A concrete crack can occur when concrete has not been properly cured or allowed to set. This could be noticeable in a swimming pool, as well as other surface areas that are made from concrete. To prevent pool concrete from cracking, the following steps should be taken when preparing and laying concrete.
Step 1 - Prepare the Pool Area
The area that you select for the pool should be level and compacted to prevent an uneven pour. Uneven levels will cause shifting that will lead to cracks in the concrete. Use a manual hand soil compactor or rent a compactor from an equipment leasing store to compact the soil. A level should also be used to determine how level the soil is after compacting.
Step 2 - Prepare the Concrete Mix
Read the instructions thoroughly and understand how to correctly prepare the concrete mix. Water is added to the mix to allow the concrete to be spread over the pool surface. Water, as it evaporates, causes the concrete mix to dry and become hard. Resist simply adding more water since the ratio of water to concrete mix will be incorrect. This will result in too little concrete being poured and lead to eventual cracking.
Consider renting a mixer or some machine that will mix and dispense the concrete for you quickly before it sets.
Step 3 - Cutting Control Joints in the Slab
A control joint is a cut in the slab that allows for the expansion of the concrete over time. A control joint should have the depth of the slab and be set at a ratio of one to three of the slab’s thickness. A 4-inch thick concrete slab should have control joints sets every 12 inches or one foot. A saw can be used to cut the control joints and they should be set before the concrete cures completely.
Step 4 - Allow the Concrete to Cure
After the control joints have been cut, you should water the slab constantly over time to make sure it cures properly. If the concrete does not cure, it will crack. Spraying water keeps the slab moist and allows it to come together perfectly without cracking or splitting.
The concrete can be cured by covering the slab with sand. The sand should be applied after the control joints have been cut and watered.
Step 5 - Protect the Slab with a Seal Overnight
Place a waterproof paper sheet or a plastic seal over the concrete to further allow it to cure and dry. This will protect the surface and permit drying to occur evenly and completely.
Step 6 - Apply a Chemical Membrane
A chemical membrane cure, which can be purchased from the hardware store, should be applied to the concrete. The curing is the final step that prepares the concrete for use in the pool.