INFLUENCE OF ELEVATED SINGLE AND REPEATED TECHNOLOGICAL TEMPERATURES ON THE STRENGTH PROPERTIES OF HEAVY CONCRETE
DOI:
https://doi.org/10.31713/budres.v0i48.17Abstract
Heavy concrete is one of the main building materials used to create structures of various types, including structures that operate under technological heating conditions. The article presents the results of experimental studies of the influence of technological single short-term or long-term (low-cycle) heating on the behavior of heavy concrete under the action of short-term and repeated compressive loads.
A reliably estimated stressed-deformed state of structures and materials during design, in their operation under various operating conditions, makes it possible to meet technical, operational and economic requirements for them.
The problem of studying long-term processes in concrete and reinforced concrete consists of three tasks:
- Reliable study of all processes occurring in concrete and reinforced concrete during their operation and identification of all the numerous factors that influence their development.
- Disclosure of the essence of the course of these processes.
- Description of the course of processes using mechanics and mathematics in time under a variety of external and internal conditions and determination of their influence on the stressed-deformed state of concrete and reinforced concrete elements.
Experimental studies were conducted on concrete prisms aged 90 days. The average strength values were determined for at least three samples. The longitudinal and transverse average deformations of concrete were determined on the four sides of the prism using 1MIG indicators.
Loading of test specimens with axial external load was carried out on a universal press PSU-250. Heating of concrete specimens was carried out in single-section special-purpose thermal chambers with an automatic system for measuring and recording temperatures at 12 points of the chamber.
The values of the average strength of concrete determined under the action of short-term loading at a temperature of 200C were taken as reference. The strength of heavy concrete under the action of short-term compression was tested in a heated state to 60, 120, 200 and 3000C. Studies have shown that the strength of concrete at a temperature of 600C decreased by 4%, at a temperature of 1200C - by 20%, at a temperature of 2000C - by 28% and when heated to 3000C - by 36% of the initial average value of the strength of concrete established at a temperature of 200C. In the cooled state after heating to 120, 200 and 3000C, the strength of concrete decreased by 28%, 26% and 30%, respectively. It can be concluded that experimental testing of heavy concrete under random or constant (periodic) exposure to technological (elevated) temperatures negatively affects the strength, deformability of the material, and destructive characteristics.
