The choice of construction materials in the building sector greatly affects the safety, cost of the project, plus its role in environmental sustainability, among other elements. Among the most commonly used materials as building blocks are red bricks and cement concrete blocks. Their differing physical and mechanical characteristics give each material its own benefits, resulting in broad usage across multiple sectors. This article unpacks the various aspects of these materials, along with their properties and suitability for various construction applications.
Understanding the Core Materials
What are Traditional Red Bricks?
Red bricks, commonly referred to as traditional bricks, are created by shaping clay, water, and aggregates and firing it in kilns under intense heat. This method produces bricks with a distinctive red color and great durability. Red bricks have been used in the building and construction industry for a very long time and are still used almost everywhere because of their beautiful appearance and durability.
Types of Bricks
1. Unburnt or Sun-Dried Bricks
The bricks of this type are made by letting the clay dry in the sun. They are not as strong as burnt bricks and thus only temporary structures are normally made of them.
2. Burnt Clay Bricks
The bricks fired in kilns are much stronger; thus, they are used for permanent constructions most widely. Burnt clay bricks are of the following types:
- First Class Bricks: With the topmost quality, size, and colour, first-class bricks are free of cracks and very uniform. They are used to make load-bearing walls, external walls, arches, and in reinforced brickwork.
- Second Class Bricks: They are not so uniform and may have tiny cracks. They can be used in partition walls, plastering, and internal structures.
- Third Class Bricks: They are not regular in shape, and not very great in terms of strength, however, third-class bricks can be used in areas with no rainfall or for temporary structures.
- Fourth Class Bricks: With low strength, they are mainly used as aggregates in concrete.
What are Cement Concrete Blocks?
Cement concrete blocks are commonly referred to as concrete masonry units (CMUs). They are essentially made by mixing cement, sand, and gravel with water and then pouring this mixture into molds and allowing it to harden, so as to get solid or hollow blocks. These blocks are specially designed to be used in the construction of load-bearing walls and other structural applications, where they offer the advantage of easy use and adaptability in the building process.
Types of Concrete Blocks
Concrete blocks are available in two basic kinds,
1. Solid Concrete Blocks
These solid blocks consist of more than 75% concrete and are thus almost twice the weight of hollow blocks. Consequently, they are energy-efficient in use in elements such as walls, foundations, retaining walls, chimneys, and other heavy constructions in which the strength and stability are required to be high.
2. Hollow Concrete Blocks
Since about half to seventy percent of the volume is empty, hollow concrete blocks are lighter and can be easily handled. These blocks are still strong and are often used in building high-rise walls, fences, and other dividing structures. However, they are not as strong as solid blocks and generally not used to build load-bearing structures.
At present, concrete blocks, especially hollow ones, are considered a preferred material in the building sector because of their low price, easy handling, and time-saving installation. The blocks can even be designed as load-bearing walls, which gives them great potential for modern construction works of various types.
Head-to-Head Comparison: Red Bricks Vs. Cement Blocks
Compressive and Tensile Strength
Red Bricks provide good strength under compression. However, compared to cement blocks, they are brittle. They are robust and compact, but the density of these bricks lowers their tensile strength, which makes them prone to developing surface cracks quickly. This brittleness may also cause them to break in the process of transportation.
Cement Blocks excel over red bricks in both compressive and tensile strength. They can bear very high compressive pressure, hence they are the right choice for high-rise and heavy-load constructions. Moreover, the correct design of their tensile strength minimises breakage during transport and construction, thus large-scale projects are safer and more efficient.
Thermal and Sound Insulation
Red Bricks: The small holes in the structure of red bricks give them high thermal resistance properties, which in turn help in keeping the temperature inside the building stable. Moreover, they can also be used as a source of good sound isolation.
Cement Blocks: Compared to red bricks, cement blocks are less efficient in building insulation. However, if the blocks are hollow, then they can provide better temperature insulation. The noise isolation depends on the type of block and the method of construction.
Size, Uniformity, and Finish
Red Bricks
Bricks and blocks in India come in multiple different standard sizes, and each one is designed for use in different construction works.
Sizes of bricks
- Modular/Metric Bricks: 190 x 90 x 90 mm (machine-made, widely used in construction).
- Non-Modular Bricks: 230 x 110 x 70 mm (size is a bit bigger than Modular bricks and these are used in traditional construction).
- Traditional Bricks: 230 x 150 x 75mm (they were commonly used in buildings that are very old, but are still widely used today).
Burnt Clay Bricks: Standard size: 190 x 90 x 90 mm, size with mortar: 200 x 100 x 100 mm.
