The primary difference between mortar and a simple sand and cement mix lies in their composition, purpose, and resulting properties. Mortar typically contains lime and is designed for bonding masonry units, while a sand and cement mix (without lime) is often used as a component within concrete or for patching and rendering.
Here's a breakdown of the key distinctions:
Composition
| Material | Ingredients | Purpose |
|---|---|---|
| Mortar | Cement, fine sand, lime, and water | Bonding bricks, stones, and other masonry units |
| Sand & Cement Mix | Cement, sand, and water | Component of concrete, patching, rendering |
- Cement: Acts as the binding agent in both mixtures.
- Sand: Provides bulk and reduces shrinkage. Fine sand is generally used in mortar.
- Lime: Adds plasticity, workability, and water retention to mortar. Crucially, it is usually present in mortar but absent in a basic sand and cement mix.
- Water: Activates the cement and provides a workable consistency.
Purpose
- Mortar: Primarily used to bind together bricks, stones, and other masonry units in walls, foundations, and other structures. Its flexibility is key to accommodating minor movements in the building.
- Sand and Cement Mix: Used for various applications, including:
- Concrete Production: When combined with aggregates like gravel or crushed stone, it forms concrete.
- Patching and Repair: Filling cracks or damaged areas in concrete or masonry.
- Rendering: Creating a smooth or textured coating on walls.
Properties
- Mortar:
- Workability: Lime provides excellent workability, making it easier to spread and adhere to masonry units.
- Flexibility: More flexible than a pure sand and cement mix, allowing it to accommodate movement without cracking.
- Water Retention: Lime helps retain water, allowing the cement to hydrate properly and develop strength.
- Bond Strength: Designed for good adhesion to masonry units.
- Sand and Cement Mix:
- Hardness: Generally harder and less flexible than mortar.
- Strength: Can achieve higher compressive strength than mortar, especially when part of a concrete mix.
- Less Workable: More difficult to spread and work with compared to mortar containing lime.
- Potential for Cracking: More prone to cracking if used as a mortar substitute due to its lack of flexibility.
In Summary
Mortar is specifically formulated with lime to bond masonry units effectively, providing workability, flexibility, and water retention. A sand and cement mix lacks these properties, making it more suitable as a component of concrete or for patching and rendering, where high bonding to masonry isn't the primary requirement. Therefore, while a sand and cement mix can superficially look like mortar ingredients, the presence of lime in true mortar makes a significant difference.
