The article deals with the influence of complex mineral additive "chemical water treatment sludge + flask or fly ash" on the frost resistance of building mortars depending on the redispersible polymer powder dosage from 0 to 3%. According to the results of research after 100 freeze-thaw cycles, the condition RF/R0 > 1.2 is met, and the k value according to clause 5.2.4 of GOST 10060-2012 after 100–125 freeze-thaw cycles ranged from 0.94 to 1.73, the minimum value of the relative modulus of elasticity EF/E0 = 0.97, and the residual expansion deformation did not exceed 0.03%. Building mortars with fly ash have higher frost resistance according to the bending strength criterion in comparison with mortars with flask. The frost resistance criterion for bending strength is more “strict” than the criteria according to GOST 10060-2012. It is not advisable to use a dosage of RPP greater than 2% for the production of building solutions with increased frost resistance requirements.

Keywords: frost resistance of building mortars, frost resistance criteria, redispersible polymer powders, compressive and flexural strength, elastic modulus, permanent expansion deformation

The article deals with the results of research on the influence of the dosage and composition of the complex mineral additive containing chemical water treatment sludge with gaize, burnt rock or fly ash. The result of investigation is the equation for the change in shrinkage deformations over the time for mortars containing a complex mineral additive in comparison with a standard mixture without additives. There is evaluating of the influence of changes in the mortar moisture on the amount of shrinkage deformation. On the base of the research, we astablished the dependences of shrinkage deformations on the moisture content of the mortar, according to the composition and dosage of the complex mineral additive. The study revaels the influence of a complex mineral additive on shrinkage deformations. The equation has been obtained that describes the change in shrinkage deformations depending on the relative humidity and it has been shown that the tested mortars with a rational composition and dosage of a complex mineral additive with an average air humidity of the driest month in Rostov-on-Don of 47% will not exceed 0.55 mm/m . Shrinkage deformation with the ratio of the complex additive with fly ash or burnt rock 20-30% are 0.42-0.79 relative to the additive-free standard.

Keywords: dry construction mixture, shrinkage, mineral additive, mortar, chemical water treatment sludge, burnt rock, fly ash