COMPARATIVE ANALYSIS OF RESEARCH OF ADHESION OF REINFORCEMENT WITH CONCRETE BY DIFFERENT TEST METHODS

Abstract

The essence of system analysis to solve adhesion problems is to represent a set of connections between stresses on the contact surface of concrete and reinforcement depending on many determining factors (concrete class, rod diameter, anchoring length, nature of the load, long processes, etc.). System analysis involves mathematical modeling, which allows to quantify the nature and degree of influence of individual factors on the coupling stress, and also, their cooperation.

The strength of adhesion of reinforcement to concrete is evaluated by the resistance of pulling or pressing the reinforcing rods hammered into the concrete. While pressing the reinforcing rod into the concrete, the strength of adhesion is higher than when pulling it out, because of the resistance of the surrounding layer of concrete to the transverse expansion of the compressed rod.

The obtained final regression equations can be considered as mathematical models for determining the ultimate adhesion stresses on the contact surface of concrete and reinforcement. The difference between the experimental values and the theoretical values obtained using mathematical models was 1.2% and 4.5%. This allows us to talk about the reliability of both mathematical modeling and experimental data.

The strength of concrete significantly affects on the method of determining adhesion stresses and get higher with increasing class of concrete. The ratio of adhesion stresses when pressing the reinforcing rod to the adhesion stresses when pulling out the reinforcing rod, respectively, was: for samples of concrete class C25 - 1.2, and for concrete class C70 - 1.8.