Vibrate Form to Remove Air Bubbles

What happens here

Once the concrete is leveled, the most critical step for a smooth finish is to remove air bubbles. This is achieved by vibrating the formwork. The presenter demonstrates using a reciprocating saw without a blade attached, pressing the side of the tool against the exterior of the plywood formwork. The vibrations cause trapped air bubbles within the concrete to rise to the surface. An orbital sander can also be used for this purpose, as its vibrations are effective. Continue vibrating all sides of the form until no more air bubbles appear, ensuring a dense and structurally sound concrete slab. It's important not to over-vibrate, but also not to miss any spots, as any remaining air pockets will result in imperfections (bug holes) on the finished surface that may need patching with Portland cement or similar material.

Goal: To achieve a dense, void-free concrete surface, vibrate the formwork using a reciprocating saw or orbital sander to release trapped air bubbles.