Mortar and concrete both are made from Portland cement with added ingredients. Mortar is made of Portland cement, sand and water. It is the "glue" that binds bricks and blocks together to build structures. Concrete is made of Portland cement, sand, water and a stony aggregate such as gravel. It pours into molds or forms to make structures such as walks, walls and foundations. The two construction materials call for different types of powered mixers.
A mortar mixer essentially is a stationary horizontal trough inside of which is a motor-driven horizontal shaft with attached paddles that perform the mixing operation. The mixing paddles can be powered by an electric motor or gasoline engine. Some mortar mixers use a circular vertical drum. In these machines, the mixing shaft and its attached paddles are oriented vertically.
Scrape and Churn
The dry ingredients that will make up the mortar are poured into the mixer and water is added. The motor-driven paddles scrape and churn the ingredients into mortar. To empty horizontal mortar mixers, the open-topped trough tips sideways until the mortar pours out over the side. In small vertical-drum mixers, the entire drum can tip to pour out the mortar. In larger models, the mortar pours out through a side door just above the base of the drum.
A concrete mixer features a round rotating barrel-like drum with paddles fastened to the inside of the drum. In operation, the drum tips up at an angle and a gasoline engine or electric motor rotates the drum. One end of the drum is open for loading the concrete ingredients and unloading the finished concrete.
Lift and Drop
As the concrete mixer's drum rotates, the paddles lift and drop the ingredients over and over again to mix up a slurry that will later harden into concrete. When the mixing is done, the drum tips down to pour out the wet mixture for use. A concrete mixer can also make mortar but a mortar mixer cannot make concrete because the gravel in the mixture will jam the moving paddles.