Have a 22 by 45, deep end 10 ft, walls 4 ft high, rebar 1 ft centers, built in 1979, all concrete. Always drained every year and over time, because of freezing and thaws, concrete flaking on one section of shallow area floor.  Do a search on a concrete product used to rebuild highway expansion joints and patch areas called   " SET 45 " The repair area has been under water for 10 years and is like the day it was repaired, perfect bond. We pump the pool down to about 6 inches of water in the fall. The freezing of the concrete causes the most damage, no wall  damage. The Set 45 is a powder mixture, mix with water, and a thermal  reaction starts the cure process. Mixed it to a consistency  of a very wet concrete mortar mix to the point where it would self spread and poured it on the floor and  2 by 4 level it. Pool preparation, high pressure 2 to 3000 psi , blow out every thing loose and then some, let dry, wet area with hose spray, mix Set and pour, cure time is quick. Don't let mixed product sit in bucket, will set. You can put layer over layer while the first layers starting its set. The walls, V out the cracks, pressure wash, dampen work area start at bottom and  work up. Just like point tucking brick with a wet mortar mix . Read the specs and application uses on the SET 45 on the internet. Does not expand or contract with temperature changes.   Am aware that you have to drain the pool every year because of community liability problems, the temperature cause problems. No expansion joints on 45 ft walls and have a hairline crack at the 22 ft point on each wall, No water loss. If you have questions, my e-mail should be in NAT site info. 

Bob Chillicothe Ohio