Mortar Calculation: Precision in Construction Material Estimation

Mortar calculation is the process of determining the exact quantity of mortar required for masonry work. It ensures efficient resource use and cost control in construction projects.

This article covers detailed formulas, common values, and real-world examples for accurate mortar calculation. It is designed for professionals seeking expert-level understanding and application.

Calculadora con inteligencia artificial (IA) para Mortar Calculation

• Calculate mortar volume for a 10m² brick wall with 20mm joint thickness.
• Determine cement and sand quantities for 1 cubic meter of mortar (1:4 mix ratio).
• Estimate mortar needed for laying 500 concrete blocks, each 400x200x200 mm.
• Find mortar volume loss due to wastage at 5% for a 50m² stone masonry.

Comprehensive Tables of Common Mortar Calculation Values

Fundamental Formulas for Mortar Calculation

Mortar calculation involves determining the volume of mortar required based on masonry dimensions, brick/block size, and joint thickness. The key formulas are explained below with detailed variable descriptions.

1. Mortar Volume for Brickwork

The mortar volume (V_m) required for brick masonry can be calculated as:

• V_m: Mortar volume (m³)
• V_t: Total masonry volume (m³)
• P_m: Mortar volume percentage (decimal form, e.g., 0.22 for 22%)

The mortar volume percentage depends on brick size and joint thickness, typically ranging from 18% to 25%.

2. Total Masonry Volume

Calculated as the product of wall area and thickness:

• A: Wall area (m²)
• T: Wall thickness (m)

3. Mortar Quantity Based on Brick Count

Alternatively, mortar volume can be estimated from the number of bricks (N) and mortar volume per brick (V_mb):

• N: Number of bricks
• V_mb: Mortar volume per brick (m³)

V_mb is derived from brick dimensions and joint thickness, accounting for the voids between bricks.

4. Cement and Sand Quantities in Mortar

Given the mortar volume, the quantities of cement and sand can be calculated using the mix ratio and material densities:

• C: Cement part in mix ratio (e.g., 1 in 1:4)
• S: Sand part in mix ratio (e.g., 4 in 1:4)
• ρ_c: Cement density (kg/m³), typically 1440 kg/m³
• W_loss: Wastage factor (decimal), usually 0.05 (5%)

Water quantity depends on workability and is generally 30-40% of cement weight.

5. Adjusting for Mortar Shrinkage and Compaction

Mortar volume after mixing shrinks due to water evaporation and compaction. To account for this, a correction factor (K) is applied:

• V_m,wet: Wet mortar volume before shrinkage (m³)
• K: Correction factor, typically 1.33 to 1.5

This factor ensures sufficient mortar is prepared to compensate for volume reduction.

Detailed Explanation of Variables and Common Values

• Wall Area (A): Measured in square meters (m²), it is the surface area of the wall to be constructed.
• Wall Thickness (T): Thickness of the masonry wall, usually equal to the brick length or block width, measured in meters.
• Mortar Volume Percentage (P_m): The proportion of mortar volume relative to total masonry volume, influenced by brick size and joint thickness.
• Number of Bricks (N): Total bricks or blocks used in the masonry.
• Mortar Volume per Brick (V_mb): Volume of mortar required per brick, accounting for joint thickness and brick dimensions.
• Mix Ratio (C:S): Ratio of cement to sand by volume, commonly 1:3, 1:4, or 1:5 depending on strength requirements.
• Cement Density (ρ_c): Bulk density of cement, approximately 1440 kg/m³.
• Wastage Factor (W_loss): Percentage of material loss during mixing and application, typically 5%.
• Correction Factor (K): Accounts for shrinkage and compaction of mortar, usually between 1.33 and 1.5.

Real-World Application Examples of Mortar Calculation

Example 1: Mortar Volume for a Brick Wall

A contractor needs to build a brick wall measuring 10 meters long, 3 meters high, and 0.2 meters thick. The bricks used are 230 x 110 x 76 mm with a 12 mm mortar joint. Calculate the volume of mortar required.

Step 1: Calculate Wall Area and Volume

• Wall area (A) = length × height = 10 m × 3 m = 30 m²
• Wall thickness (T) = 0.2 m
• Total masonry volume (V_t) = A × T = 30 × 0.2 = 6 m³

Step 2: Determine Mortar Volume Percentage

• From the table, mortar volume percentage for 230 x 110 x 76 mm bricks with 12 mm joints is approximately 21.5% (0.215)

Step 3: Calculate Mortar Volume

Step 4: Adjust for Shrinkage

• Using correction factor K = 1.4

Step 5: Calculate Cement and Sand Quantities (Mix 1:4)

• Cement part (C) = 1
• Sand part (S) = 4
• Total parts = 5
• Cement volume = 1.806 × (1/5) = 0.3612 m³
• Sand volume = 1.806 × (4/5) = 1.4448 m³
• Cement weight = 0.3612 × 1440 = 520 kg (approx.)
• Sand volume remains 1.44 m³

The contractor should prepare approximately 1.8 m³ of wet mortar, containing 520 kg of cement and 1.44 m³ of sand.

Example 2: Mortar Calculation for Concrete Block Masonry

A builder is constructing a wall using concrete blocks sized 400 x 200 x 200 mm. The wall dimensions are 8 m long, 2.5 m high, and one block thick. Mortar joints are 15 mm thick. Calculate the mortar volume and material quantities for a 1:5 mortar mix.

Step 1: Calculate Wall Volume

• Wall area (A) = 8 × 2.5 = 20 m²
• Wall thickness (T) = 0.2 m (block thickness)
• Total masonry volume (V_t) = 20 × 0.2 = 4 m³

Step 2: Mortar Volume Percentage

• From the table, mortar volume percentage for concrete blocks with 15 mm joints is approximately 18.2% (0.182)

Step 3: Calculate Mortar Volume

Step 4: Adjust for Shrinkage

• Correction factor K = 1.4

Step 5: Calculate Cement and Sand Quantities

• Mix ratio 1:5 → total parts = 6
• Cement volume = 1.019 × (1/6) = 0.1698 m³
• Sand volume = 1.019 × (5/6) = 0.8492 m³
• Cement weight = 0.1698 × 1440 = 244.5 kg

The builder should prepare approximately 1.02 m³ of wet mortar, including 245 kg of cement and 0.85 m³ of sand.

Additional Considerations for Accurate Mortar Calculation

• Material Moisture Content: Sand moisture affects volume and water demand; dry sand requires more water.
• Mortar Type: Different applications require varying mix ratios, e.g., lime mortar for historic buildings.
• Wastage and Spillage: Always include a wastage factor (5-10%) to avoid shortages.
• Joint Thickness Variability: Field conditions may alter joint thickness, impacting mortar volume.
• Compaction and Workability: Overly dry or wet mortar affects volume and strength.

Authoritative Resources for Mortar Calculation Standards

• ASTM C270 – Standard Specification for Mortar for Unit Masonry
• ISO 22965-1:2017 – Masonry mortar – Part 1: Specification
• National Ready Mixed Concrete Association (NRMCA)
• Portland Cement Association (PCA)

Accurate mortar calculation is essential for optimizing material use, ensuring structural integrity, and controlling costs in masonry construction. By applying the formulas, tables, and considerations detailed above, professionals can achieve precise estimations tailored to project requirements.