Technically, mortar is defined as a mixture of aggregates with a grain size of in general less than 4 mm (sometimes less than 8 mm, e. g. mortar for special decorative renders or floor screed mortar), one or more binders and possibly additives and/or admixtures. Factory made mortars are marketed in two principal forms: drymix mortars and ready mixed mortars. While dry mixed mortars need to be mixed with water and sometimes other compotents on site before being applied, ready mixed mortars, incl. mortars with inorganic binders, already contain the water and in most cases are ready to use products.

The most important functions of mortar are:

• connecting construction products and levelling tolerances (e. g. masonry mortar and tile adhesive mortar)
• providing level or smooth finishes (e. g. floor screed mortar, internal plastering)
• protecting against weathering (e. g. external rendering)
• improving thermal the thermal performance (e. g. external thermal insulation composite systems, thermal insulation rendering mortar, lightweight masonry mortar)
• improving acoustic insulation (e.g. floor screeds)
• repairing and renovating constructions (e. g. concrete repair mortar, damproofing mortar, or renovation mortar