Lightweight Concrete Blocks in Bangladesh: Everything You Should Know
Concrete block is gaining mass appeal in Bangladesh. Currently, the housing sector largely depends on traditional red bricks as the primary building block unit. However, numerous advantages of concrete blocks have persuaded many property owners to opt for concrete blocks. Integrating concrete blocks in building houses has made the process much easier and faster. Furthermore, concrete blocks have enabled the making of high-rise buildings. Among many types of concrete blocks, lightweight blocks are beneficial to build robust structures while keeping the overall weight of the building relatively lower than traditional brick-built structures. The popularity of lightweight concrete blocks in Bangladesh is also increasing.
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What is a Lightweight Concrete Block?
Lightweight concrete blocks weigh much less than solid blocks. Lightweight blocks are made from lightweight concrete. It is a blend of lightweight coarse aggregates like shale, clay, and slate, providing low density. Lightweight concrete’s density ranges from 1440 to 1840 kg/m3. The most crucial property of lightweight concrete is generated by introducing air into the concrete.
Lightweight concrete blocks are commonly AAC blocks (Autoclaved Aerated Concrete). AAC is lightweight precast foam concrete. AAC’s significant properties include lower density, porousness, reusability, non-toxicity, renewability, and recyclability. These blocks came into reality after a Swedish architect thought of an alternative to wood in 1924. Wood is beneficial in building houses due to its properties like thermal insulation, firm structure, and smooth workability while being lightweight. But wood has major disadvantages like combustibility, decay, and termite damage. AAC blocks have all the advantages of wood while being fire and termite resistant.
AAC blocks offer superior performance and durability. People opt for lightweight concrete blocks in Bangladesh as they are a more sustainable and better alternative to traditional red clay bricks. These blocks are eight to nine times the size of a traditional red brick and provide much better compressive strength. Furthermore, these blocks are three times lighter than red bricks.
Lightweight Block Specifications
Generally, AAC blocks have regular size dimensions that are 600mm in length and 200mm in height. The width can range between 75mm to 300mm. These blocks have compressive strength between 7.5 to 10 MPa. The block density ranges from 550 – 650 kg/m3. The fire resistance of the block largely depends on the thickness of the blocks. However, it can be fire resistant from 2 to 6 hours. Drying shrinkage is around 0.04%, and the sound reduction index is 45 DB for a 200mm thick wall. Per block weight can range from 6 to 20 kg.
Source: Civil Lead
Advantages of Lightweight Blocks in Bangladesh
Building with lightweight concrete blocks can provide various advantages over other options available. Here is a list of advantages:
Lightweight
The most crucial benefit of using lightweight AAC blocks is their lighter weight than other options. These are typically three to four times lighter. Furthermore, AAC blocks weigh almost 50% less than standard concrete masonry blocks. Constructing high-rise buildings provides a better solution in high-density population zones. So, more people can live inside one apartment complex. The usage of lightweight blocks is of paramount importance in high-rise buildings. They allow reducing the overall dead load of the building. Hence, taller buildings can be constructed with lightweight blocks.
Easier Workability and Aesthetics
Lightweight blocks are very easy to work with. Workers can maneuver the blocks to build structures without much hassle compared to other types of blocks. Due to their aerated concrete nature, they have more air voids. So, it becomes easier to handle these blocks even if they have high volumes. AAC blocks can be cut, drilled, nailed, and grooved to fit specific requirements. Custom-sized blocks are also available. Sometimes large construction projects require specific block sizes to adjust sanitary and electrical equipment. Lightweight blocks can be altered according to project requirements.
Better Construction Pace
The housing industry is booming in Bangladesh. In order to meet the demand of the influx of people in Dhaka, various construction projects are ongoing in places like Purbachal New Town. It is the most significant planned township in Bangladesh. There is supposed to be a provision of 26,000 residential plots of different sizes. It requires many building block units to build houses at such a scale. Lightweight concrete blocks can increase the pace of construction many times if the blocks are implemented.
Furthermore, different sizes of blocks reduce the number of joints in wall masonry. Lighter blocks facilitate faster construction and a more comfortable workspace. These blocks are easy to implement and harden quickly to set appropriately.
Minimum Wastage
Traditional red bricks increase the construction cost by a lot due to wastage. Clay bricks can break easily due to transportation or mishandling on construction sites. On the other hand, lightweight blocks have negligible breakage reporting less than 5%. Hence, the utilization rate of lightweight blocks is much higher, which increases work efficiency.
Thermal Insulation
Thermal insulation is one of the essential advantages of lightweight blocks. Lightweight blocks have tiny air pores inside them. It makes it an excellent insulating material. So, heat gets trapped inside during the winter seasons, and the insides remain calm during the summer season. As a result, air conditioning bills reduce by a large margin if homes are fitted with lightweight blocks.
Acoustic Performance
Another significant benefit of using lightweight blocks in Bangladesh is their sound isolation properties. Lightweight blocks have superior sound absorption properties due to the porous nature of the blocks, offering a sound attenuation of about 42 decibels. Significant cities in Bangladesh suffer from extreme noise pollution due to unregulated traffic and the malpractice of drivers. Car horns, bike horns, loudspeakers in streets, etc., create an extremely painful experience for city dwellers. Dhaka is one of the worst victims of sound pollution in the world. So, if your property is near a busy street, you must think about the consequences of noise pollution if your building does not incorporate sound-insulating materials. Lightweight blocks offer excellent performance in this regard by providing sound isolation.
