Simplify the following text for a Grade 8 native English-speaking person.
Original: Corrosion and freeze\/thaw cycles may damage poorly designed or constructed reinforced concrete . When rebar corrodes , the oxidation products ( rust ) expand and tends to flake , cracking the concrete and unbonding the rebar from the concrete .
Simplified: Reinforced concrete is concrete with long pieces of metal called rebar inside to make it stronger .