SCIENTIFIC PRINCIPLES AND THE GENERAL METHOD OF DESIGNING THE...

SCIENTIFIC PRINCIPLES AND THE GENERAL METHOD OF DESIGNING COMPOSITION OF THE OPTIMAL STRUCTURE SUIT

The optimization of the structure and scientifically substantiated determination of the material composition of various artificial conglomerates is carried out by a common (unified) design method. There may be methods and specific ones developed for each species of conglomerate. Some specific features are also highlighted when applying a common (single) method. However, the scientific principles underlying the design of the composition by any method remain unchanged. The main scientific principles include: the greatest approximation of technological regimes and parameters used in laboratory design practice, to the actual production technology of a conglomerate mixture and products; ensuring the greatest possible uniformity in the distribution of particles of different fineness, pores, interfaces and other structural elements in the volume of the material; providing specified properties at the level of numerical values ​​of extrema with the optimal structure; application of general objective laws inherent in conglomerate materials of the optimal structure and, including, the law of congruence, the law of alignment, the law of strength and others; use of the general method and means of designing the optimal composition and accurate implementation of the design composition in the production.

The practical purpose of the design is to determine the consumption of the original components (by weight) per ton or one cubic meter of a dense mixture. After molding, consolidation and solidification, the mixture acquires the optimal structure of an ICS, which is shaped into the product or structure used in the installation of buildings and structures in construction.

The implementation of the general design method for the optimal composition of ICS is an essential part of the technological process, which in turn is the guarantor of the highest quality of the manufactured products in accordance with the received design composition. This method involves three steps.

The first stage provides for a number of initial operations: substantiation of the main indicators of the construction and operation properties of the conglomerate, based on a careful analysis of the actual conditions of its operation in structures; choice of source materials, corresponding to their functional purpose as components of the conglomerate; the definition or verification, if specified, of the technical properties of the accepted materials with the use of standard specifications and taking into account production or projected technological parameters and regimes. For responsible construction projects, the results of the first stage of designing the conglomerate's composition can be considered together with the construction organization (customer) as a specific technical task.

The second stage is a calculation and experimental one and is designed to determine the consumption of accepted components per ton, or 1 m, or for another quantity of the mixture (for example, for one mixture in the mixing apparatus volume). It is executed in a certain sequence of operations, based on the basic dependencies in their mathematical expressions, which can be used in programs that are later implemented with the help of machine technology. The first operation in this sequence is the determination of the calculated activity of the binder and the minimum phase ratio, i.e., R * and c7f. However, the definition of the calculated activity is more often attributed to the first stage of the design of the composition with the technical evaluation of the raw materials. Instead of strength, another property of the material-elastic deformation, density, viscosity, frost resistance, etc., can be adopted, depending on the purpose of the ICS. The second operation at this design stage is the determination of the composition of the dense fill aggregate p n (Figure 3.14). The third and most capacious operation is the identification of the number of initial components in the mixture from which the conglomerate is formed. It is performed with the help of formulas and calculated characteristics, in a machine-free fashion or with the use of electronic computers. If necessary, determine the indices of the same properties for other values ​​of T and v.

The third stage is the preparation of trial mix of the design composition, if possible in production conditions, for example, in the mixing plant of the plant. With the help of laboratory tests, the quality of the mixture and the molded conglomerate is established for all the properties provided. Particularly establish the presence of an optimal structure, for example, by the similarity indicator or by the curves of the optimal structures.

Fig. 3.14. Dependence of the bulk density of the aggregate mixture (p and ) on the content of the line (P)

If deviations are noted, then the composition is corrected. The latter may be required when mass production is produced at the plant, if the raw materials receive from time to time a different composition and other properties than were accepted in the laboratory at the design stage of the composition.

The rational sequence of designing the ICS composition in general form is described below, with concrete examples in some subsequent chapters for machineless and machine methods.

The first stage: determination of the calculated activity of the binder (A *) as the matrix part of the ICS and the minimum value of c7f, which ensures the optimum structure with the adopted technological parameters. To do this, from a mixture of binder with 3-4 different c/f, which usually differ by a value of 0.02-0.05, samples are made that are established by standards in assessing the properties of the material under test. For the first estimated experiments, samples can be taken smaller in size in order to economize the initial components. After all the tests and the graphical construction, the functions A = A/() are found and, if necessary, the desired value c */p is clarified for the greatest strength of the binding substance A *.

In the first stage, also the composition of a dense mixture of aggregate (large - A and fine - M) is determined by calculation or, more often, experimentally, by determining the mass ratio of the quantity MIK.

The second stage begins with the specification of specific mathematical dependencies, which will be used in calculations on the composition of the conglomerate mixture. Here you will also need to perform two operations, one of which is auxiliary (experimental), the other - the main (calculated).

Auxiliary operation is necessary to determine the exponents n and m, used in the strength formulas and compositions. For this purpose, according to the laboratory data, a curve of optimal structures is constructed (Fig. 3.15) for an arbitrarily chosen value (c/φ) π at the point A on this curve. Find the value of Ra on the curve TIE, and also the value (c + φ) at the point B. The strength of Ad is also present on the curve KL, which at the beginning of the experiment, although not yet, but about its probable existence as a curve of optimal structures on the plane x-y from the theory of ICS is known. And then the obtained data A, (c/ff) in, (c/f) is sufficient to determine the values ​​of the exponents of the power nm, according to formulas (3.3) and (3.4), since the other required values ​​of A * and c7f were already defined on the first

Fig. 3.15. Graphs of curves of optimal structures in a spatial coordinate system A = A//; c + φ) (a) and on the planes R = f i (c/φ); L =/ 2 (with + fі); with/F =/Z (с + Fі) (б);

c + φ = 100- (n + n) in %

design phase, namely:

here it is important to consider that n is a constant, while t is a variable that requires correction for other values ​​of c/φ or R. This completes the second stage support operation. It is necessary to move to the main operation of this stage - the calculation of the number of component costs in the project mix composition. Rational sequence of calculations:

a) the desired phase ratio of the binder, using the formula (3. 4), and

exactly:

where R? ad is the strength of the ICS, the composition of which is projected; b) the desired c + φ conglomerate, using the formulas (3.3) and (3.4),

namely:

where t x differs from the previously obtained value t , since it is determined at the new value (c/φ) /sub> cc, and not with the previous (c/f) q, namely:

c) the required amount of liquid component c per 1 ton of the mixture:

d) the required amount of dispersed solid component of the mixture per 1 t:

e) the required amount of placeholder:

e) the required amount of fine component in the filler at the previously found ratio M/K, namely:

g) the required amount of a large component in the placeholder:

All the found values ​​of с, F, М, К are multiplied by 10 because in 1 ton (1000 kg) each 1% is 10 kg.

If necessary, recalculate the mass of the components per 1 m of the conglomerate mixture (excluding air pores) in the following sequence:

(a) Determination of the absolute volumes of the initial materials (provided that the values ​​of their true densities 6c, 6f, 5m and 6k are known or found at the first design stage), necessary for the formation of 1 ton of the mixture (l):

10-s/bs; Yu-f/bf; 10 M/5 m; 10K/5k; b) determination of the average density of the conglomerate mixture (kg/m):

c) determination of materials per 1 m conglomerate mixture (kg/m): liquid medium: c-uis & quot ;; solid phase: F-у И ск; fine aggregate: M-ui & quot ;; of a large aggregate: К-у Н ск -

The third stage: preparation of control batch (better in production conditions) with an assessment of its quality characteristics. If necessary, adjust the design composition taking into account the moisture content of the mineral components of the mixture used. The projected and corrected composition is transferred to the production for use in construction.

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