CONTROL OF HEAVY CONCRETE CHARACTERISTICS AF-FECTING STRUCTURAL STIFFNESS

Abstract

New experimental data have been obtained on the strength and deformation characteristics of heavy concrete o strength classes B30-B100 (strength from 36.2 to 115.1 MPa), prepared from self-compacting mixtures using crushed stone from various dense rocks as a coarse aggregate - granite, basalt and gabbro-diabase, as well as crushed stone from gravel.

It has been established that the values of the compressive strength of concrete "R_bn" (prism strength) are 24% higher than the normalized indicators given in Table 6.7 of the current set of Building Code of the Russian Federation SP 63.13330.2018. For high-strength concrete on crushed granite of strength classes from B70 to B100, the values of the static modulus of elasticity E_b, which largely determines the stiffness of reinforced concrete structures, exceed by 5-14% the values given in Table 6.11 of SP 63.13330.2018. At the same time, the use of gabbro-diabase or basalt crushed stone as a coarse aggregate instead of granite does not affect the strength and Poison’s ratio. However, this allows increasing the static modulus of elasticity of concrete by 9 and 19%, respectively. The values of the dynamic modulus of elasticity of heavy concrete are in the range from 41.1 to 60.4 GPa and exceed the static modulus of elasticity of concrete by 2.2-5.3 GPa depending on the classes of concrete. The paper shows the possibility of using a less time-consuming method for monitoring the values of the static modulus of elasticity of concrete in structures by determining the dynamic modulus using the calibration dependence E_b - E_d.

The obtained results indicate that the real potential of high-strength concretes is not fully used in structures designed in accordance with normative characteristics R_bn and E_b provided for by SP 63.13330.2018. The actual values of these characteristics are higher and can be controlled by technological tricks.