Preparing mortar involves combining masonry cement (or Portland cement and lime), sand, and water in the correct proportions to create a workable mixture for bricklaying, stonework, or other masonry projects. Here's a step-by-step guide:
1. Gather Your Materials and Tools:
- Masonry Cement (or Portland Cement and Lime): The binding agent. Choose the correct type for your project. Type N is common for general use.
- Sand: Use clean, sharp masonry sand. Avoid sand with high clay or organic content.
- Water: Clean, potable water.
- Mixing Container: A mortar box, wheelbarrow, or a mechanical mixer.
- Shovel or Hoe: For hand mixing.
- Trowel: For checking consistency.
- Gloves and Eye Protection: Safety first!
2. Determine the Correct Mix Ratio:
The ideal ratio depends on the type of mortar required and the manufacturer's recommendations. A common general-purpose mortar mix is:
- Masonry Cement Mix: 1 part masonry cement to 2 ¼ to 3 parts sand.
- Portland Cement and Lime Mix: 1 part Portland cement, ¼ to ½ part lime, and 2 ¼ to 3 parts sand.
Example using Portland Cement and Lime (ratios are by volume):
| Material | Volume |
|---|---|
| Portland Cement | 1 |
| Lime | 1/2 |
| Masonry Sand | 3 |
3. Dry Mixing:
- In your mixing container, combine the dry ingredients (cement, lime if using, and sand).
- Thoroughly mix the dry ingredients with a shovel or hoe until the mixture is a uniform color. This ensures even distribution of the binding agent.
4. Adding Water:
- Gradually add water to the dry mixture.
- Hand Mixing: Create a small well in the center of the dry mix and pour in some water. Fold the dry ingredients from the bottom of the container into the water. Mix continuously.
- Mechanical Mixing: Add water slowly while the mixer is running.
- Continue adding water until the mortar reaches a workable consistency. This is often described as "plastic" or "butter-like." It should be able to hold its shape on a trowel without being too stiff or too soupy.
5. Achieving the Right Consistency:
- The mortar should be easy to spread but not runny.
- Test the consistency by placing a small amount on your trowel and tilting it. The mortar should cling to the trowel and not slide off easily.
- If the mortar is too dry, add a little more water. If it's too wet, add a little more of the dry mix (cement and sand in the correct proportions).
6. Mixing Time:
- Mix the mortar for at least 5-7 minutes if using a mechanical mixer, or longer if mixing by hand, to ensure proper hydration and bonding.
7. Letting it Sit (Slaking/Hydration):
- Allow the mortar to sit for 10-15 minutes after mixing. This allows the cement to fully hydrate.
- Remix the mortar briefly before use to restore its workability.
8. Using the Mortar:
- Use the mortar within 2-3 hours of mixing. As mortar sits, it will begin to set.
- Do not add more water to mortar that has already begun to set. Instead, discard it.
Important Considerations:
- Weather Conditions: Hot, dry weather will cause mortar to dry out quickly. You may need to add more water during mixing and keep the mortar damp while working. Cold weather can slow down the setting process.
- Mix Consistency: Maintaining a consistent mix is crucial for uniform strength and appearance.
- Safety: Always wear gloves and eye protection when mixing mortar. Cement can irritate skin and eyes.
