Will zombies be super strong?

Unless the agent causing the zombification also causes significant changes to the person's body, then no a zombie will not have super strength. The idea of super-zombies comes to pop culture mostly from the Resident Evil franchise and it should be noted that those creatures are the product of a mega-corporation's evil experimentation. Assuming that the zombification is caused by something along the lines of a prion, virus or parasite then the zombie wouldn't have any more strength than the infected human had in the first place. It is generally theorized that the pain receptors in a zombie brain will be inoperative. Because of this the zombie might appear to have strength surpassing a human, but it simply won't be the case that you'll see a zombie tearing a door from its hinges or overturning a car.