The volumetric content of cement is calculated based on the requirements of durability and operating conditions. The durability of the first three degrees for structures with air humidity in rooms of 60% and foundations located above the level of groundwater will require the addition of 75 kg of cement to each cubic meter of cement-cement mortar. In the case of mixtures with clay, it is necessary to increase the consumption by a third, which is guaranteed to be suitable for buildings of I and II of the durability group. With stronger operational values of moisture, the share of cement increases by another third, and should not be less than 125 kg per cubic meter of the mixture with sand of natural humidity (1-3%). In the case of completely dry sand, the consumption of connecting cement should be increased by another 5%, and vice versa, with increased humidity, the sand lies more tightly, which must be taken into account by reducing the flow rate of cement by 10%.
For the preparation of solutions, you should use sand with particles of at least 2 mm, if possible clean and carefully sifted. In the case of a bottle masonry, dispersion of the component of the sand can be increased to 5 mm. The addition of organic and inorganic plasticizers allows us to achieve greater ability to water maintenance and greater mobility. To obtain a high degree of durability of the building, the proportion of the plasticizer, clay, for example, should not exceed cement by mass fraction, exceeding 50% is allowed only for the III class of durability. The maximum concentrations of the plasticizer are customary to be determined by immersion in the finished solution of a special cone. Depending on the depth of subsidence, a conclusion is made on the suitability of the solution for use. Plasticizers for masonry, which are in high humidity conditions, is not recommended. In these cases, classic cement-sand solutions with strength brands of at least 25 are used.