INVESTIGATION OF THE INFLUENCE OF ORGANOMINERAL ADDITIVES ON THE COLLOID-CHEMICAL PROPERTIES OF GEOCEMENT DISPERSION

The object of research is the geocement dispersion of the heulandite-clinoptilolite composition of the structural formula Na 2 O × Al 2 O 3 × 6SiO 2 × 20H 2 O, modified with an organomineral additive The results of the effect of an organomineral additive on the colloidal-chemical properties of geocement dispersion are presented. Mathematical models that characterize the effect of the concentrations of constituent organomineral additives on changes in its basic physical and colloidal chemical properties are obtained: – conventional viscosity; – density; – wetting angle; – surface tension; – works of adhesion, cohesion and wetting of geocement dispersions, factors X1 ... X3 have an influence that are significant. Also, the joint effect of factors, respectively, x1x2x3, x1x2, x1x2 and x1x3 has a significant effect. The coefficients of wetting and spreading of geocement dispersions are significantly influenced only by the joint action of the factors x1x2x3. Relationship is established between the conditional viscosity and the wetting coefficient, between the wetting angle, adhesion, wetting and spreading work and between the density, surface tension and work of cohesion. The composition of the organomineral additive is optimized and the areas of permissible concentrations of its constituents are determined: – along the X1 axis, 2–2.3 % of polymer RI-551Z; – along the X2 axis, 2.1–2.5 % of microcalcite; – along the X3 axis, 4.5–6.5 % of aluminate cement, which, when introduced into a geocement dispersion, allows Na 2 O × Al 2 O 3 × 6SiO 2 × 20H 2 O to stabilize its colloidal-chemical properties. It is determined that the changes in the values of the other output parameters are tied to the change: – the conditional viscosity and their values are in the following limits: r =1.571–1.766 g/cm 3 , cos Q =0.50–0.67; – surface tension s =114–128 mN/m; – works of adhesion, wetting and cohesion, respectively, 184–204 mN/m; – coefficients of wetting and spreading -0.77–(-)0.84, -37–(-)55 mN/m.


The object of research and its technological audit
The object of research is the geocement dispersion of the heulandite-clinoptilolite composition of the structural formula Na 2 O×Al 2 O 3 ×6SiO 2 ×20H 2 O, modified with an organomineral additive. This additive consists of: -redispersible in water dispersion powder of the terpolymer of ethylene, vinyl laurate and vinyl chlo-ride -Vinnapas RI-551Z (Vinnapas 8031 H, Wacker Polymer Systems, Germany); -microcalcite fraction of 2 microns (Nigtas, Turkey); -aluminate cement Istra 40 (HeidelbergCement, Germany), taken in certain quantitative relationships. Positive from the use of organomineral additives, in addition to elasticity, hydrophobicity and strength, is the improvement of the colloidal-chemical properties of geocement dispersion, namely: -wetting contact angle; -surface tension; -works of adhesion, cohesion and wetting; -coefficients of wetting and spreading. For investigations in this work, a geocement dispersion of the composition Na 2 O×Al 2 O 3 ×6SiO 2 ×20H 2 O, obtained on the basis of metakaolin, microsilica, and sodium soluble glass is used. Optimization of the composition of the organomineral additive that affects the colloidalchemical properties of the geocement dispersion is carried out using a three-factor simplex-center method of experiment planning in the mathematical environment of Statistica 12.0.
The number of additives is chosen as the variable factors, %: RI-551Z (factor X1), CaCO 3 (factor X2) and AC (factor X3), the changes of which are given in Table 1. As the output parameters are chosen: conditional viscosity, density, wetting angle, surface tension, work of adhesion, cohesion and wetting, wetting and spreading coefficients. TECHNOLOGY AUDIT AND PRODUCTION RESERVES -№ 3/1(35), 2017

ISSN 2226-3780
The results of the experiment planning are given in Table 2.  The rheokinetic properties of the constituent organomineral additives have been separately studied. But there is no data on the complex or joint organomineral additive on the colloidal-chemical properties of geocement dispersion, as the basis for obtaining protective coatings, adhesives and other types of composite materials.

