Mud mixers and concrete vibrators produce a thorough, cavity-free concrete mix that sets properly, forms a strong bond with rebar, and remains structurally sound. Mud mixers rotate mixing paddles to stir concrete, grout, mortar, and other thick liquids to a uniform consistency. Their high-torque motor drives the paddle through viscous materials that could burn out a drill being used as a mixer. Concrete vibrators remove air pockets from newly poured concrete to ensure that it consolidates and reaches its maximum finished strength. They prevent honeycombing (bug holes) and properly pack the aggregate to increase density and reduce reworks and surface patching.