The unit weight of construction materials is a critical parameter in the field of civil engineering and construction. Also known as specific weight or density, unit weight is the measure of the weight of a material per unit volume. This property is crucial in structural design, construction planning, and material selection. In this article, we will explore the concept of unit weight, its significance, and the unit weights of common construction materials.
What is Unit Weight?
The unit weight of a material, also known as specific weight or density, is the weight of a substance per unit volume. It is typically denoted by the symbol “\( \gamma \)” (gamma) and mathematically, it is expressed as:
where:
- \( gamma \) is the unit weight,
- \( W \) is the weight of the material,
- \( V \) is the volume of the material.
Unit of Unit Weight
The units of unit weight depend on the system of measurement used. The common units for unit weight:
- In the International System of Units (SI), the unit weight is typically measured in kilograms per cubic meter (kg/m³).
- In the Imperial or US Customary System, the unit weight is commonly expressed in pounds per cubic foot (lb/ft³).
Unit Weight Calculator
Unit conversion
The unit conversion between the imperial system to international system is done as follows.
- 1kg/m3 = 0.064243 lb/ft3
- 1lb/ft3 = 16.018kg/m3
Unit Weights for Common Construction Materials
The unit weight for the different building construction materials is as follows: –
| S.No. | Materials | Unit Weight | ||
|---|---|---|---|---|
| In kilograms per cubic meter (kg/m3) | In kilonewton per cubic meter (kN/m3) | In pounds per cubic foot (lb/ft3) | ||
| 1. | Concrete | |||
| 1.1 | Reinforced Cement Concrete | 2500 | 25.00 | 156.00 |
| 1.2 | Plain Cement Concrete (normal-weight concrete) | 2400 | 24.00 | 149.82 |
| 1.3 | Lime concrete | 1900 | 19.00 | 118.56 |
| 2. | Mortar | |||
| 2.1. | Cement mortar | 2080 | 20.80 | 129.79 |
| 2.2. | Lime mortar | 1600 to 1920 | 16.00 to 19.20 | 99.84 to 114.82 |
| 3. | Other Construction Materials | |||
| 3.1. | Cement | 1440 | 14.40 | 89.86 |
| 3.2 | Brick (for more) | 1600 to 1920 | 16.00 to 19.20 | 99.88 to 119.81 |
| 3.3 | Brick masonry | 1920 | 19.20 | 119.81 |
| 3.4 | Asphalt | 2243 | 22.43 | 139.963 |
| 3.5 | Gypsum Powder | 1410 to 1760 | 14.10 to 17.6 | 87.98 to 109.82 |
| 3.6 | Steel | 7850 | 78.50 | 466.75 |
| 3.7 | Bitumen | 1040 | 10.40 | 64.89 |
| 3.8 | Sand (dry) | 1540 to 1600 | 15.40 to 16.00 | 96.09 to 99.84 |
| 3.9 | River Sand | 1760 to 2000 | 17.60 to 20.00 | 124.86 |
| 3.10 | Soil (damp) | 1760 | 17.60 | 109.87 |
| 3.11 | Marble | 2620 to 2720 | 26.20 to 27.20 | 163.488 to 169.80 |
| 3.12 | Timber | 400 to 800 | 40.00 to 80.00 | 24.97 to 49.94 |
Unit weight for Bricks and Blocks
Unit weights for bricks and blocks are tabulated below:
| S.No. | Bricks and Block | Unit Weight | |
|---|---|---|---|
| Kg/m3 | lb/ft3 | ||
| 1. | Burnt Clay Bricks | 1920 | 119.81 |
| 2. | Cement Concrete Brick | 1800 | 112.32 |