The aim and objectives of research
The aim of research is investigation of the colloidalchemical properties of a geocement dispersion modified with a complex organomineral additive.
To achieve this aim it is necessary to accomplish the following tasks: 1. To optimize the composition of the complex organomineral additive.
2. To determine the physical and colloidal-chemical properties of geocement dispersion.

Research of existing solutions of the problem
Among the main ways to eliminate the gap in the study of the colloidal-chemical properties of geocement variances revealed in the resources of the world scientific periodicals, the following can be singled out: -the quality of the binder, which is characterized by viscosity, surface tension, the presence of gels and microgels, particle size, colloidal stability and adhesion strength.
The consistency of the binder itself and the strength, hardness and durability of materials based on it depend on the type and composition of these indicators [1][2][3][4][5][6][7][8][9][10][11][12]; -dependence of the surface tension of uncured mineral binders on the nature of the solvent. With an increase in the concentration of solvents, the surface tension of unconfined binders decreases, and the greater, the less the surface tension of the solvents [25][26][27].
In particular, works [28][29][30][31] are devoted to the study of adhesion phenomena, wettability and spreading at the interface of condensed phases. The work of Wa adhesion was calculated on the basis of the experimental values of the surface tension at the liquid-gas interface (σ) and the wetting contact angle (θ) by the Dupre-Young equation: The work of cohesion was determined from the cost of energy for a reversible isothermal discontinuity of the binder in a section equal to a unit area. Since, a surface forms during the rapture in two units of area, the work of cohesion is equal to twice the value of the surface tension at the boundary with the gas: The work of wetting was calculated by the formula: The coefficients of wetting and spreading were determined from the ratio of adhesion to cohesion and their difference: f=Wa-Wc = σ´(cosθ-1).
The authors of [27] showed that the deepening of knowledge on the colloidal properties of binders greatly simplifies the flow of technological processes for the manufacture of materials, as well as an understanding of the degree of their filling.
An alternative solution to the problem, presented in [7,16,17,29], does not give a clear picture on the determination of the colloid characteristics of binders in a wide range of concentrations of additives that affect these properties.
In the opinion of the authors of the works [1,7,18,[25][26][27], it is possible to obtain more correct colloidal characteristics of binders only with the use of modern instruments [32].
The ways to improve the approaches to calculating the colloidal properties of suspensions were considered in [25,29].
Thus, the results of the analysis allow to conclude that an understanding of the nature of the manifestation of the colloidal-chemical characteristics of suspensions leads to the production of high-quality and durable composite materials, increases the degree of their filling and, as a consequence, the field of application.

Methods of research
Traditional methods of colloid chemistry were used to determine the surface tension and the contact angle of wetting [25,26,[29][30][31] -the stalagmometric method (the droplet counting method) and the sessile drop method. It is assumed that at the moment of separation, the surface tension force is equal to: where R -the radius of the hole from which the drops flow; Σ -the surface tension of the liquid. At the same time, the surface tension force is equal to the force of gravity: where m -the mass of one drop. So, It is practically impossible to measure the exact radius of the capillary hole, so a comparative method was used with the known surface tension of a standard liquid, for example, water: where σ 0 , σ 1 -the surface tension of water and the liquid, respectively, m 1 и m 0 -the mass of one drop of water and the liquid, respectively. The cosine of the contact wetting angle was calculated by the formula: The error of the methods is 10 %. Plate of black metal protruded from the rust deposit was the substrate.

Research results
As a result of optimization, mathematical models that characterize the influence of the concentrations of the constituent organomineral additives on the changes are obtained: relative viscosity, h, s(ВЗ-5): v = 185x1+93х2+101х3-56x1х2-80x1х3--36х2х3+345x1х2х3+0; -density of geocement dispersion, , g/cm 3 : Analysis of mathematical models shows that the changes in the values of the output parameters displayed in Table. 3, namely: conventional viscosity; density; wetting angle; surface tension; works of adhesion, cohesion and wetting of geocement dispersions, factors X1...X3 have an influence that are significant. Also, the joint effect of factors, respectively, x1x2x3, x1x2, x1x2 and x1x3 has a significant effect. .60 Note: h -conventional viscosity;  -the average density; cosq -the cosine of the contact wetting angle;  -surface tension; Wawork of adhesion; Wc -work of cohesion; Ww -work of wetting; s -wetting coefficient; f -spreading factor; K -control composition.

