The invention relates to a construction material mixer, in particular an asphalt or concrete mixer, consisting of a container (1) having at least one driven shaft (5) to which mixing arms (6) carrying blades (12) are fastened at intervals, the blades (12) being at a distance from the inner wall of the container (1), the mixing arms (6) being divided into an inner part (11), which is connected to the shaft (5), and an outer part (13), which carries the blades (12), and both parts being connectable to each other by means of an adjustable connection device (22). The invention is based on the fact that the connection device (22) is a snap connection device. A particular embodiment and a rapid blade replacement method are described.