Mixing brick mortar involves combining cement, lime, sand, and water to create a workable paste with a toothpaste-like consistency, suitable for laying bricks.
While the provided reference is limited, here's a more comprehensive guide to mixing brick mortar:
1. Gather Your Materials:
- Portland Cement: Provides strength and bonding.
- Hydrated Lime: Improves workability and water retention.
- Sand: Provides bulk and reduces shrinkage. Use mortar sand (also called masonry sand), which is a graded, clean sand.
- Water: Clean, potable water is essential for hydration.
- Mortar Mix/Pre-blended Mix (Optional): Simplifies the process, ensuring proper ratios if you're a beginner. These usually just require adding water.
2. Determine the Correct Ratio:
The ideal mortar mix ratio depends on the type of mortar you need for your specific project. Here are some common ratios (cement:lime:sand):
- Type N (General Purpose): 1:1:6
- Type S (High Strength): 1:0:3 (or 2:1:9)
- Type M (High Strength, Heavy Loads): 1:0.25:3
Always consult local building codes and the manufacturer's recommendations for the appropriate mortar type for your project.
3. Mixing the Mortar (By Hand):
a. Dry Mix: In a mortar box or wheelbarrow, thoroughly mix the dry ingredients (cement, lime, and sand) until the mixture is a consistent color. This step is crucial for even distribution.
b. Add Water Gradually: Create a well in the center of the dry mix and slowly add water. Use a shovel or hoe to incorporate the water into the dry ingredients, working from the outside in.
c. Mix to Consistency: Continue adding water and mixing until the mortar reaches a plastic, workable consistency similar to toothpaste. It should stick to your trowel but not be too runny. The "toothbrush test" mentioned in the reference is a simple way to visualize this.
d. Let it Slake (Optional): Allow the mortar to slake (rest) for 10-15 minutes. This allows the lime to fully hydrate, improving workability. Add a little more water after slaking if needed, to restore the toothpaste consistency.
4. Mixing the Mortar (Using a Mortar Mixer):
a. Add Water: Pour a portion of the water into the mixer.
b. Add Dry Ingredients: Gradually add the dry ingredients (cement, lime, and sand) while the mixer is running. Avoid adding the entire amount at once, as this can cause clumping.
c. Mix to Consistency: Continue adding water until the mortar reaches the desired consistency.
d. Mixing Time: Mix for at least 5 minutes to ensure thorough blending.
5. Testing the Consistency:
- Trowel Test: Scoop up some mortar with a trowel and turn the trowel upside down. The mortar should cling to the trowel without falling off immediately.
- Thumb Test: Press your thumb into the mortar. It should leave a slight indentation without being too soft or crumbly.
Important Considerations:
- Safety: Always wear safety glasses, gloves, and a dust mask when mixing mortar, as cement and lime can be irritating to the skin and lungs.
- Weather: Avoid mixing mortar in extreme temperatures (below freezing or above 90°F), as this can affect the curing process.
- Cleanliness: Keep your tools and mixing area clean to prevent contamination.
- Batch Size: Mix only as much mortar as you can use within a couple of hours, as it will start to harden. You can re-temper mortar by adding water and remixing it, but only do this within a limited time frame. Mortar that has started to set should be discarded.
- Premixed Mortar: Consider using a premixed mortar. These just require the addition of water, ensuring the correct ratios and simplifying the process.
By following these steps, you can effectively mix brick mortar and achieve the desired consistency for your masonry project.