ISSN 2226-3780
The coefficients of wetting and spreading of geocement dispersions are significantly influenced only by the joint action of the factors x1x2x3.
Graphical interpretation of the models is shown in Fig. 1.
When analyzing the ternary surfaces of the influence of the concentrations of the constituents of the complex organomineral additive on the properties of the output parameters (Fig. 1, 2), the relationship between the conditional viscosity and the wetting coefficient is traced. And also between the wetting angle, the work of adhesion, wetting and the spreading coefficient and between density, surface tension and work of cohesion. The defining index for assessing the colloidal-chemical properties of non-cured geocement dispersion is the conditional viscosity index, which should not exceed a value greater than 100 s.
The change in the conditional viscosity ( Fig. 1, a) is more affected by the concentration of the polymer RI-551Z, the optimum amount of which is in the range from 2 to 2.31 %. Naturally, changes in the values of other output parameters will be tied to the change: -the conditional viscosity and their values are in the following limits: =1.571-1.766 g/cm 3 , cos=0.50-0.67; surface tension =114-128 mN/m; works of adhesion, wetting and cohesion, respectively, 184-204 mN/m; -coefficients of wetting and spreading -0.77-(-)0.84, -37-(-) 55 mN/m (Fig. 1, b, c and Fig. 2, a-f).

SWOT analysis of research results
Strengths. The introduction of a complex organomineral additive containing from 2 to 2.3 % of polymer RI-551Z, microcalcite from 2.1 to 2.5 % and aluminate cement from 4.5 to 6.5 % contributes to the stabilization of the conventional viscosity, a decrease in surface tension, increase the work of adhesion and increase the wetting coefficient. It is also possible to regulate both the colloidal-chemical and technological properties of the geocement dispersion, as well as the degree of its filling with functional fillers. This will give a real opportunity in obtaining an even greater range of geocement-based materials.

ISSN 2226-3780
Weaknesses. The negative effect of the object of research on its internal factors manifests itself in a constant rate of flow of the chemical reaction between the components of the dispersion and the mineral constituents of the organomineral additive. This leads to a change in the colloidal-chemical properties in time, namely, to thickening and hardening of the composition.
Opportunities. Opportunities for further research will be directed to the search for stabilizers and retarders of the rate flow of chemical reaction between the components of the geocement dispersion and the mineral constituents of the organomineral additive.
Threats. The time factor and external factors may have a negative effect on the research object: temperature drop, mechanical shake, which will be the subject of further research.

Conclusions
1. Optimization of the composition of the organomineral additive is carried out and the area of existence of the optimal concentrations of the constituent organomineral additives is determined, namely: -along the X1 axis, 2-2.3 % of polymer RI-551Z; -along the X2 axis, 2.1-2.5 % of microcalcite; -along the X3 axis, 4.5-6.5 % of aluminate cement, which, when introduced into a geocement dispersion, allows Na 2 O×Al 2 O 3 ×6SiO 2 ×20H 2 O to stabilize its colloidalchemical properties. The introduction of geocement dispersion into the composition of an organomineral additive of optimal concentrations will allow in time to stabilize the values of its viscosity (not higher than 100 s), to reduce the wetting angle, to reduce the surface tension, to increase adhesion and to reduce the wetting coefficient.
2. As a result of the experiment, a relationship is established between the conditional viscosity and the wetting coefficient, between the wetting angle, adhesion, wetting and spreading work and between the density, surface tension and work of cohesion. It is determined that the changes in the values of the other output parameters are tied to the change: -the conditional viscosity and their values are in the following limits: =1.571-1.766 g/cm 3 , cos=0.50-0.67; -surface tension =114-128 mN/m; -works of adhesion, wetting and cohesion, respectively, 184-204 mN/m; -coefficients of wetting and spreading -0.77-(-)0.84, -37-(-) 55 mN/m ( Fig. 1, b, c and Fig. 2, a-f).