ABSTRACT

The current codes and standards provide a procedure for processing the results of concrete strength evaluation that are obtained only by direct methods with the use of standard samples. However, the accuracy rate of the direct methods for evaluating the performance of constructional materials, which is found in national standards, is analogous to that of indirect measurements. The codes and standards fail to account of the fact that in aggregate inaccuracy, the component relating to an indirect method of measurement can be significant. The actual instrumental error may largely distort testing results, leading to miscalculated structural reliability of projects under construction.

An example of concrete strength evaluation is given to illustrate how the accuracy of measured strength performance, with standard samples used in tests, affects the level of reliability of concrete and ferroconcrete structures. The inaccuracy of indirect method of measurements has been analyzed for its effect on test results and reliability of the construction projects. Evidence is given of the significant influence the methods for testing concrete performance have on the reliability and trouble-free operation of geotechnical structures and buildings in general. Practical measures are proposed that are designed to enhance the quality of construction products.