| | Ordinary concrete with stone aggregates is the construction material widely used today worldwide for building various types of structures, from small to large. In large structures with significant spans, such as concrete bridges or high-rise buildings with substantial masses, it is particularly crucial for the concrete to possess good quality and reliable compressive strength. There are justified doubts raised by the author1 of this paper, regarding the accurate and precise determination of compressive strength in concrete worldwide [1],[2].Furthermore, authors doubts and argues that the compressive strength of concrete (σ= MPa) at the proportional point ( σp = MPa) is significantly lower, amounting to only 10% to 15% instead of 33% ( σp= MPa) of the value of ultimate compressive strength (σm,k = MPa), as it is currently interpreted in theory and practice worldwide. The first reason for doubt is the fact that the ultimate compressive strength (σm,k = MPa) of the same concrete type depends on the size and volume of the test specimens being examined [3], [4], [5]. This suggests that the compressive strength of concrete (σm = MPa) is relative, which cannot be acceptable from technical and legal perspectives [2], [1].Our research, examines three different sizes of cylindrical test specimens, with heights of 15 cm, 21 cm, and 36 cm, and a cylinder diameter three times smaller than its height. This research confirms the justified doubt and demonstrates that the ultimate compressive strengths of concrete (σm,k = MPa) are relatively uniform, regardless of the cylinder size, and on average, they are lower by 23.27% compared to the currently calculated, presented, and adopted compressive strengths of concrete on standard specimens, which are 20x20x20 cm cubes [3], [4], [5]. |