Fire Resistance
Lightweight AAC blocks are non-combustible and fire-resistant. They can survive even at 1600 degrees Celsius for up to six hours, depending on the thickness of the wall. Lightweight blocks are extremely helpful in fire-hazard zones.
Cost Saving
Lightweight blocks can save a lot of cost during construction. The surface accuracy of lightweight blocks is very high, and as a result, the requirement for plaster is less. It can save up to 2.5% of the construction cost.
Lightweight blocks require less jointing and minimize the requirement for cement and steel. Different sizes of lightweight blocks help in increasing the carpet area. Furthermore, lightweight blocks do not require much repairing.
Due to their lightweight nature, these blocks are much easier to transport. It reduces the transportation cost and installation costs.
Earthquake Resistant
Lightweight blocks are excellent at absorbing seismic pressure waves. So, buildings can be much more resistant to earthquakes. The lightweight property provides outstanding steadiness of the core structure.
Accuracy in Shape
Lightweight blocks are very accurate in their shapes and sizes. These blocks offer exceptional smoothness on walls with perfect joints between different elements. It also reduces the use of mortars and offers more aesthetic values.
Pest Resistance
Lightweight blocks are made from inorganic materials. Therefore, pests or termites cannot attack the concrete block surface. It saves a lot of repairing costs due to damage and losses.
Reducing Water Consumption
Lightweight concrete blocks do not require any water curing. So, water consumption can be reduced where water is scarce. However, the mortar joints will still require water for curing.
Versatility and Longevity
Lightweight blocks reflect the urban nature of society. Modern and readily adaptable to different styles of architecture make it an attractive choice for many property owners.
Lightweight blocks are superior in terms of strength. Higher compressive strength gives the whole structure better durability and longevity. Lightweight concrete blocks do not get affected by harsh climatic conditions. Their degradation is negligible due to changing atmospheric conditions. Moreover, lightweight blocks resist chipping and cracking.
Moisture Resistance
Moisture can cause damage to the structure of the building. It is an essential issue in countries with higher rainfall like Bangladesh. Moisture protection is a primary concern in a building both from the inside and outside. Rainfall and water from soil are external sources of moisture. The internal source of moisture mainly comprises humidity. Lightweight blocks contain a very porous structure, commonly known as macropores. These pores are evenly distributed throughout the material. As a result, the absorption of water into the lightweight blocks is minimal.
Eco-friendly and Sustainability
People have become very aware of their impact on the environment. It is our responsibility to reduce our impact on the environment. Lightweight concrete blocks have the most negligible impact on the environment than other building blocks. They help reduce at least 50% of greenhouse emissions and decrease 30% of environmental waste.
Some Disadvantages of Lightweight Blocks
No product exists without its demerits. Lightweight blocks are no exception to that. Despite so many advantages, there are some factors you should consider before opting for lightweight blocks in your next construction project.
- Due to their lightweight nature, these blocks can only be used in partition walls. So, these cannot be used in load-bearing walls. Typically, solid and dense blocks are more suitable for load-bearing walls.
- Sometimes cracks can appear in lightweight blocks after installation if the proper method is not maintained.
- Lightweight blocks are brittle. So, they should be handled carefully.
- The cost per block is relatively higher than other alternatives. However, the overall construction cost reduces as installing lightweight blocks is cheaper due it requires less mortar, cement, and steel.
- To meet the demand for hanging requirements, long and thin screws should be used due to the brittle nature of lightweight concrete blocks. Large diameter wall plugs are more suitable than a standard plug, which costs a bit higher.
- Thicker lightweight blocks are more appropriate for establishing proper insulation in the home. Thicker blocks might increase the price of the construction process.
- Lightweight blocks cannot be hammered for chiseling services due to their brittle nature. However, these blocks can be cut easily by a carpenter’s saw, which is a time-consuming process that requires the help of professionals.
- If lightweight blocks are installed in high humidity environments, interior finishes must contain low vapor permeability, and exterior finishes require high permeability.
- Contractors are not familiar with the installation process of lightweight blocks.
Why Should You Choose Lightweight Concrete Blocks in Bangladesh?
As discussed earlier, there are many benefits of incorporating lightweight concrete blocks in construction projects in Bangladesh. So, it can make the process of building homes much easier and faster. Various properties of lightweight blocks are very suitable in Bangladeshi weather conditions. Large construction projects are already establishing the use of these blocks to make the lives of residents more comfortable.
Summary
There are many types of concrete blocks available in the Bangladeshi market. Property owners should ensure their homes are built with the most appropriate blocks to meet their budget and requirement. The Bangladeshi government is trying to phase out the use of red bricks as it poses severe threats to the environment. On the other hand, concrete blocks offer a more sustainable and eco-friendly solution. The use of lightweight blocks is becoming more appropriate in Bangladesh.
Frequently Asked Questions (FAQs)
Can I use lightweight concrete blocks in load-bearing walls?
Ans: No. It is not recommended to use lightweight concrete blocks in load-bearing walls.
Can I use lightweight blocks in external walls?
Ans: Lightweight blocks can be used in both internal and external walls in a non-load-bearing manner.
Are AAC blocks lightweight?
Ans: AAC blocks are recognized as lightweight concrete blocks.
Is it cheaper to build using red bricks or lightweight blocks?
Ans: Using lightweight blocks is around 20 – 25% cheaper than using red bricks.
Can I install tiles on lightweight concrete blocks?
Ans: Yes. You can use thin-set adhesive to install tiles on AAC/Lightweight concrete blocks.
