How to Reinforce a Concrete Slab: Fiber Reinforced Concrete

What You'll Need
Tape measure

Pouring out a concrete slab can seem fairly routine, but if you want to make your path work harder, then you need to reinforce concrete slabs with something else. While it is common for the slab to be reinforced with steel, the use of different types of fiber has also become very popular in recent years. You can find a range of different fibers, such as glass, but the most often used type of reinforced concrete slab fibers is the polymeric, or polyester, fiber. While you cannot use these in concrete slabs which are being used to span gaps, you can use these to support the slab by placing them inside the concrete mix. The use of fibers in concrete slabs can help you to avoid simple cracks and holes which can ruin the look of a path or patio.

Step 1 - Dig a Hole

Before you can begin laying your concrete slab, you will need to dig a hole large enough to support the slab. This should be around 2 inches deeper than the depth you intend for your slab, so that you can lay some gravel below it. This will help the fiber to reinforce the concrete, and will also keep the concrete undamaged and secure. Mark out the area to be dug with your pegs and some string, and then use the shovel to dig a hole. Add a layer of gravel. 

Step 2 - Reinforce the Sides

In order to properly shore up the sides of the concrete and fiber mix while it is drying, you will need to add a piece of wood for each of the sides that need to be covered. This will help you to keep the sides of the concrete even. Place the wood into the hole on top of the gravel, and secure it to the pegs with string.

Step 3 - Make the Concrete

Take your concrete mix, and pour it into the bucket. You should have the concrete slightly watered down, as this will help the fiber to mix completely with the concrete. Mix in fibers, a handful at a time, taking care not to allow the fibers to form clumps. The clumping of fibers will leave some parts of the concrete unreinforced, so stir well. If necessary, add a specialist wetting agent which can prevent the fibers from sticking together. You should make sure that there are sufficient fibers in the mix to produce reinforcement. Read your guidelines for details.

Step 4 - Pour the Concrete

When the fibers are completely mixed into the concrete, give it a final stir, and then pour it into the mold. Leave to set, taking care the that the fibers do not settle at the bottom. One way to prevent this is to pour the concrete in small layers at a time, allowing the slab to semi-harden between each layer.