Investigation of the strengthdensity relationship of light plaster on "SPADAR" foam granules

Introduction. It is a well-known fact that the higher the density of lightweight concrete (mortar) in the solidified state, the higher its strength. Thus, according to [1], at an average concrete density of 700–1100 kg/m³ (D700–1100), the strength of light concrete varies in the range of classes B3.5–B7.5, and at a density of 1200–1400 kg/m³ (D1200–1400), the strength corresponds to classes B3.5 to B25. Light mineral plasters in general can be attributed to light fine-grained concretes and, therefore, they must obey the same strength-density relationships, component consumption as light concretes (the higher the density, the greater the strength of the plaster solution). In this work, a study was conducted of light plaster based on white Portland cement and a mineral filler – foam ceramic granules “SPADAR”, for the effect on the strength of the plaster solution of its density and consumption of the main components (cement, foam ceramic filler “SPADAR”, water).

Aim. To study the dependence of the axial compressive strength of light mineral plaster based on white Portland cement and foam-ceramic granules “SPADAR” on its density and consumption of components (cement, foamceramic filler “SPADAR”, water). The range of densities for determining the strength parameters of plaster was selected by the following brands: D400, D500, D600, D700, D800.

Materials and methods. For the research, samples were used 7 x 7 x 7 cm cubes made of a light plaster mixture “SPADAR” with dry densities of 400, 500, 600, 700, 800 kg/m³ and hardened under normal conditions for 28 days. The density of dry plaster was determined by State Standard 5802–2024 “Construction solutions. Test methods”. The compressive strength of the plaster mortar was determined according to State Standard 5802–2024 [3] on 7 x 7 x 7 cm cube samples. The dependence of the strength of the solution on the consumption of its components was determined by the mathematical and statistical method.

Results. During the work, the dependence of the axial compressive strength on the density of the plaster mortar was experimentally established. As the density of the solution increases, so does its strength. The dependence of the strength of the solution on the consumption of cement and water and the density of the solution is calculated using a mathematical and statistical method. Thus, it was found that with an increase in cement consumption from 185 to 435 kg per 1 m³ of mortar mixture, the strength of the solution increases from 1.5 to 8.5 MPa. At the same time, the density of the solution increases from 400 to 800 kg/m³. This is true for the consumption of foam granules in the range of 0.7–0.85 m³/m³ of solution.

Conclusions. Based on experimental data and mathematical and statistical calculations, it was found that with an increase in the density of the plaster mixture from 400 to 800 kg/m³, the strength of the studied solution for axial compression increases exponentially from 1.5 MPa to 8.5 MPa, while the consumption of binder and water increases. The consumption of SPADAR foam granules in the range of 0.7–0.85 m³/m³ of solution does not significantly affect the change in the strength parameters of the tested compounds. This study has found further practical application in the development of the composition of light plaster “SPADAR SK 750” with increased density and durability.

1. Recommendations on the selection of lightweight concrete compositions (to State Standard 27006–86). Gosstroy of the USSR. Moscow: TsITP Gosstroya SSSR. 1986. 96 p.

2. State Standard 33083–2014. Dry building plaster cement binder mixes. Specifications. Moscow: Standartinform Publ., 2019. (In Russian).

3. State Standard 5802–2024. Mortars. Test methods. Moscow: Standartinform Publ., 2025. (In Russian).

4. Zedginidze, I.G. Experimental planning for the study of multicomponent systems, Moscow: Nauka Publ., 1976, 390 p.

5. Bondar A.G., Statyukha G.A. Planning an experiment in chemical technology. Kiev: Vysshaya shkola , 1976. 181 p.

6. SP 82–101–98. Manufacturing and usage of solutions in construction industry. Moscow: Gosstroy of Russia, 1999. (In Russian).

7. Bazhenov Yu.M. Technology of concrete. Moscow: ASV Publ., 2002. 500 p. (In Russian).

8. Bazhenov Yu.M., Korovyakov V.F., Denisov G.A. Technology of dry building mixes. Moscow: ASV Publ., 2011. 112 p. (In Russian).

9. Korneev V.I., Zozulya P.V., Medvedeva I.N., Bogoyavlenskaya G.A., Nuzhdina N.I. Compounding guide to dry building mixes. St. Petersburg: RIA “Quintet”, 2010. 318 p. (In Russian).

10. Korneev V.I., Zozulya P.V. Dry building mixes. Composition, properties: Textbook. Moscow: RIF «Stroymaterialy», 2010. 320 p. (In Russian).