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How to tamp concrete
Build a formwork for your concrete surface.
Before you begin tamping or even pouring the concrete, you'll need to have forms in place. Nail together a series of boards to fit the area you'll be concreting, dividing the different sections as needed.

Select from:
1). Trace the lines of the forms together using a landscape ruler or pencil to create the trowel lines. Polyurethane or kevlar is a weak material, but for concrete that's not waterproof, use a moisture-retaining compound like sandstone.;
2). You can find formwork templates at a hardware store or online. Break the concrete into blocks and joints.;
3). When you run out of boards, lay a tarp down to protect the concrete rather than covering it completely. Use drywall screws to secure your forms in place.;
4). Use a level to make sure the surface comes out perfectly flat. Formwork structures serve to mark the perimeter of the concrete surface and contain the wet concrete mix while it's being spread and compacted.;
4).