Buzz
When constructing a brick building, you'll save both time and money if you know the proper technique for mixing a high-quality mortar. The key is to mix the right amount so that the mortar doesn’t dry out and has the ideal consistency. Once you understand the proportions of the materials and the steps involved in mixing and using the mortar, you’ll be able to quickly prepare quality batches. Then you can just get started with the building process.
Steps
Learn the Formula
Measure 3 parts sand and 1 part cement for the mix. To create a standard mortar mixture, you need to mix sand and cement in a ratio of 3 parts sand to 1 part cement. If you’re using a full bag of cement, you’ll need three times as much sand, resulting in a larger batch of mortar. It’s recommended to mix only the amount you need.
- Measurements don’t need to be as precise as baking recipes. Typically, when mixing in large quantities, the sand is measured by the number of 'shovels full' per bag of cement, usually between 15 and 18 shovels, depending on the size of the shovel. It’s important to maintain the right ratio, but you can estimate by eye rather than measuring exactly.
Use the right amount of water. A bag of mortar requires about 12 liters of clean water to achieve the proper consistency. The amount of water needed depends significantly on the weather, the moisture level of the sand, and the type of mixture being used, so it’s important to carefully follow the instructions before adding water.
- Environmental conditions (temperature and humidity) will affect the mixture and need to be considered.
- Drier mixtures will have a stronger bond. Wetter mixtures may be easier to work with. This depends on your experience.
Use the correct amount of sand and cement. The best choice is fine, sharp sand for building, and it’s more effective to use a brand-new unopened bag of cement than an old one. Cement mixtures from brands like Quikrete, Sakrete, and others are suitable for construction.
- Some types come as pre-mixed mortar, meaning you don’t need to add sand. These are generally more expensive than Portland cement but are better for smaller projects. Check the label to see what’s needed. Even if sand isn’t required, the mixing process remains the same.
- Portland cement is not a brand name. It’s the name of the most common ingredient used in mixing mortar, concrete, and other binding compounds.
- Keep the dry sand and cement mixture as dry as possible. Materials will degrade if exposed to moisture. Only mix the amount needed, but try to use up all the dry mixture to avoid waste.
- Check the cement bag for lumps. Cement bags with clumps or hard blocks have been exposed to moisture, which will affect the bonding quality, and should be discarded.
- Different brands may provide slightly different mixing ratios. Always read and follow the instructions on the packaging. Generally, a 3:1 ratio works best and is effective.
Consider using lime as an additive. In areas where walls must withstand strong winds or other weather conditions, lime is often added to the mortar to increase its bond and stability. If you decide to add lime, you’ll need to adjust the sand ratio to maintain balance, creating a stronger, more adhesive mixture.
- If you plan to add lime, the appropriate ratio is 6 parts sand, 2 parts lime, and 1 part cement.
Remember that mortar with added lime sets faster. This means you will need to work more quickly or mix smaller batches of mortar.
Adjust the mixing formula based on the weather. In cold and damp climates, mortar will behave differently than in hot and dry areas. You may find that using less sand and more water is more effective in these conditions. You might need to experiment a few times to get the right mix and consistency.
- Generally, using mortar in mild and dry weather is easier than in cold and damp conditions. While it’s not always possible, you can learn to recognize the proper consistency and use the right amount of water.
The mortar should have the right consistency, sticking to the trowel when tilted at a 90-degree angle, but also wet enough to be easily worked with and poured into a bucket.
If working in cold conditions near freezing, consider adding more lime; in warmer weather, add more water to enhance the hydration reaction of the cement and speed up the setting process. Keep in mind that the finished product must be protected from freezing until it sets.
Mix a batch of mortar
Wet the mixing tools, wheelbarrow, and/or bucket. Before adding dry ingredients, make sure all tools that will come in contact with the mortar are wet, allowing it to slide out easily and minimize waste. Pour about half the required water into the mixer or tray, and add a small amount of water into the wheelbarrow or bucket holding the mortar.
- Depending on the job size, you can use a small mixing tray or a gasoline-powered mixer to handle larger batches. A mixer with multiple blades that can hold up to three 36 kg bags of dry mix will save you effort. You may also consider renting a mixer, especially for extended work periods.
Add the dry ingredients and start mixing. If using a mixer, start it so the blades gently mix the dry ingredients. Be careful not to throw ingredients into the machine, as it may cause splashing or damage the cement.
- The order of adding ingredients is not crucial, but many people add cement first, followed by sand if not using pre-mixed mortar. Typically, open the cement bag over the mixer, discard the bag, and scoop the required amount of sand into the mixer.
