How should I reconnect my light fixture with red, white, and blue wires?
The blue wire, coupled with the very notable total lack of any black wire, indicates your house is NOT wired in cable.  It uses individual wires, which means it is in the conduit wiring system.  Given your ceiling being solid concrete, that is no surprise.   As such, wire colors may be whimsical as compared to diagrams you see on the Internet.  In conduit: 


neutral will be white or gray, 
ground will be green, yellow/green stripe, bare or the conduit itself
hot will be all other colors.  Hot will never use white wire because that is not allowed in conduit. 


Generally speaking, when you see 


a clump of hots -- note that a clump of hots might include one white wire
a clump of all white wires, and 
a solitary hot 


That connects like this.  The clump of hots is always-hot and you will not be using it.   The clump of all whites is kept together, and the neutral from the lamp is added to it.   The solitary is switched-hot for the lamp.