Swimming pools that are built into the ground are often made from a mixture that includes cement. A gunite swimming pool is created by mixing cement, sand and water together then spraying the combination onto the surface using pneumatic pressure. It is held onto the surface by a frame created out of rebar. Together the rebar frame along with the gunite mixture is what creates the base of the pools structure. A plaster surface, often referred to as marcite is added to finish the pool.
Plaster creates a waterproof barrier that gunite alone does not have. The pools plaster should be applied by a team of professionals to guarantee that plaster surface is thick enough that it does not allow water to seep out. If the plaster is not thick enough the entire pool will need to be drained to repair the plaster hence stopping the water loss the pool is experiencing. This is a hassle that homeowners can avoid by hiring a reputable pool plastering company.
One piece of advice I like to give new pool owners, especially those with gunite pools is to never drain your pool without first having professional instruction or hiring a company to help. A pool is not drained properly can end up with extensive damage to the pools surface, plumbing and surrounding area.
Cracking is a common problem in gunite swimming pools. Cracks occur when water seeps into the ground behind the gunite mixture from the ground above and is allowed to seep in over time. With changes in the temperature the structure expands and contracts thus overtime causing cracks. Ground shifting from changes in the water table, earth quakes and erosion from floods, freeze/thaws.
In order to prevent water seepage from the cracks in the pools marcite it is important that the gunite pool be repaired. This can be done using several repairing methods depending on the exact issue. If the plaster is in poor condition the pool plaster will need to be replaced. If the leak is small however it can often be repaired using a waterproof sealant. It is important that the proper technique is used when applying the sealant.
Cracks in the plaster can also be filled using pressurize polymer that adheres to the structure becoming a flexible hinge. This is then touched up by applying a coating of plaster in the desired thickness. A large crack in the plaster is a bit tougher. The gunite structure will need to be stabilized, and then the above technique can be applied.
With proper care of your gunite pool the pools plaster surface can stay in good shape and be maintenance free for years. Proper care includes the correct ph balance for the water, proper cleaning and upkeep on the pools internal systems. To keep the pools water in balnce it is best to check the water every few days or when water is added to the pool. Additional water from heavy rains can often cause an imperfect balance to occur in the pools water that will need to be quickly corrected to avoid damage to the pools surface.