The Engineering Choice: Why the Maldives Prefers Reinforced Concrete Over Prestressed Concrete

Prestressed Concrete. Photo Credits: No People Stock photos by Vecteezy

In the world of structural engineering, concrete has one fundamental flaw: while it is incredibly strong when you push on it (compression), it is weak when you try to pull it apart (tension). This is why standard concrete needs steel rebar—to handle the pulling forces that develop when a slab or beam bends under weight.

Prestressed Concrete (PSC) is a revolutionary step that solves this weakness before the structure ever sees a load. In PSC, high-strength steel tendons are stretched either before or after the concrete is poured. When released, the steel shortens, actively compressing the concrete, making the entire member stiffer, stronger, and far more resistant to cracking and deflection. This technology offers impressive benefits: longer, column-free spans, thinner slabs, and superior crack resistance.

We are writing this article because our clients often come to us with ambitious ideas, frequently asking, “Why can’t we use Prestressed Concrete? I hear it’s the best way to get a column-free space.” While PSC is an incredible technology, it is not always the best fit for every environment—and that’s a critical distinction to make. Given the unique and challenging construction environment of the Maldives, standard Reinforced Concrete (RC) is often the preferred and safest choice.

Here is an insightful look into why the Maldivian building sector largely avoids this high-tech solution:

The Core Difference: RCC vs. PSC

The distinction between Reinforced Concrete (RCC) and Prestressed Concrete (PSC) boils down to when the steel begins to work. RCC is a passive system: the cheaper, mild-steel rebar only engages and carries tension after the concrete has cracked under load. PSC is an active system: it uses more expensive, high-tensile steel tendons to introduce compression before any load is applied, aiming to be crack-free. While PSC allows for thinner, lighter structural sections and is ideal for long spans (over 15m), it comes with a high initial cost, requires specialized equipment (jacks and anchors), and demands highly skilled labor. In contrast, RCC is simpler, cheaper, uses common materials, and is perfectly suitable for the shorter spans (under 10m) common in Maldivian urban development. This trade-off between performance (PSC) and practicality (RCC) is the foundation of our local construction choice.

1. The Enemy is Salt: A Corrosion Catastrophe Waiting to Happen

The single most defining factor in Maldivian construction is its constant, unwinnable battle against high salinity. Prestressed concrete, while durable, introduces a severe point of failure in this scenario: the high-tension steel tendons. These tendons are thin, high-strength strands under immense tension. If saltwater penetrates the concrete (which it inevitably does near the shoreline), it can rapidly corrode these strands. Combining that corrosion with the locked-in tensile force creates a risk of sudden, violent failure that is exponentially higher than with standard rebar. The risk is simply too high when your building is perpetually being kissed by the ocean.

2. Complexity and Quality Control are Non-Negotiable

Prestressed systems demand impeccable construction quality, including absolutely perfect grouting and concrete cover to protect the delicate, high-tension tendons. Achieving this stringent level of quality control consistently across a nation of scattered islands is a daunting, expensive, and often unrealistic logistical challenge. Furthermore, the specialized knowledge required to design and execute prestressed work safely demands importing and retaining highly skilled labor. When you choose standard Reinforced Concrete (RC), you choose a methodology that is simple to execute, uses widely available materials, and tolerates minor imperfections far better than its stressed counterpart.

3. The Logistical and Cost Tax

Building in the Maldives is dominated by logistics because nearly all construction products must be imported. This is where the PSC cost truly balloons: every specialized item, from high-strength steel tendons to the hydraulic jacks and anchor systems used for tensioning, must be imported, incurring heavy freight, duty, and handling fees. This import necessity adds substantially to the already high construction cost. For the typical short-span, low-rise structures that make up the majority of the non-resort market, the small benefit of thinner slabs offered by PSC simply does not justify the massive upfront investment in specialized materials and the talent required to install them.

4. Prioritizing Safety Over Slenderness 

Prestressed concrete’s primary appeal is achieving long spans and ultra-thin slabs. However, because of the ever-present corrosion risk in the tropics, many local engineers will deliberately choose a thicker RC slab. This trade-off provides a greater, more robust concrete cover, offering superior long-term protection against saltwater intrusion and giving the structure a more predictable, robust lifespan. In the unforgiving tropical environment, the robust, low-tech, and predictable solution often beats the complex, high-maintenance one. The Maldivian construction philosophy often concludes that safer and simpler is far better than sleek and stressed.

A Look Ahead

While standard RCC currently dominates due to its simplicity and resistance to our harsh environment, Prestressed Concrete remains vital for unique applications. Landmark infrastructure projects, such as the SinaMalé Bridge and the ongoing Thilamalé Bridge, must utilize PSC to achieve their necessary long spans and performance characteristics. As the nation undertakes more ambitious, high-span developments and local expertise grows, we may well see this technology move from specialized infrastructure to more common commercial projects in the future.

Published on 01st December 2024 by The Project Solutions Team