| 3. | Engineering Bricks | 2000 to 2200 | 124.85 to 137.34 |
| 4. | Fly Ash Bricks | 1468 to 1700 | 91.60 to 106.08 |
| 5. | AAC Block | 450 to 1000 | 28.09 to 62.43 |
| 6. | Concrete Block | 1760 to 2080 | 109.87 to 129.85 |
| 7. | Hollow Concrete Block | 2000 to 2240 | 124.85 to 129.85 |
| 8. | Interlocking Concrete Block | 1600 to 1840 | 99.88 to 114.87 |
Also, read: 11 Types Of Bonds In Brick Masonry Wall Construction
Unit Weight for Natural Stones
| S.No. | Stones | Unit Weight | |
|---|---|---|---|
| Kg/m3 | lb/ft3 | ||
| 1. | Igneous Stones | ||
| 1.1 | Basalt | 2850 to 2960 | 177.92 to 184.79 |
| 1.2 | Granite | 2400 to 2690 | 149.76 to 167.85 |
| 1.3 | Gabbro | 2800 to 3040 | 174.80 to 189.78 |
| 2. | Sedimentary Stones | ||
| 2.1 | Limestone | 2400 to 2720 | 149.76 to 169.73 |
| 2.2 | Sandstone | 2250 to 2400 | 140.4 to 149.76 |
| 2.3 | Laterite stone | 1019 | 64.89 |
| 2.4 | Dolomite | 2899 | 181.00 |
| 3. | Metamorphic Stones | ||
| 10. | Geniss | 2640 to 2880 | 164.80 to 179.79 |
| 11. | Marble | 2620 to 2720 | 163.488 to 169.80 |
| 12. | Limestone | 2720 to 2880 | 169.80 to 179.79 |
| 13. | Quartzite | 2320 | 144.83 |
Also, read: 10 Types Of Stones Used For Construction Works
Unit Weight Wood
Timber or wood have been the most widely used construction materials. Some of the timber with their density are as follows.
| S.No. | Wood | Unit Weight | |
|---|---|---|---|
| Kg/m3 | lb/ft3 | ||
| 1. | Cypress | 515 | 32.00 |
| 2. | Black Siris (Kala Siris) | 760 | 47.40 |
| 3. | White Siris (Safed Siris) | 640 | 40.00 |
| 4. | Maple (Black) | 640 | 40.00 |
| 5. | Maple (White) | 755 | 33.00 |
| 6. | Oak | 730 | 45.55 |
| 7. | Indian Oak | 865 | 54.00 |
| 8. | Rubber Wood | 595 | 37.00 |
| 9. | |||
| 10. | Sal Wood | 990 | 61.77 |
| 11. | Sisso Wood | 770 | 48.00 |
| 12. | Spruce | 400 | 25.00 |
| 13. | Spruce (White, Black) | 432 | 27.00 |
| 14. | Teak | 655 | 40.90 |
| 15. | Walnut | 575 | 36.00 |
Also, read: Properties Of Good Timber As A Building Construction Materials
Unit Weight for Matels and Alloy
| S.No. | Metals and Alloy | Unit Weight | |
|---|---|---|---|
| Kg/m3 | lb/ft3 | ||
| 1. | Metals Only | ||
| 1.1 | Aluminum | 2739 | 169.72 |
| 1.2 | Copper | 8940 | 557.856 |
| 1.3 | Cast Iron | 7135 to 7250 | 449.467 to |
| 1.4 | Cobalt | 8746 | 545.75 |
| 1.5 | Lead | 11343 | 707.80 |
| 1.6 | Nickel | 8900 | 555.72 |
| 1.7 | Tin | 7280 | 454.27 |
| 1.8 | Tungsten | 19292 | 1204.41 |
| 1.9 | Zinc | 7135 | 445.224 |
| 2. | Alloy Only | ||
| 2.1 | Brass | 8580 | 535.68 |
| 2.2 | Bronze | 481.00 to 541.00 | |
| 2.3 | Galvanized Steel | 7850 | 557.856 |
| 2.4 | Steel/Mild Steel | 7850 | 489.84 |
| 2.5 | Stainless Steel | 7480 to 8000 | 466.75 |
Also, read: How To Calculate Unit Weight Of Steel Bar
References:
- The Wood Database. (2023, December 22). The Wood Database. https://www.wood-database.com/
- IS 399:1963. Classification of Commercial Timber and Their Zonal Distribution. Indian Standard. ISI. New Delhi 110002
