Joining concrete blocks primarily involves using mortar to create strong and stable walls or structures. Here's a breakdown of the process:
1. Preparation is Key:
- Ensure a Solid Foundation: The foundation must be level and capable of supporting the weight of the concrete block structure.
- Gather Materials: You'll need concrete blocks, mortar mix, water, a trowel, a level, a masonry saw (for cutting blocks), a joint filler/striker, and safety glasses.
- Mix the Mortar: Follow the manufacturer's instructions to mix the mortar to the correct consistency. It should be workable but not too wet or runny.
2. Laying the First Course (Row):
- Create a Mortar Bed: Apply a generous layer of mortar (around 1 inch thick) along the foundation where the first course of blocks will sit.
- Position the Corner Blocks: Carefully place the corner blocks into the mortar bed. Use a level to ensure they are perfectly level both horizontally and vertically. These corner blocks will serve as guides for the rest of the course.
- Lay the Remaining Blocks: Apply mortar to the head joint (vertical edge) of each block and press it down into the mortar bed. Slide the block into position against the previously laid block.
- Maintain Consistent Joints: Aim for mortar joints that are approximately 3/8 of an inch (10 millimeters) thick. Use a trowel to remove excess mortar.
3. Subsequent Courses:
- Overlap the Joints: Stagger the joints between courses for added strength. This is typically done by using a half-block at the start of alternating courses.
- Apply Mortar: Apply mortar to the top of the previous course (bed joint) and to the head joint of the block you're laying.
- Set the Block: Carefully lower the block into position, ensuring it is level and plumb.
- Tool the Joints: Once the mortar has begun to set (but is still pliable), use a joint filler or striker to create a smooth, consistent finish. This compresses the mortar and improves its weather resistance.
- Remove Excess Mortar: Clean off any excess mortar from the block faces with a trowel.
4. Important Considerations:
- Use a Level Regularly: Continuously check for level and plumb as you lay each course.
- Curing: Keep the mortar moist for several days after laying the blocks to allow it to cure properly.
- Reinforcement: For taller walls or structures, consider using rebar (reinforcing steel bars) embedded in the mortar joints for added strength.
- Safety: Always wear safety glasses when working with concrete blocks and mortar.
In summary, joining concrete blocks involves creating a mortar bed and head joints, carefully positioning the blocks, maintaining consistent joint thickness, staggering the joints, and ensuring the structure is level and plumb throughout the process.
