Sand lime bricks, also known as calcium silicate bricks, are a durable building material created through a specific manufacturing process.
The fundamental components of sand lime bricks are natural and readily available materials. As detailed in their production, these units are produced by mixing lime, sand, and water in a batch process. This simple blend forms the basis of the brick.
Key Ingredients
The main ingredients used to manufacture sand lime bricks include:
- Sand: Typically makes up the largest proportion of the mix, providing the structural body of the brick. High-silica content sand is preferred.
- Lime: Acts as the binder. It is usually either quicklime (calcium oxide) or hydrated lime (calcium hydroxide).
- Water: Essential for initiating the chemical reaction between the lime and sand.
During the manufacturing process, the lime must react immediately with the quicklime (if quicklime is used) upon mixing with the sand and water. This initial reaction is crucial to develop some early 'green' strength before the units undergo further processing, often involving high-pressure steam curing in an autoclave. This hydrothermal process facilitates the formation of calcium silicate hydrates, which bind the sand particles together, giving the brick its final strength and durability.
Typical Composition
While variations exist, a general idea of the proportion of materials in sand lime bricks can be seen below:
| Ingredient | Approximate Percentage by Weight |
|---|---|
| Sand | 88% - 93% |
| Lime | 7% - 12% |
| Water | (Added for reaction & workability) |
Unlike traditional fired clay bricks, sand lime bricks gain their strength from a chemical reaction between lime and silica under specific curing conditions, rather than high-temperature firing.
