Forming Concrete Walls: Ep.17

Summary

This video details the process of building a retaining wall with concrete, focusing on the techniques and tools used in forming, rebar placement, and construction. It highlights the importance of attention to detail in material handling, using Simon's forms for efficiency, and ensuring structural integrity. The video also discusses safety measures, like proper scaffolding, and ways to control cracking in concrete. Aesthetic choices, such as reveal strips, and maintenance tips for forms, are also covered, demonstrating both the technical and creative aspects of construction.

Takeaways

• 😀 Stripping the forms is a labor-intensive but crucial task in construction, requiring careful staging to avoid duplicating steps and ensure efficiency.
• 😀 Cold joints, where two concrete pours don't bond together, are weak, but the rebar inside the structure provides the necessary strength.
• 😀 Forming materials, such as wood or Simon's hybrid steel-wood forms, are used to create concrete walls, with different types of forms offering varying levels of labor intensity and strength.
• 😀 Attention to detail is key when setting up forms to ensure they are plumb, square, and properly fastened, reducing future complications.
• 😀 Using form oil is essential to protect expensive forms from the concrete sticking and shortening their lifespan, but be careful not to oil the rebar, as it prevents concrete bonding.
• 😀 Rebar placement is vital, requiring meticulous attention to secure ties and ensure that the concrete forms correctly around the reinforcement.
• 😀 Concrete structures must be designed to control cracking, with provisions like reveal strips or chamfer edges that control where cracks occur.
• 😀 Decorative options for concrete walls include staining, sandblasting, or plastering, and these can be done either before or after the pour, depending on the desired look.
• 😀 The Simon's form system is fast and strong, allowing for larger concrete pours with fewer concerns about form failure during the pour.
• 😀 The use of scaffold brackets is a safety measure that ensures workers can easily and securely access high walls during the concrete pour without the risk of falling.
• 😀 The whole process, from form setup to stripping, is a well-organized sequence requiring the right tools and careful planning to ensure both structural integrity and worker safety.

Q & A

What is the process of 'stripping the forms' in construction?

Stripping the forms, also known as demolishing or wrecking the forms, is the process of removing the molds or templates used to shape concrete once it has set. It is important to perform this task carefully to avoid unnecessary handling of materials and ensure the forms are removed properly.

What is a cold joint, and why is it significant in concrete work?

A cold joint is the junction between two separate concrete pours that have occurred at different times, resulting in no bonding between the two layers. Cold joints are weak and can compromise structural integrity, but the presence of properly placed rebar can mitigate their impact.

Why is rebar so important in concrete walls?

Rebar is crucial because concrete has compressive strength but lacks tensile strength. Rebar reinforces concrete, providing the necessary strength to prevent cracking or breaking, especially under tension, such as the forces that may act on a retaining wall.

What are Simon's forms, and how do they benefit construction projects?

Simon's forms are a hybrid system combining steel and wood, designed to make concrete wall forming faster and more efficient. They are strong and versatile, allowing for taller concrete pours and a wide range of configurations, reducing the need for extra bracing and hardware.

What is the purpose of using form oil in concrete work?

Form oil is applied to the forms to prevent concrete from sticking to the mold, making it easier to strip the forms later. It also helps preserve the lifespan of the forms, ensuring they remain in good condition for future use.

Why is it crucial not to oil the rebar during concrete work?

Oiling the rebar can prevent the concrete from bonding to the rebar, which would compromise the tensile strength that the rebar provides to the concrete structure. Proper bonding between the concrete and rebar is essential for structural integrity.

What is the significance of tying rebar securely in concrete walls?

Tying rebar securely ensures that the reinforcement stays in place during the concrete pour, preventing it from shifting or dislodging. Properly tied rebar is essential to maintaining the structural strength and integrity of the wall.

How does the engineer specify the appearance and strength of the concrete wall?

The engineer specifies the concrete wall's structural characteristics, including the rebar placement and concrete mix. However, the appearance, such as the finish, texture, and whether it has decorative elements, is often up to the builder's discretion, with options like coloring, sandblasting, or exposing aggregates.

What are control joints, and how do they prevent cracking in concrete walls?

Control joints, such as reveal strips and chamfers, are intentional weak points designed to guide where the concrete will crack as it shrinks. This controlled cracking helps prevent random, unsightly fractures in the wall.

Why is it important to use scaffold brackets during wall forming?

Scaffold brackets allow workers to safely and efficiently access the top of a concrete wall during pouring and finishing. They prevent the danger of workers leaning on unstable ladders, ensuring a safe working environment and allowing for smoother, quicker work.