The Groutmaster combines the advantages of a colloidal mixer, a buffer tank with agitator and a worm pump. This makes it possible to make homogeneous mixtures, even with problematic products such as bentonite and mixtures with additives. A large mixing funnel keeps the mixed products in suspension. The exchangeable pump bodies enable a wide range of pressure and flow rate. It is also possible to adjust the flow rate of the pump by changing the speed of the motor.