Bricks are one of the primary building materials that give strength, durability, and versatility to construction. They are one of the oldest building materials that has been in use since 7500 BC. There are numerous bricks in the market, and each one has its unique characteristics, such as structure, strength, composition, looks, and budget.
In this blog, we will compare two of those bricks- Calcium Silicate Brick & Clay Brick discussing the key differences and where they can be used.
What are Calcium Silicate Bricks?
Calcium Silicate Bricks or Sand Lime Bricks are made by mixing sand, lime, and pigments in precise proportions under high pressure and temperature inside autoclave curing chambers.
They are factory-made bricks that need expensive equipment and constant supervision for manufacturing. These bricks have a sleek and uniform finish, with varying colour options. They are used for numerous applications in the construction field. They have high compressive and tensile strength and acoustic and durability properties.
What are Clay Bricks?
These are traditional bricks made of clay. The clay is processed and blended with aggregates in a homogenous mix before molding and then burnt in a kiln to add more strength and durability.
These are made completely eco-friendly Bricks or use large natural resources that pollute the environment. They have a long history and have been used widely over the years. The Class 1 burnt bricks have the highest quality and offer high strength and durability, which are suitable for multiple construction projects.
Key Differences Between Calcium Silicate Bricks and Clay Bricks
Both Calcium Silicate Bricks and Clay Bricks differ in terms of raw materials used, manufacturing process, strength, physical properties, usage, cost, and more. Here is a detailed comparison between the Calcium Silicate bricks and Clay Bricks.
Composition
| Calcium Silicate Bricks | Clay Bricks |
| Sand (Silica) is the primary raw material used that occupies 88-92% of brick’s weight. | Sand (Silica) is the primary raw material that occupies 50-60% of brick’s weight. |
| Lime is the secondary raw material that occupies 8-12% of the brick’s weight. | Clay (Alumina) is the secondary raw material that occupies 20% to 30% of brick’s weight. |
| Fly Ash (0.3-8%), Water (2-8%), and Pigments are added at the required quantity to help the calcium silica bricks attain their physical properties. | Lime (2-5%), Iron Oxide (5-7%), and Magnesia (<1%) are added to attain the cohesiveness, strength, and color of clay bricks. |
Manufacturing Process
Manufacturing of Sand-Clay Bricks
Sand, lime, fly ash, and coloring pigments are carefully chosen at appropriate proportions mixed with an adequate amount of water and moulded in a rotary table using a hydraulic press at a pressure ranging from 30 to 65 N/mm². The mold is transferred to the autoclave steel cylinders for curing under varying pressure and high temperature for 6 to 12 hours. This process induces a chemical reaction between sand and lime to form a crystal-like compound named Calcium hyposilicate. The autoclave steamed brick is unmoulded and tested before being transported to the construction site.
Manufacturing of Clay Bricks
The clay is processed through unsoiling, digging, cleaning, blending, weathering, and tampering by manually or mechanically mixing with water, sand, and other aggregates of appropriate proportion until the mixture attains the required moldable consistency. The clay is molded either using hands or powered compressing machines to avoid pore gaps.
The molded clay bricks are dried under the sun for days to weeks to months, depending on the climatic conditions and the type of bricks. The sun-dried bricks are placed under the sun for weeks to months, as it does not undergo the artificial burning process.
In burnt clay bricks, the bricks are dried for 3-10 days and are transferred to fire chambers or kilns under high temperatures of up to 1100℃ for 10 to 40 hours to attain maximum strength. The bricks are then tested and classified from First Class to Fourth Class bricks.
Strength and Durability
Resistance to Impact
Both Clay and Sand lime bricks have similar resistance to impact loads. However, it depends on the right composition and manufacturing methods. Both bricks can be engineered to withstand high-impact resistance by mixing aggregates and other additives before being molded.
Compressive Strength
Burnt Clay bricks have high compressive strength compared to sand-lime bricks, due to their compact, hard, and robust properties, which are induced by molding and kiln burning. Calcium Silicate bricks are loosely packed and are less resistant to compressive loads compared to clay bricks. The higher the density the stronger the bricks.
Thermal and Acoustic Insulation
Thermal Insulation
Clay bricks have higher thermal insulation properties compared to calcium silicate bricks. The burning process during the manufacturing of clay bricks induces the ability to withstand high temperatures. The clay bricks are ideally made for fireplaces and are used in the manufacturing of steel and fire kilns.
On the other hand, Calcium Silicate bricks comparatively have less resistance to heat, as they are loosely packed, which makes them less resistant to heat in the long run.
Acoustic Insulation
Calcium Silicate bricks have the highest acoustic insulations compared to clay bricks. The porosity of the sand-lime bricks prevents the external noise enter the building’s internal structure and is highly used for soundproofing. On the other hand, Clay bricks are packed more tightly, which makes the noises easily pass through the structure.
Cost Comparison
The clay bricks are more expensive compared to the calcium silicate bricks. The clay bricks are manufactured using more natural resources, manpower, and firing kilns, which makes them more expensive in comparison.
On the other hand, calcium silicate bricks are larger and could substitute more clay bricks in the construction, making it one of the ideal choices, if cost is a consideration.
Applications
Applications of Sand-Clay
These bricks are known for their resourceful applications in the construction field. They are used in multiple construction works for numerous purposes.
- These bricks are suitable for residential buildings for their insulation properties, which will keep the structure cool in dry and hot weather conditions.
- Using sand lime bricks in commercial structures has numerous advantages. These bricks can be used for the construction of walls, partitions, and other ornamental purposes.
- As Sand limes possess insulating properties, these bricks can be used in structures like schools, colleges, hospitals, and offices that require a noise-free environment.
Clay Bricks
- Clay bricks are commonly used to construct walls, foundations, structural elements, and decorative elements in residential, commercial, and industrial buildings.
- These are mainly made for fireplaces such as chimneys, steel factories, and other high-temperature places.
- They are also used to build cinema halls, theatres, schools, and hospitals, as their density helps in soundproofing and prevents noisy environments.
- The burnt bricks can also be used in retaining walls such as drainage, dams, raised beds, and borders.
Conclusion
Both clay bricks and calcium silicate bricks have unique characteristics that are suitable for different construction projects. Sand lime bricks are more modernized bricks that are ideal if aesthetics is the main consideration. On the other hand, clay bricks can withstand high loads and can be employed in load-bearing and engineered structures, making it one of the functional elements.