume. Sand and gravel are converted to cubic feet for display.

5. Labour mandays:

$$M_{skilled}=\frac{V_{work}}{R_{skilled}}\quad , \quad M_{unskilled}=\frac{V_{work}}{R_{unskilled}}$$

where $R$ values are the entered productivity rates.

Example

Example scenario:

• Work Length 10 ft, Work Width 15 inch, Work Thickness 3 inch
• Mix parts: Cement Sand Gravel Ratio 1.0, Sand Part 2.0, Gravel Part 4.0
• Mortar Dry Volume Factor 1.4
• Labour productivity: Skilled 10 cft/manday, Unskilled 10 cft/manday

Expected interpretation:

• Increasing work dimensions increases all material outputs and labour mandays.
• Increasing Mortar Dry Volume Factor increases Cement, Sand, and Gravel.
• Increasing labour productivity rates decreases required mandays.

Important Assumptions and Interpretation

• The work shape is modeled as a rectangular block.
• Mix parts are proportional shares of dry volume.
• Labour outputs are effort estimates from simple division, not project schedules.
• The function does not enforce explicit input validation for unrealistic values; use physically meaningful units and quantities.
• This step estimates quantities and effort, not direct money cost.