Laying concrete blocks and paving stones is a common component of many landscaping projects. Building a concrete block wall or laying pavers for a patio or walkway is a great way to add curb appeal to your home.
First, mix the mortar. Mortar is the adhesive that holds the concrete blocks together. It is made from a mixture of cement, sand, and water. The ratio of cement to sand will vary depending on the type of mortar you are using. For most purposes, a ratio of 1:3 (one part cement to three parts sand) is sufficient.
Once the mortar is mixed, you can begin laying the concrete blocks. Start by laying out a level foundation for the wall or patio. This can be done using a string line and a level. Once the foundation is in place, you can begin laying the blocks. Apply a layer of mortar to the bottom of each block and then set it in place. Use a level to make sure that the block is level and that it is aligned with the other blocks.
Preparing the Concrete Blocks
Laying concrete blocks requires meticulous preparation to ensure a stable and durable structure. This section outlines the key steps involved in preparing concrete blocks before laying them down.
Cleaning the Blocks
Before laying concrete blocks, it’s essential to clean any dirt, debris, or efflorescence (white powder) from their surfaces. Efflorescence can hinder adhesion between the blocks and the mortar, compromising the strength of the wall. Use a stiff brush or a pressure washer to remove loose particles and stains.
Laying Out the Blocks Dry
Lay out the concrete blocks in their desired pattern on a level surface. This dry run allows you to visualize the final wall’s appearance and make any necessary adjustments to the block placement. You can also mark the locations of electrical conduits, plumbing pipes, and other openings at this stage.
Checking for Squareness and Leveling
Using a level and a square, check the corners of the dry-laid wall for squareness and level. This is crucial for ensuring that the wall will be plumb and straight. If any blocks are out of alignment, adjust their placement or shim below them as needed. Once the wall is square and level, number the blocks to facilitate easy reassembly.
Applying the Mortar
The first step in mortaring concrete blocks is to apply a base coat of mortar to the surface of the block. This base coat will help to seal the block and provide a surface for the mortar to adhere to. To apply the base coat, use a trowel to spread a thin layer of mortar over the surface of the block. Be sure to fill in any gaps or holes in the block.
Once the base coat has been applied, you can begin to apply the mortar in between the blocks. To do this, use a trowel to scoop up a handful of mortar and place it in the joint between the blocks. Use the trowel to spread the mortar evenly over the joint, filling in any gaps or holes.
Once the mortar has been applied, you can use a pointing tool or a trowel to smooth the surface of the mortar. This will help to improve the appearance of the mortar and make it more weather-resistant. Use a jointing tool to create a clean, finished look.
Here are some tips for applying mortar:
- Use a mortar mix that is specifically designed for concrete blocks.
- Apply the mortar in thin layers, and be sure to fill in any gaps or holes.
- Smooth the surface of the mortar after it has been applied.
- Allow the mortar to cure for at least 24 hours before applying any weight to it.
| Step | Description |
|---|---|
| 1 | Apply a base coat of mortar to the surface of the block. |
| 2 | Apply mortar in between the blocks. |
| 3 | Smooth the surface of the mortar. |
Laying the Concrete Blocks
Mark the First Course
Begin by outlining the perimeter of the wall with a mason’s line. Drive stakes at each corner and stretch the line taut. For the first course, snap a chalk line 2 inches above the footing or foundation to mark the block height.
Apply Mortar
Use a mortar box and trowel to mix mortar. Spread a layer of mortar on the footing or foundation, approximately 1/2 inch thick.
Position the First Block
Place the first block on the corner of the outlined perimeter, aligning it with the chalk line. Press down on the block to firmly embed it into the mortar.
Laying Subsequent Courses
Once the first course is laid, continue stacking blocks in courses, alternating the orientation of each course to create a staggered pattern. Spread a layer of mortar on top of each block before adding the next.
Filling Joints
As you lay blocks, fill the vertical and horizontal joints with additional mortar using a pointing trowel or a tuckpointer. This helps to seal the wall and prevent moisture penetration.
Tying Walls Together
To ensure stability, tie perpendicular walls together by overlapping blocks at the corners. Use metal ties or rebar embedded in the mortar to secure the walls.
Leveling
Periodically check the level of the blocks using a spirit level. If any blocks are uneven, adjust them by tapping them with a rubber mallet.
Curing
Allow the mortar to cure for a minimum of 24 hours before applying any weight or stress to the wall. Keep the wall moist by covering it with plastic or spraying it with water during the curing process.
Common Mistakes to Avoid
When working with concrete blocks, it’s essential to avoid common mistakes to ensure a strong and durable structure. Below are several pitfalls to watch out for:
1. Neglecting Proper Mortar Mix
Using an incorrect mortar mix ratio can weaken the bond between blocks. Ensure the mix adheres to the manufacturer’s specifications and is mixed thoroughly.
2. Improper Block Placement
Place blocks carefully to maintain a consistent level and avoid gaps. Use a level to check accuracy and tap blocks into place with a rubber mallet.
