MECHANISMS OF INTERACTION BETWEEN REINFORCEMENT AND CONCRETE: CURRENT RESEARCH STATUS AND TECHNICAL ASPECTS

Abstract

The article presents a systematized classification of the types of bond between reinforcement and concrete, covering three main mechanisms: adhesive, frictional, and mechanical. It is shown that the greatest contribution to the total bond strength—up to 75%—is provided by mechanical interlock, caused by the ribs on the reinforcement interacting with the concrete through compression and shear forces. This supports the conclusion that using deformed bars without additional anchorage is a technically justified solution. The study reviews the findings of numerous national and international researchers, allowing the identification of key factors influencing bond parameters: concrete class and composition, type and diameter of reinforcement, anchorage length, curing conditions, type of aggregate, use of coatings, and methods of compaction. The comparative analysis demonstrates that increasing the strength of concrete up to a certain level leads to a linear rise in bond strength, while further increases result in diminishing returns. Research has shown that reducing the reinforcement diameter, using finer aggregates, and applying modifying admixtures can enhance bond strength, especially in lightweight concrete mixtures. Experimental results from other researchers confirm the effectiveness of epoxy, sand, and cement coatings for plain bars, which significantly improve their performance, bringing them closer to that of ribbed bars. It is noted that increasing the anchorage length does not always lead to improved bond strength, due to the uneven distribution of stresses along the embedded length. The conducted analysis confirms the necessity of a comprehensive approach to the study of bond behavior, taking into account the physicochemical and structural interactions. The obtained results have practical significance for improving the durability and crack resistance of reinforced concrete structures, particularly when using lightweight and modified concretes.