① Twin-shaft ribbon screw mixer: Due to the concrete is basically piled up near the discharge gate while the twin-shaft ribbon screw mixer completes mixing, the discharge will take a short time. The unloading gate is controlled by the electric device which can adjust the opening degree so that the unloading gater will not be stuck when closed. During the unloading process, the ribbon screw blades will rotate at a low speed, which is beneficial to remove the concrete remaining in the mixing tank as well as can effectively avoid the parabolic phenomenon during the unloading of the disc machine. ② Single-shaft ribbon screw mixer: Due to the limitation of the system structure, the opening size of the discharge gate is difficult to adjust, which will have a greater impact on the discharge of different proportions of concrete. Besides, the discharge gate is easy to be stuck during the closing process. Especially in the emergency closing state, problems are more likely to occur, and the closing of the discharge gate is not good.