Turn away, wear respiratory protection, and avoid inhaling dust. Mortar mixtures containing silicates can cause chronic obstructive pulmonary disease or cancer.
Add water if necessary. When mixing mortar, or when the mortar mixer is running, pay attention to the consistency of the mixture. If it's too dry, add a small amount of water to keep it workable and moist. Be careful not to add too much water, as the mixture will become too loose, fail to bind, and be useless.
Mixing mortar by hand
Pile up some sand and place the corresponding number of cement bags beside the sand pile. The sand mound will resemble a small hill.
Cut one end of the cement bag and use the edge of the trowel to pry it open. Lift and pull the bag to pour out the cement.
Use a small trowel or shovel to mix quickly, ensuring the mixture is evenly distributed and has a consistent color. If the mixture is not evenly distributed, the mortar will not have the proper consistency.
Create a "volcano crater" and pour water into it. The water will start to settle and seep through the mixture.
Use a trowel or shovel to scrape the dry mixture from the edges into the center of the water hole. Continue adding the necessary amount of water, ensuring the mixture remains smooth and moist. Mix thoroughly to evenly distribute the ingredients.
Mix for about 3-5 minutes and let it sit for another minute. Some brands, like Quikrete, recommend letting the material absorb moisture for a moment, enhancing the mixture's effectiveness. It is important not to wait too long, as the mixture will harden. Similarly, overmixing will dry out the mixture and reduce the mortar's working time.
- A useful method to test the consistency is by "flipping" the trowel. Scoop some mortar onto the trowel, shake your wrist to spread it evenly, then flip the trowel at a 90-degree angle. If the mortar stays on the trowel without sliding off, the mixture is well-prepared.
Using the mortar
Start building. Check the consistency of the mortar and transfer it into a wheelbarrow or individual buckets, then pour it into the trough and begin construction. Ensure all tools are wet before use to prevent the mortar from sticking. If done correctly, the mortar should slide off easily.
Always wear protective gear when working with mortar. Dry concrete can cause irritation and is dangerous if it gets into your eyes, lungs, or on your hands. It's essential to wear gloves when handling mortar, as well as safety goggles and a mask when mixing dry cement. Cement particles can fly into the face and are harmful to the lungs. Be cautious and always have the necessary protective equipment.
Occasionally add a bit of water. Mortar tends to dry quickly, which is one reason it is so effective and easy to work with. You'll need to act quickly to keep up. After a while, the mortar in the trough will begin to dry, at which point you can slowly pour in a small cup of water and mix it with the trowel to maintain the proper consistency.
- If the mortar is too dry, the wall you build will be weak, and this can be particularly problematic when working on the foundation. It's crucial to keep the mortar moist and workable for optimal results.
Never mix more mortar than you can use within two hours. Mortar will often become too dry and unusable even if you add water. Plan your work carefully and only mix enough mortar for immediate use, as any leftover mortar will not be usable later.
- If you add lime to the mortar and can't work quickly enough, or if it's your first time building a wall, consider mixing smaller batches that can be used within 45-60 minutes.
- If possible, you may want to have someone mix the mortar and bring it to you.
Clean the mixer and all tools at the end of the day. After a long day of work, there's still one important task: tap all the hard and dry mortar off the mixer, trough, wheelbarrow, and other tools. There are various methods to do this, but the simplest and most effective is to use a hammer to tap the tools, gather the dry mortar, and dispose of it properly.
- Don't forget to clean your tools. An electric mortar mixer may struggle to work if dry cement is not cleaned off. If you mixed the mortar properly, there shouldn't be much dry cement to clean, but there will still be some.
It's better to mix a smaller batch of mortar and then mix another small batch rather than let excess material harden on your tools or form a large, solid block that you'll have to clean up.
Tip
- The wall with a white layer resembling salt after construction is often due to rapid drying. This can weaken the structure. To slow down the drying process and improve strength and longevity, cover the wall with wet cloths or tarps for a day or two.
- Pour water into the bucket before adding the mortar to avoid the hassle of digging to the bottom of the bucket to mix.
Warning
- Be cautious and protect your eyes when working with sand, lime, and cement because dust from dry cement and lime is highly toxic, and the mixer could splash the mixture out while running. You should wear safety goggles.
- Use a respirator mask. These can be purchased at paint supply stores. Cement has an alkaline pH, which can burn your sinuses and lungs. Be cautious and take preventive measures to avoid health issues. Wind can also help carry the dust away from you during mixing.
What You Need
- Sand
- Hydrated Lime
- Cement
- Water
- Bucket
- Cement Mixer