Brick Classifications
- First Class Brick: The characteristics of this type of brick are: uniform colour, thoroughly burnt, water absorption less than 10%, crushing strength of 280 kg/cm², and use in structures that are resistant to corrosion and will last for a long time.
- Second Class Brick: Over-burnt a little, water absorption 10-15% strength 175 kg/cm², these kinds of bricks are ideal for the construction of houses of low height and projects of a temporary nature.
- Third Class Brick: The bricks look like they are in no standard shape or size, water absorption is between 15% and 20%, their strength is 140 kg/cm², and are only used for the construction of non-load-bearing walls and walls of a temporary nature.
Bricks must have a weight that is no more than 3 kg so that they can be handled without any difficulty.
Cement Blocks
Concrete blocks are made with different dimensions to allow for some degree of flexibility during building. As stated by BIS (Bureau of Indian Standards), their standard nominal dimensions would be,
- Length: 600, 500, 450, or 400 mm
- Height: 100 or 200 mm
- Width: 50, 75, 100, 150, 200, 250, or 300 mm
The machine-made concrete blocks offer a higher degree of accuracy than the hand-made ones, thus making the sizes consistent. For load-bearing walls, blocks of 200 mm width are used, while those of 100 mm width are suitable for parapets or filler walls.
Water Absorption and Dampness
- Red Bricks: Due to their high water absorption rate, bricks can retain moisture internally, leading to the appearance of salt on their surface. This can cause corrosion of metal elements, ultimately reducing the lifespan of the house. Unless made specially for being left exposed (machine-made exposed bricks of first-class quality), they need coatings of plaster and paint to resist water.
- Cement Blocks: The lower water absorption rate makes cement blocks a better choice for areas where moisture is a problem; hence, the structure’s durability is increased. However, they also need moisture-resistant coatings like plaster or paint in most cases.
Speed of Construction and Labour Requirement
- Red Bricks: The small size and the irregularities of red bricks are such that they can slow down the construction process, whereby more labour will be required for the handling and placement of bricks.
- Cement Blocks: Large sizes and standards allow the construction to be done in less time and with less labour. This will lead to the money that can be saved being used for other purposes.
Cost and Environmental Analysis
Per-Unit Cost and Mortar Consumption
Red Bricks
Red bricks are being sold at a price of ₹5 to ₹15 per brick. First-class bricks that are used for exposed applications may cost much more. The bricks are very cheap in general, but the initial construction cost rises with the high requirement of mortar (since brick size is low, more mortar as well as a larger number of total bricks are needed) for the total construction.
Concrete Blocks
AAC Blocks AAC blocks are lightweight and have good insulation. Their price is ₹3200 to ₹3500 per cubic meter, or ₹80 per block.
Solid Concrete Blocks
- 4-inch: ₹22 – ₹32
- 6-inch: ₹33 – ₹53
- 8-inch: ₹54 – ₹73
Hollow Concrete Blocks
- 4-inch: ₹29 – ₹37
- 6-inch: ₹38 – ₹65
- 8-inch: ₹66 – ₹103
Concrete blocks can be of different sizes and types; as a result, they offer a large price range to cater to different kinds of construction.
Overall Project Cost Implications
By including labour cost, material efficiency, and construction duration, one could end up with big savings by using cement blocks.
Carbon Footprint and Sustainability
Although red bricks have natural components, their manufacturing process is ranked as a major source of energy consumption along with the emission of pollutants; hence, red bricks have a heavy toll on the environment. Cement blocks become a better option for the environment, especially if they are made with the support of fly ash or some other recycled materials.
Final Verdict: Which One Should You Choose?
When to Opt for Bricks?
- Aesthetic Considerations: In cases where the beauty of the building is the primary concern, like in heritage buildings or decorative facades, red bricks are able to give a lovely and timeless look.
- Thermal Insulation Needs: While living in a place where the weather is either too hot or too cold, the use of red bricks with their excellent thermal insulation properties can go a long way in saving energy.
When to Opt for Cement Blocks?
- Structural Requirements: Choosing cement blocks for the building of load-bearing walls and large-scale constructions is the best way to ensure the structure gets the required strength and stability.
- Cost and Time Efficiency: If the goal of a project is to reach its completion faster and at a lower labor cost, then the employment of cement blocks will be an ideal move.
Conclusion
Both red bricks and cement concrete blocks are good in their own ways and are ideal for solving different construction problems. What to choose between them should be a decision that reflects structural needs, aesthetic tastes, environmental concerns, and financial limitations. The right building material can be selected not only to complete but also to extend the life of the construction work by deeply addressing such issues as these.
Apoorva H P Achar