Transition coefficients during bending testing of samples for mortars and fine-grained cement concretes

Abstract

Introduction. Existing cement mortars and fine-grained cement concretes have the same composition, however, according to State Standard, these materials are tested using different methods for evaluating physical and mechanical properties that are not in harmonious accordance with each other. This disagreement in the evaluation of properties confuses the regulatory authorities, which receive data that contradict each other. The introduction describes the appearance of discrepancies in the assessment of the properties of fine-grained cement concrete and cement mortar. A change in the concepts of definitions between the original classification and the modern one is presented.

Aim. Finding the transition coefficients when testing for three-point and four-point bending of samples of mortars and fine-grained cement concrete, taking into account the geometric dimensions of the samples.

Materials and methods. Preparation of cement concrete samples of various classes of materials conforming to State Standard requirements, description of differences in methods for determining three-point and four-point bending, calculation and manufacture of additional installations taking into account the geometric dimensions of the samples, conducting bending tests according to standard methods and using manufactured installations preserving the proportion of values taking into account the scale of the sample, as well as calculation of transition coefficients for each class.

Results. The results of the study showed that the transition coefficients have a significant impact on the processing of the results and the assessment of the strength characteristics of mortars and fine-grained cement concretes and may affect the accuracy of the data obtained.

Conclusions. The study provides a better understanding of the mechanical properties of mortars and cement concretes during bending, which can be useful in the design, construction of structures and quality control.