A scabbler machine for breaking concrete etc. having a number of scabbling bits made up of a shank for connection to the reciprocal piston of the scabbler machine and a head provided with tungsten carbide, or like, cutting members. To ensure complete scabbling of the surface to be treated the head of the scabbling bits have portions which overlie portions of other bits so that the bits overlap one another in the direction of movement of the scabbler machine over the surface to be treated.