Summary
- The base calculation shows that approximately 1.26 cement bags are used for 1 m³ of brickwork with a 1:6 mortar ratio.
- The calculation uses 190 × 90 × 90 mm bricks, 200 × 100 × 100 mm brick size with mortar, and 10 mm mortar joints to estimate the wet and dry mortar volume.
- The actual consumption of cement may vary according to brick size, size of the mortar joint, workmanship, wastage, and site conditions.
It is best to make material estimates just before doing the masonry work to save time and money on-site. In general, the quantity of cement used in 1 m³ of brickwork at a 1:6 ratio is around 55-63 kg, depending on the size of the brick and the size of the mortar joints.
Mortar joint thickness and site conditions can also affect the quality of the cement. This guide will take you through how to calculate the amount of cement required for 1 m³ of brickwork, some common errors, how to order materials, and some practical considerations that can affect the quantity.
Understanding Brickwork and Mortar Ratios
Brickwork refers to the installation of bricks and mortar for creating walls and partitions. The spaces between the bricks are filled with mortar, which holds the masonry together. 1:6 mortar ratio means that there is 1 part of cement to 6 parts of sand by volume. This ratio is used to calculate the quantity of cement required and the quality of the mortar.
Standard Assumptions for Calculating Cement in Brickwork
The calculation of cement depends on the brick size, thickness of the joint of brick, and mortar ratio used on site. Before estimating the final quantity of cement, verify these assumptions.
Use this checklist:
- Decide brick size: It is important to know if modular or non-modular bricks are needed for the project.
- Mortar joint thickness: See drawing or site standard for the thickness of the mortar joint.
- Mortar ratio: Ensure that the ratio of cement to sand is 1:6 as specified.
- Brickwork dimensions: Use the actual length, height, and thickness of brickwork.
- Openings: Take into account any openings such as doors and windows, if applicable.
Learn about the various types of bricks used in India, their sizes, and applications in the construction industry.
Step-by-Step Cement Calculation for 1:6 Brickwork
The required number of bags of 50kg cement for brickwork with a 1:6 ratio is around 1.26 bags for 1 per cubic metre. The following values are used in this calculation:
| Item | Assumed Value |
|---|---|
| Brickwork volume | 1 m³ |
| Actual brick size | 190 × 90 × 90 mm |
| Brick size with mortar | 200 × 100 × 100 mm |
| Mortar joint thickness | 10 mm |
| Ratio | 1:6 |
| Cement bag weight | 50 kg |
So, here are the steps:
Step 1: Calculate the Wet Mortar Volume
First, calculate the number of bricks in 1 m³.
Number of bricks = Brickwork volume ÷ Brick volume with mortar
= 1 ÷ (0.20 × 0.10 × 0.10)
= 500 bricks
Next, calculate the actual volume of one brick.
Volume of one brick = Length × Width × Height
= 0.19 × 0.09 × 0.09
= 0.001539 m³
Now calculate the total volume occupied by 500 bricks.
Total brick volume = Number of bricks × Volume of one brick
= 500 × 0.001539
= 0.7695 m³
Finally, subtract the brick volume from 1 m³.
Wet mortar volume = Total brickwork volume − Total brick volume
= 1 − 0.7695
= 0.2305 m³
Step 2: Calculate the Dry Mortar Volume
Convert the wet mortar volume into dry mortar volume.
A dry volume factor of 1.33 is commonly used for mortar estimation.
Dry mortar volume = Wet mortar volume × Dry volume factor
= 0.2305 × 1.33
= 0.3066 m³
Step 3: Calculate the Cement Volume for 1:6 Mortar
A 1:6 mortar ratio contains:
- 1 part cement
- 6 parts sand
- Total = 7 parts
Cement volume = Dry mortar volume × Cement part ÷ Total ratio parts
= 0.3066 × 1 ÷ 7
= 0.0438 m³
Step 4: Calculate the Volume of One Cement Bag
A standard cement bag in India weighs 50 kg. For construction estimation, 1,440 kg/m³ is commonly used as the assumed bulk density of cement.
Volume of one cement bag = Bag weight ÷ Assumed bulk density of cement
= 50 ÷ 1,440
= 0.0347 m³
Step 5: Convert Cement Volume into Bags
Now convert the required cement volume into 50 kg bags.
Cement bags = Cement volume ÷ Volume of one cement bag
= 0.0438 ÷ 0.0347
= 1.26 bags
Therefore, you need approximately 1.26 bags of cement per 1 m³ of 1:6 brickwork. Actual consumption may vary with site conditions.
Practical Tips for Ordering Cement for Brickwork
Calculate the amount of cement needed and order it according to the approved site allowance. Don't include a random percentage for wastage.
- Ensure the correct amount of cement is used, as per BOQ and drawings.
- Only include the wastage allowance approved for the project.
- Determine whether the sand is too high in silt, clay, and other materials.
- Keep cement bags in a dry and covered place.
- Don't order too much, as leftover cement can be damaged by moisture.
Read our guide about the best cement in India to learn about different types of cement, grades of cement, and the appropriate usage in construction.
Mistakes to Avoid in Brickwork Cement Calculation
Brick size, mortar ratios, or volume assumptions can cause shortages, excess materials, and inaccurate costs.
These are the usual pitfalls to be avoided:
- Using nominal brick size instead of actual brick size for brick volume.
- Forgetting to include mortar joints.
- Using the wrong mortar ratio, for example, 1:5 instead of 1:6.
- Forgetting to convert wet mortar volume to dry mortar volume.
- Assuming an estimate without referring to the BOQ or specification of the site.
Next Steps in Your Brickwork Project
Once you calculate the cement required for 1 cubic metre of brickwork, verify the quantity before placing the final order. The actual requirement may vary depending on brick size, thickness of mortar joints, and the skill level of the site work and construction techniques used in the region.
Here are the next steps:
- Verify the calculation with your mason/site engineer.
- Compare the quantity with the BOQ and drawings.
- Properly source cement and sand as per the requirements of the project.
- Properly store cement from moisture.
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Frequently Asked Questions
How much cement is needed for 1 cubic metre of brickwork?
For 1 m³ of brickwork in 1:6 mortar, you need about 1.26 bags of 50 kg cement.
What factors affect the amount of cement needed for brickwork?
The factors can be brick size, thickness of the mortar joints, ratio of the mortar, skills of the worker, and wastage.
What is the formula to calculate the cement required for brickwork?
Volume of Cement = Dry mortar volume × Cement part ÷ Total ratio parts. Then divide the volume of cement by the volume of a cement bag.
How do different mortar ratios impact the amount of cement needed for brickwork?
A richer mortar ratio, like 1:4, increases the amount of cement needed per cubic metre of brickwork, while a leaner ratio, like 1:6, decreases it.
What are the common assumptions made when calculating the amount of cement needed for brickwork?
Common assumptions include the brick size, mortar joint thickness, mortar ratio, wall dimensions, openings, and local construction practices.