This is courtesy of poolcenter.com.
The first section details with concrete repairs, and is followed by plaster repairs.
Concrete Swimming Pool Repair
As your gunite or concrete pool begins to age, the plaster will require the occasional repair. Cracking, hollow spots, sometimes called â€œpop-upsâ€, and chipping are not uncommon. As are wear spots in your pool plaster, when the plaster is worn away, and the gunite below the plaster is showing. Most of these pool plaster repairs can be done by you. With the right tools, the right materials, and a little know how, you can repair most small cracks and chips without too much effort. The following is a step by step guide to making typical pool plaster repairs.
Swimming Pool Crack Repair
Cut the crack out 1/2â€ deep and extend the length of the crack one inch on both ends. You will need a grinder or saw with a diamond blade. You can rent a 4â€ grinder, or buy one for about $50.00. Be sure to use all of the proper safety equipment and safe operating procedures.
Allow the crack to dry and wipe away all dust and debris.
Apply a bead of caulk along the length of the crack leaving 1/4â€ space to allow for plaster to cover the caulk.
Allow the caulk to dry.
Mix some pool patch or white Portland cement and white sand with water and an acrylic cement bonding agent (available at most home improvement super centers). The mix should be the consistency of loose peanut butter.
Lightly moisten the surface. With a flat trowel or putty knife, apply your pool patching mixture to the crack. Gently push the mix into the crack to make sure there is no air left in the gap.
Smooth and even out the patch area with your trowel, and sponge the new patch to match the consistency of the existing surface. If the pool plaster repair wonâ€™t be under water for more than a few hours, cover it with a wet towel to keep it moist until the pool repair is covered with water to prevent the job from cracking.
Fill the pool as soon as possible and go swimming!
Swimming Pool Plaster Repair
Get your hammer and chisel and remove any loose plaster that is not bonded to the pool surface. Drag the floor of the pool with a heavy chain and listen for hollow spots, or tap the pool floor with a hammer. You will be able to hear the hollow pool plaster. Chip them up. Be sure to use eye protection, gloves and all of the proper safety equipment.
Chisel some divots and pock marks into the surface that will be patched to help your new plaster patch bond to the existing surface. Acid rinse the surface to be repaired.
Figure out the surface area to be patched. Mix your pool patch or a mixture of 1/3 white Portland cement and 2/3 white sand. If the plaster is a custom color (grey, black) you will need to add cement dye.
Mix the plaster mix and some acrylic bonding agent together with water. Mix to the consistency of peanut butter.
The best way to apply the mix is with a â€œpool trowelâ€. Wet the surface with your sponge or a fine mist.
Apply the plaster mix with your trowel. Push the mixture into the corners and divots. Make sure you trowel it enough to there are no air bubbles left in the mixture. Trowel patch smooth. Wait 15 minutes and trowel the patch smooth again, you may need to sprinkle a little water around the edges to smooth it in with the existing plaster. Be sure to keep the pool repair moist until it is under water.
Fill your newly patched swimming pool immediately.