These additives come in two types:

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Well-slaked lime can retain about 200% of water in the mortar. Therefore, lime mortar is much more workable than cement mortar.
In most cases, low strength is required from mortars - from 2 to 100 kg / cm2, and most often 10-25 kg / cm2. To obtain a mortar of such strength, a relatively small amount of cement is sufficient. For example, a mortar with a compressive strength of 25 kg / cm2 can be obtained by adding only about 100 kg of cement grade Rc = 400 (Rc.pl about 200) per 1 m3 of sand. However, with such a small amount of cement, the mortar will be difficult to place and easily stratifies. To obtain a workable mortar, it is necessary to spend about four times more cement, which is economically unacceptable. Therefore, in addition to cement, special additives are usually added to mortars, which give the mixtures proper workability and allow you to save cement.

Supplements

a) inorganic dispersed (finely ground), i.e. consisting of very namibia mobile database particles that are capable of retaining water well and producing a plastic dough with it (for example, clays, lime, ash, ground slags, diatomites, ground limestones, etc.);
b) surface-active plasticizing and air-entraining additives that make it possible to obtain a workable solution with significantly less water than in solutions without additives.
The wide use of additives allows saving cement, lime and other binders. This is of great importance, since mortars for masonry and plastering are one of the most common materials. Their production consumes 20-25% of all produced cements and most of the lime and gypsum supplied for construction.

Dispersed additives that impart the necessary workability (plasticity) to solutions are often called plasticizers, and solutions with such additives are called mixed (mixed cement-lime mortars, cement-clay, gypsum-lime mortars, etc.).
Mixed cement-lime mortars were first studied by the famous Russian scientist, Professor A. R. Shulyachshko, at the end of the 19th century and are widely used today.
However, the use of lime as a plasticizer in these solutions makes them not entirely economical, especially since a relatively large amount of lime has to be added to obtain a solution that is easy to place. Detailed studies of the properties of mixed mortars with various additives, conducted in 1935-1939 (by Professor N. A. Popov, Professor P. S. Filosofov, and others), showed the full possibility of replacing lime with cheaper plasticizers (in particular, clay and ash). Therefore, at present, in addition to cement-lime mortars, other mixed mortars (cement-clay, cement-ash, etc.) are also used.