Материал: Russian Journal of Building Construction and Architecture

Fig. 1 shows an approximation dependency of the compression strength of the and sandy loam phosphor-gypsum on the pressing pressure, MPa, and time of mixing, min.

Fig. 1. Approximation dependence of the strength on the pressing pressure, MPa, and time of mixing, min. The energy of the connection is represented with a dependence quadratic function on the time of mixing

of the mix and the compression of the molecules during the pressing from all sides is similar to a cubic polynom, which corresponds with the area of a maximum set of the pressing pressure strength of 21,7 МPа and the time of mixing of the mix of 82 min. In the range of 0 to 10 МPа there is a small gradient of an increase

in the strength, which is due to another packing of the mineral particles. A further increase of the pressing pressure of over 22 МPа does not increase the strength, which is due to the typical composition of the lime and sandy loam phosphor-gypsum material

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Russian Journal of Building Construction and Architecture

Fig. 2 shows a model dependency of the strength on the pressing pressure, МPа, and time of mixing, min.

Fig. 2. Model dependency of the strength on the pressing pressure, МPа, and time of mixing, min. The maximum strength of the examined material corresponds with the point of an optimal solution of the equation with the pressure of 21.75 МPа and the time of preliminary mixing of 82 min

Conclusions. The research methoв is presented which is used to obtain the analytical dependence of the strength of the lime and sandy loam phosphor-gypsum material on the technological parameters (pressing pressure and time of mixing) where the energy of the connection is presented as a quadratic function of the dependence of time on mixing of the mix and the compression of the molecules from all sides is similar to a cubic polynom, which shows the range of the maximum set of the strength under the pressing pressure of 21.7 МPа and time of mixing of the mix of 82 min.

In the range of 0 to 10 МPа there is a small gradient of an increase in the strength, which is due to another packing of the mineral particles. A further increase of the pressing pressure of over 22 МPа does not increase the strength, which is due to the typical composition of the lime and sandy loam phosphor-gypsum material

The use of this research method would allow the technological process to be optimized and the specified properties of the lime and sandy loam phosphor-gypsum material to be controlled.

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DOI 10.25987/VSTU.2018.41.1.006

UDC 691.327.32

S. D. Semenyuk1, Yu. G. Moskal'kova2

CALCULATION METHOD FOR THE FORMATION

OF MICROCRACKS TAKING INTO ACCOUNT THE DENSITY

OF CLAYDITE CONCRETE

Belarusian-Russian University

Republic of Belarus, Mogilev

1D. Sc. in Engineering, Prof. of the Dept. of Industrial and Civil Construction, tel.: +375(29)7433872, e-mail: skzs@tut.by

2PhD in Engineering, Assoc. Prof. of the Dept. of Industrial and Civil Construction, tel.: +375(29)7429183, e-mail: julia43@tut.by

Statement of the problem. An important aspect of concrete behaviour under loading is the formation and development of microcracks. The existing methods for the calculation of values of the limits of microcrack formation for lightweight aggregate concrete do not provide sufficient convergence with the experimental data. In this regard, it is advisable to derive new formulas applicable for lightweight aggregate concrete.

Results. The paper presents the test results on concrete of different strength and density classes. It also suggests new formulas for the calculation of the limits of microand macrocrack formation. According to the obtained research results, an empirical coefficient is introduced based on the density class of lightweight aggregate concrete.

Conclusions. The calculation method of the upper and lower limits of microcrack formation for lightweight aggregate concrete of various strength and density classes is proposed. The method is harmonised with the provisions of the Eurocode 2. At the same time, good convergence with the experimental data is provided.

Keywords: lightweight aggregate concrete, claydite, limits of microcrack formation, density, density class.

Introduction. The use of construction and heat insulation lightweight concrete is becoming increasingly common in construction. Apart from good heat insulation properties, this type of concrete has a sufficient fire resistance [10]. Therefore it is of a lot of importance these days to develop relevant theories for calculating and designing load-bearing structures made of light concrete.

© Semenyuk S. D., Моskalkova Yu. G., 2019

*The research was conducted as part of the state research program “Physical Material Studies, New Materials and Technologies”, subprogram 8.8 “Construction Materials”, № state register 20162027, registration date 30.05.2016, ГБ 1621Ф.

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