Bondar A. Effective dry mixes for civil engineering floors

Українська версія

Thesis for the degree of Candidate of Sciences (CSc)

State registration number


Applicant for


  • 05.23.05 - Будівельні матеріали та вироби


Specialized Academic Board

К 05.052.04

Vinnytsia national technical university


The work is devoted to solving the problem of creating effective dry building mixtures for the elements of floors of civil buildings, by performing directional porousing of mixtures and activation of its components, using industrial wastes. The hypothesis for obtaining effective dry building mixtures for elements of floors of civil buildings by the introduction of fine mineral powders, as complex additives-modifiers and stabilizers of the properties of dry mixes. To this end, ash removal and carbonate limestone wastes can be applied with their complex activation together with other components of the mixture. In the work it is established that the introduction of mineral additives allows to increase the technical characteristics of foam. Thus, the multiplicity of foam without mineral additive is 15, and the resistance is 210 s. When adding finegrained carbonate limestone powder, the foam stability increases to 468 s and the multiplicity drops to 13,5. This is because the fine particles of the fillers saturate the foam solution, forming a foam system and increasing the native density. Foam resistance increases due to the increase in surface tension of the water membranes of the foaming agent around the air bubbles, due to the dissociation of mineral matter on their surface. The results of the study on the effect of the introduction of finely ground mineral powders on the compressive strength and average density of porous solutions are presented in the paper. Studies have shown that porous solutions with a mineral powder content of 10-18 %, with a cement consumption of 45 % retain a water-hardening ratio within W/S = 0,26-0,37, are characterized by the mobility of the solution mixture 6-14 cm and water-holding capacity of 95-98 % and the following parameters of the solidified solution at the age of 28 days: average density ρm = 560-1380 kg/m3, porosity – P = 23-66 %, closed – Pс. = 12-41 %, compressive strength Rst. = 2, 85 – 8,87 MPa, the coefficient of softening ks. = 0,81-0,91. After a series of researches, processing and statistical analysis of the experimental data, regression equations are obtained, which allow optimization of the parameters of the technological process of manufacturing porous dry mixes. It is determined that the average density for the designed effective dry mixes depends on the concentration of the foaming additive, water-solid ratio (W/S) and the ratio of the cost of aggregate (fillers) to the cost of cement (C/F). It is determined that the C/F ratio plays a significant role in the growth of strength: strengthen 6-10 MPa can be obtained when C/F = 0,4-1. Further experimental studies address the formulation of porous dry mixes sound insulation formulations using local mineral additives and production wastes as the active ingredient mixture along with the binder and functional additives. It is shown that when used in the technology of porous SBS is not elimination of crushing of carbonate rocks, but fine particulate limestone filler, it is possible to increase the efficiency and operational properties of porous solutions based on SBS. Activation by joint mechanical grinding and mixing in runners for 5-10 minutes of limestone waste with binder and other components of the mixture allows to obtain a decrease in the average density of the solidified solution by Δρm = 19-61 % without increasing W/C and W/S, increase in compressive strength by ΔR28 = 6-29 %, reduce cement consumption by ΔC = 20-37 %. Regulation of the rheological properties of porous solutions was due to the introduction of polymer additives. The flexural strength and shrinkage were increased by the introduction of 2-6 mm polypropylene fiber. Joint mechanical activation by the dry method of mineral fillers, binders and polymer additives has been found to improve the rheological and technological properties of porous mortar mixtures and to increase the strength of porous mortars made on the basis of developed dry mixes. The result is the production of compounds with a low average density up to 800 kg/m3 with high rheological activity (mobility – more than 8 cm, flowability – up to 21 cm, shelf life – 45 min and more), strength up to 15 MPa, improved thermal and sound insulation characteristics , reduced water demand, savings in cement and chemical additives. The order of mechanical activation of dry mixes by joint dry grinding (I stage) and subsequent additional thorough mixing (II stage) of mineral and organic components of the mixture was established. It is experimentally established that the sound insulation capacity of an obstacle, 3 cm thick, made from the developed dry mixes , is ΔL = 15-35 dB. Below are the recommendations for the manufacture and formulation of porous mixtures for floor elements, technological schemes for mechanical activation and manufacture of dry mixes economic effect of the application of the results of work is given.


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