Effect of aggregate type on strength and deformation properties of high-strength concrete during heating

Introduction. High-strength concrete is widely used in contemporary construction. Expanded introduction of high-strength concrete necessitates the need for studying its behavior at high temperatures (in case of fire) in order to ensure the required fire resistance of load-bearing reinforced concrete structures made of high-strength concrete in terms of fire safety of buildings and structures.

Aim. To determine the effect of aggregate types on strength and deformation characteristics of high-strength B100 concrete when heated to temperatures from 100 °C to 800 °C with a step of 100 °C.

Materials and methods. Laboratory tests of prism strength and elastic modulus of basalt and granite high-strength concrete were carried out on prism samples in a heated state according to standard methods using special heating equipment combined with laboratory pressure equipment.

Results. The authors determined structure behavior factors of basalt and granite high-strength concrete during heating, specifying the decrease in compressive strength and elastic modulus. Deformation diagrams during axial compression of high-strength granite and basalt concretes under heating were drawn.

Conclusions. The dynamics of reduction in strength and deformation properties is similar for granite and basalt high-strength concrete under heating and is specific for silicate aggregate concretes. The elastic moduli of basalt high-strength concrete are higher than those of granite high-strength concrete, both at 20 °C and when heated, thereby determining the dependence of high-strength concrete deformation properties on the types of aggregates. Deformation diagrams during the axial compression of high-strength granite and basalt concretes showed specific character: unilinear – when heated to temperatures of about 300–400 °C, bilinear – at higher heating temperatures, therefore differing from traditional ideas and theoretical recommendations.

1. <i>Nekrasov K.D., Zhukov V.V., Gulyaeva V.F.</i> Heavy concrete at elevated temperatures. Moscow: Stroyizdat Publ.; 1972. (In Russian).

2. <i>Milovanov A.F.</i> Resistance of reinforced concrete structures in case of fire. Resistance of reinforced concrete structures in case of fire. Moscow: Stroyizdat Publ.; 1998. (In Russian).

3. <i>Schneider U.</i> Concrete at high temperatures - A general overview. Journal of Fire Safety. 1988;13(1):55–68. https://doi.org/10.1016/0379-7112(88)90033-1

4. SP 468.1325800.2019. Concrete and reinforced concrete structures. Rules for ensuring of fire resistance and fire safety. Moscow: Standartinform Publ.; 2020. (In Russian).

5. <i>Leonovich S.N., Litvinovsky D.A.</i> Analytical dependences of strength, deformative, force and energy parameters of high-strength concrete under heating. Vestnik BNTU. 2011;(4):30–34. (In Russian).

6. <i>Leonovich S.N., Litvinovsky D.A.</i> The fracture toughness of high-strength concrete after exposure to high temperature. Stroitel’nye Materialy = Construction Materials. 2017;(11):12–17. (In Russian).

7. <i>Kirchhof L.D., Lima R.C.A., Santos A.B., Quispe A.C., Silva Filho L.C.P.</i> Effect of moisture content on the behavior of high strength concrete at high temperatures. Matéria (Rio de Janeiro). 2020;25(1):e-12573. https://doi.org/10.1590/s1517-707620200001.0898

8. <i>Phan L.T., Carino N.</i> Mechanical properties of high-strength concrete at elevated temperatures [internet]. NISTIR 6726, National Institute of Standards and Technology; 2001. Available at: https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860330

9. <i>Yoon M., Kim G., Kim Y., Lee T., Choe G., Hwang E., Nam J.</i> Creep behavior of high-strength concrete subjected to elevated temperatures. Materials. 2017;10(7):781. https://doi.org/10.3390/ma10070781

10. <i>Diederichs U., Jumppanen U.M., Penttala V.</i> Behavior of high strength concrete at high temperatures. Report No. 92. Department of Structural Engineering, Helsinki University of Technology; 1989.

11. <i>Baranov A.O., Zorina E.A., Kirian I.V.</i> Mechanical Characteristics of High-Strength Concrete with Fly Ash and Silica Fume at Elevated Temperatures: The Influence of Heating Duration. Construction of Unique Buildings and Structures. 2021;96:9601.

12. <i>Poon C.S., Azhar S., Anson M., Wong Y.L.</i> Comparison of the strength and durability performance of normal- and high-strength pozzolanic concretes at elevated temperatures. Cement and Concrete Research. 2001;31(9):1291–1300. https://doi.org/10.1016/S0008-8846(01)00580-4

13. State Standard 10180 -2012. Concretes. Methods for strength determination using reference specimens. Moscow: Standartinform Publ.; 2012. (In Russian).

14. State Standard 24452-80. Concretes. Methods of prismatic, compressive strength, modulus of elasticity and Poisson’s ratio determination. Moscow: Standartinform Publ.; 2008. (In Russian).

15. SP 63.13330.2018. Concrete and reinforced concrete structures. General provisions. SNIP 52-01-2003. Moscow: Standartinform Publ.; 2019. (In Russian).

16.