Interfacial Bond Strength in Concrete Structures

Interfacial bond strength governs the performance and durability of multi‐layered and repaired concrete systems, from bridge decks and pavements to high‐rise façades and containment structures. At its core lies the transfer of stress across the junction between an existing substrate and an overlay or repair material. This transfer is influenced by mechanical interlocking, chemical adhesion and frictional resistance, all of which depend on surface topology, material composition, curing conditions and environmental exposure. Optimising bond strength not only enhances load‐bearing capacity and crack control but also extends service life and reduces maintenance costs. Advances in adhesive formulations, surface preconditioning and non‐destructive evaluation have delivered more reliable design parameters, while numerical models now link microstructural phenomena with macroscopic performance. As infrastructure demands intensify worldwide, understanding and controlling interfacial phenomena remain essential to resilient, sustainable concrete practice.

Research from Nature Portfolio

Recent studies have introduced a hierarchical laser‐scanning methodology to compute three‐dimensional surface roughness parameters, yielding localised maps of microscale peaks and valleys that correlate strongly with bond strength in cementitious overlays. This approach offers standardised quantitative metrics beyond traditional 2D profilometry, enabling practitioners to optimise surface treatments prior to repair. In parallel, work on silane‐modified nano‐silica particles incorporated into two‐pack epoxy adhesives has demonstrated substantial gains in mechanical and pull‐out performance for steel rebar anchorage. Surface‐treated SiO₂ nanoparticles markedly improved tensile and compressive moduli of the adhesive matrix, resulting in 40–50 % higher pull‐out strength and enhanced adhesion energy. These innovations bridge gaps between molecular design and field‐scale applications, pointing towards next‐generation bonding agents for critical structural connections.

Research from all publishers

A comprehensive review of concrete‐to‐concrete composites has synthesised decades of research on overlay–substrate systems, emphasising the interplay of interface preparation, bonding agent chemistry, mix design and environmental factors such as temperature and humidity. Key findings highlight that tailored matching of overlay and substrate stiffness, combined with optimised casting and curing regimes, can achieve bond strengths exceeding 2 MPa in direct tensile tests, while also improving sustainability through reduced material usage. Another recent survey of cement‐based repair materials contrasts traditional Portland‐cement systems with alkali‐activated and polymer‐modified formulations, identifying fibre reinforcement, surface roughening and moisture control as effective means of boosting interfacial adhesion. Finally, experimental work on the influence of old concrete age, surface fractal dimension and freeze–thaw cycling has shown that increased interface complexity outweighs substrate age in governing bond durability under environmental attack. Incorporating ultrasonic diagnostics alongside relative dynamic modulus measurements has further enabled real‐time monitoring of interfacial deterioration, guiding maintenance interventions.

Interfacial Bond Strength in Concrete Structures publication trend

The graph below shows the total number of articles in interfacial bond strength in concrete structures across all publications each year (not limited to Nature Index journals).

Technical terms

Interfacial bond strength: The stress required to initiate or propagate separation at the boundary between an overlay or repair material and an existing concrete substrate.

Pull-off strength test: A method to measure tensile adhesion by applying a perpendicular load to a bonded coating or overlay until failure occurs at the interface.

Surface roughness parameters: Quantitative metrics (e.g. Ra, Rq) describing the amplitude and distribution of surface irregularities that influence mechanical interlocking and friction.

Fractal dimension: A statistical descriptor of surface complexity across scales, used to characterise multi-level roughness and predict adhesion performance.

Ultra-high-performance concrete (UHPC): A class of cementitious composite with very high compressive and tensile strength, low porosity and exceptional durability, often used for advanced overlays and structural repairs.

References

1. Interfacial bond in concrete-to-concrete composites: A review. Construction and Building Materials (2022).
2. New Method for Evaluating Surface Roughness Parameters Acquired by Laser Scanning. Scientific Reports (2019).
3. Achieving outstanding mechanical/bonding performances by epoxy nanocomposite as concrete–steel rebar adhesive using silane modification of nano SiO2. Scientific Reports (2023).
4. Cement-Based Repair Materials and the Interface with Concrete Substrates: Characterization, Evaluation and Improvement. Polymers (2022).
5. Influence of Old Concrete Age, Interface Roughness and Freeze-Thawing Attack on New-to-Old Concrete Structure. Materials (2021).