Chemical degradation and rehabilitation of concrete structures

Abstract

Concrete is one of the most widely used structural materials in modern infrastructure, yet long-term environmental exposure and internal chemical reactions can gradually degrade its internal microstructure and structural performance. Chemical degradation mechanisms such as carbonation, sulfate attack, alkali–silica reaction, and chloride ingress alter hydration products within the cement matrix, modify pore structure, and promote the development of microcracking within concrete. Although these reactions originate at the microscopic level, their effects propagate through structural elements by reducing stiffness, increasing permeability, and influencing cracking behavior and dimensional stability. Understanding how these degradation mechanisms affect structural performance is essential for evaluating the condition of existing concrete structures and selecting appropriate rehabilitation strategies. This report examines the relationship between chemical degradation mechanisms in concrete and structural rehabilitation techniques used to preserve deteriorated structures. The discussion first investigates the chemical processes responsible for deterioration and the environmental conditions that influence their development within the cementitious matrix. The structural implications of these degradation mechanisms are then evaluated, including their effects on stiffness degradation, tensile cracking, volumetric expansion, and transport properties within structural concrete. Following this evaluation, several rehabilitation approaches are examined that address both the chemical and structural consequences of deterioration. Migration control techniques, including carbonation barrier coatings, hydrophobic impregnation, and pore structure densification, are discussed as methods for limiting the transport of aggressive agents through the concrete pore network. Neutralization treatments such as lithium nitrate application and electrochemical realkalization are examined as approaches for modifying the chemical environment within the concrete to stabilize ongoing reactions. Structural repair methods including epoxy injection, stitching, post-tensioning, autogenous healing, and fiber-reinforced polymer strengthening are also considered for restoring load transfer, improving stiffness, and enhancing the structural performance of degraded concrete elements. Through the evaluation of degradation mechanisms and corresponding rehabilitation techniques, this report demonstrates how deteriorated concrete structures can be stabilized and preserved while maintaining their structural integrity. Understanding the interaction between chemical deterioration processes and structural repair strategies allows engineers to extend the service life of existing infrastructure and develop effective rehabilitation solutions for aging concrete structures.