In the built environment, it is often assumed that a well-designed reinforced cement concrete (RCC) structure will comfortably last 50 to 75 years or more. However, reality can be far more complex. A recent structural audit led by our team at IIT Bombay, of a 20-year-old ground plus two-storey RCC building revealed alarming levels of distress, despite its relatively young age. The findings not only questioned the long-term durability of the structure but also spotlighted broader challenges in construction quality, environmental exposure, and maintenance culture. This case presents a compelling opportunity to reflect on how the absence of preventive care and environmental foresight can sharply curtail the lifespan of even modestly scaled concrete structures.

The building is a G+2 reinforced concrete structure located in an environment close to the sea. The structure was designed with extended corridor spaces functioning as communal passageways. From a usage standpoint, the building was unexceptional. Yet, in just two decades, it displayed symptoms more typical of structures twice its age. The core issues identified included:

• Extensive seepage from the roof and walls
• Significant corrosion of reinforcement bars
• Lack of maintenance, both structural and cosmetic

These issues triggered a rapid and alarming deterioration trajectory, particularly under an aggressive microclimate that was not accounted for during the design phase. The signs of structural damage were visible and pervasive:

• Vertical cracks across most peripheral columns
• Longitudinal beam cracks
• Spalling of concrete in large segments of slab surfaces
• Warped tiles, uneven flooring, visible slab deflections
• Persistent seepage and leaking, coupled with a completely degraded waterproofing system

The distress was not superficial. It extended deep into the structural core of the building.

To evaluate the true health of the building, a large number of non-destructive tests (NDT) were conducted, including: rebound hammer, ultrasonic pulse velocity (UPV) test, carbonation test, half-cell potential measurement, core sampling and chemical analysis, rebar scanner/cover meter testing. Beta test prototype of Nirixense Technologies CS 100 was used for cover meter testing. The results painted a grim picture:

• Concrete grading ranged from doubtful to poor
• Significant carbonation depth, indicating carbonation-induced corrosion
• High chloride content, accelerating rebar corrosion
• Lack of cover depth, compromising structural durability
• Widespread steel reinforcement corrosion, reducing load-bearing capacity

The residual quality of concrete and steel reinforcement was unequivocally unsatisfactory.

The building was never given a fair chance to last. The deterioration was not the result of one flaw, but rather a convergence of inferior construction quality, environmental exposure, and maintenance failure:

• Repeated wetting-drying cycles in high-humidity environment led to microcracking and chloride ingress
• Chloride ions and carbonation compromised the passive film on steel, triggering accelerated corrosion
• Lack of periodic maintenance allowed these issues to progress unmitigated over years

While technically feasible, the scale of specialized retrofitting and repair needed to restore structural integrity was enormous and economically impractical. Proposals for electrochemical rebar protection, passive cathodic protection system, high-performance concrete overlays & FRP based retrofitting, systemic waterproofing upgrades etc. were evaluated but deemed too costly relative to the building’s utility, age, and current state. After comprehensive analysis and deliberation, the prudent course of action was determined to be to demolish and rebuild.

This case brings forth critical takeaways for structural engineers, policymakers, builders, and owners alike:

• Durability begins at design: Exposure conditions, waterproofing needs, and future maintenance access must be factored early in the design process.
• Regular monitoring is essential: Minor seepages, cracks, early signs of corrosion must not be ignored. Preventive maintenance saves money and life.
• NDT-based audits should be routine: Early diagnosis beginning from the construction stage through modern NDT methods can delay, or even avoid, catastrophic degradation.
• Environment-specific strategies are non-negotiable: Coastal, humid, or industrial settings demand more aggressive protection mechanisms against carbonation and chloride attack.

If you’re involved in infrastructure lifecycle planning, consider integrating structural health monitoring (SHM) systems alongside NDT-driven structural audits and predictive maintenance protocols. Together, they enable a data-informed asset management approach, facilitating timely interventions, extending service life, and enhancing long-term structural resilience.

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About the Author: Dr. Sauvik Banerjee is Co-founder & Director at Nirixense Technologies, and Professor at Department of Civil Engineering, IIT Bombay. His experience includes structural health monitoring, using wave propagation and vibration-based approaches, quantitative nondestructive evaluation of structures, nondestructive testing, modelling of advanced composite structures, structural retrofitting and impact response of structures. He obtained Ph.D. degree from UCLA (Mechanical Engineering, 2003), M.Tech. from IIT Bombay (Civil Engineering, 2001).

Note: This article presents the author’s personal views and insights drawn from publicly shareable aspects of research and consultancy projects conducted as a faculty member at IIT Bombay. The content is intended solely for thought leadership and knowledge sharing. The views expressed do not necessarily represent those of IIT Bombay.