3. Overfilling Mortar Joints
Excess mortar can create weak points and hinder drainage. Apply mortar in a uniform thickness of approximately ½ inch, leaving a slightly indented joint.
4. Failing to Wet Blocks
Dry blocks absorb moisture from the mortar, weakening the bond. Wet the blocks thoroughly before laying them to ensure proper adhesion.
5. Overworking Mortar
Excessive mixing can reduce the mortar’s strength. Limit mixing time to what is necessary for a workable consistency.
6. Curing Issues
Proper curing is crucial for mortar to reach maximum strength. Keep the structure protected from rain and extreme temperatures for at least 24 hours.
7. Excessive Grout Force
Applying too much force when grouting can damage the joints. Use a grout bag or flexible tool to apply grout gently and avoid putting undue pressure on the joints.
| Mistake | Consequences |
|---|---|
| Neglecting Proper Mortar Mix | Weak bond between blocks |
| Improper Block Placement | Uneven surface and gaps |
| Overfilling Mortar Joints | Weak points and hindered drainage |
| Failing to Wet Blocks | Weakened bond due to moisture absorption |
| Overworking Mortar | Reduced mortar strength |
| Curing Issues | Incomplete mortar strength |
| Excessive Grout Force | Damaged joints |
Troubleshooting Mortar Problems
1. Mortar is too wet
Mortar that is too wet will be difficult to work with and will not adhere properly to the concrete blocks. It will also be more likely to sag and crack.
2. Mortar is too dry
Mortar that is too dry will be difficult to spread and will not fill the joints between the concrete blocks properly. It may also be more likely to crumble.
3. Mortar is not mixed properly
Mortar that is not mixed properly will not have the correct consistency and may not adhere properly to the concrete blocks.
4. Mortar is not the right type for the job
There are different types of mortar available for different applications. Using the wrong type of mortar can lead to problems such as cracking, spalling, and efflorescence.
5. Mortar is contaminated
Mortar that is contaminated with dirt, sand, or other materials can weaken the bond between the concrete blocks and the mortar.
6. Mortar is applied too thick
Mortar that is applied too thick can crack and spall. It can also make it difficult to level the concrete blocks.
7. Mortar is applied too thin
Mortar that is applied too thin will not fill the joints between the concrete blocks properly. It may also be more likely to crumble.
8. Mortar is not cured properly
Mortar needs to be cured properly in order to reach its full strength. Curing involves keeping the mortar moist for a period of time. If the mortar is not cured properly, it may be more likely to crack and spall.
9. Mortar is exposed to freezing temperatures
Mortar that is exposed to freezing temperatures can freeze and thaw, causing it to crack and spall.
10. Efflorescence
Efflorescence is a white or gray powder that can form on the surface of mortar. It is caused by the presence of soluble salts in the mortar. Efflorescence can be unsightly and can weaken the mortar over time.
How To Mortar Concrete Blocks
Mortaring concrete blocks is a relatively simple process, but it does require some care and precision. If you’re not careful, you can end up with a wall that’s weak or unstable. Here are the steps on how to mortar concrete blocks:
1. **Prepare the surface.** The first step is to prepare the surface where you’ll be laying the blocks. This means removing any debris or vegetation, and leveling the ground. You may also need to excavate a trench for the footing of the wall.
2. **Mix the mortar.** The next step is to mix the mortar. Mortar is a mixture of cement, sand, and water. The ratio of cement to sand will vary depending on the type of mortar you’re using. Once the mortar is mixed, it should be the consistency of peanut butter.
3. **Apply the mortar.** Once the mortar is mixed, you can begin applying it to the blocks. Use a trowel to spread a thin layer of mortar on the bottom of the block, and then place the block in position. Tap the block with a hammer to settle it into place.
4. **Level the blocks.** Once the blocks are in place, you need to level them. Use a level to check the blocks, and then adjust them as necessary. You can use a rubber mallet to tap the blocks into place.
5. **Fill the joints.** Once the blocks are level, you need to fill the joints between them with mortar. Use a pointing trowel to apply the mortar to the joints, and then smooth it out. The mortar should be flush with the surface of the blocks.
6. **Cure the mortar.** Once the mortar is applied, you need to allow it to cure. Curing is a process that allows the mortar to harden and gain strength. The curing time will vary depending on the type of mortar you’re using.
People Also Ask About How To Mortar Concrete Blocks
What is the best mortar mix for concrete blocks?
The best mortar mix for concrete blocks is a Type N mortar mix. This type of mortar is strong and durable, and it is easy to work with.
How thick should the mortar joints be?
The mortar joints between concrete blocks should be approximately 1/2 inch thick. This will provide a strong and durable bond between the blocks.
How long does it take for mortar to cure?
The curing time for mortar will vary depending on the type of mortar you’re using. However, most mortars will take at least 24 hours to cure completely.
