Challenges With Precast Concrete in Modular Blast-Resistant Buildings

This blog post was also published in the July/August issue of BIC Magazine. It is published here, in its longer, complete format.

Modular blast-resistant buildings offer exceptional protection in high-risk environments like oil and gas refineries. They set the bar for industrial protection projects when it comes to speed of construction, flexibility and scalability, cost-effectiveness, safety and more. Traditionally, steel has been the material of choice for modular blast-resistant buildings, but recently, there’s a new entry in the industry worth examining—the precast concrete modular blast-resistant building.

Even among steel blast resistant buildings, there are differences among manufacturers. Indeed, not all steel blast-resistant buildings are created equal. Now, it’s time to give critical consideration to the choice of materials used for modular blast resistant buildings manufacturing and the challenges that come with each choice.

In this blog post, we'll look at the intricacies of using precast concrete in modular blast resistant buildings. We'll explore the nuanced problems like electrolysis-induced rebar corrosion, moisture management issues, structural integrity concerns, and maintenance complexities that could accompany precast concrete structures. We'll contrast thconat with the robust and resilient nature of steel modular blast resistant buildings to guide industry professionals in making informed decisions when selecting a blast-resistant building solution, ensuring safety, efficiency, and longevity.

The Problem of Electrolysis in Concrete Blast Resistant Buildings

Electrolysis emerges as a significant challenge in any reinforced concrete structure. This is no less true in modular blast-resistant buildings. In this example, electrolysis problems would be due to the very thing that gives concrete strength: the addition of rebar.

Electrolysis occurs when dissimilar materials, in this case, concrete and the steel rebar within, are in contact with an electrolyte (moisture being a common one). This contact sets off an electrochemical reaction that leads to the generation of an electric charge. Unfortunately, this process results in accelerated corrosion of the rebar.

Rebar corrosion is not uncommon and can be observed in structures like bridges, where rust stains seeping out of concrete are often the first visible sign of underlying damage. By the time these signs are noticeable, the integrity of the rebar has been significantly compromised, necessitating extensive and costly repairs. This situation in a blast-resistant building could have grave implications, particularly when considering the building's primary function to withstand explosive forces.

Electrolysis and The Deterioration of Structural Integrity

Rebar corrosion is more than just a surface-level issue; it strikes at the very heart of a building's structural integrity. As rebar weakens due to rust, its ability to reinforce the concrete diminishes significantly. This degradation is particularly critical in blast-resistant buildings, where every component's strength and resilience are critical to the structure's overall performance and safety. Weakened rebar means that the building is less capable of withstanding the blasts it is designed to resist, posing a serious concern over time.

External damages are easy to spot during regular inspections. One of the most insidious aspects of electrolysis-induced corrosion is that it happens out of sight within the concrete. By the time visible signs like rust become apparent, significant damage has already occurred. This hidden decay presents a unique challenge, as regular inspections may not easily reveal the extent of the problem, leading to potentially undetected safety risks.

Comparative Perspective: Steel vs. Concrete

When it comes to comparing steel vs. concrete, the maintenance and inspection of concrete blast-resistant buildings need to account for the possibility of hidden rebar corrosion, with possibly more invasive and frequent checks, adding to the maintenance burden and operational costs. In contrast, steel modular blast-resistant buildings do not face issues like electrolysis. The uniformity of material (steel) eliminates the condition for electrolysis to occur, ensuring a more consistent and long-lasting structural integrity. The absence of such concerns simplifies maintenance and ensures consistent performance with less intensive upkeep.

Moisture Challenges in Precast Concrete Blast Resistant Buildings

Another potential problem with precast concrete modular blast-resistant buildings is managing moisture. Concrete, despite its appearance of solidity, is somewhat porous. This characteristic becomes a significant concern in humid and wet conditions, when concrete acts like a sponge, absorbing moisture. This increases the internal humidity levels of the building and could necessitate an enhanced dehumidification component in the HVAC systems. The additional demand for humidity control not only elevates operational costs but also complicates the overall maintenance of the structure.

The absorbed moisture in concrete blast resistant buildings can harm the adjacent finished materials. In an environment where concrete walls are consistently damp, materials like drywall, carpeting, and tile will suffer unless they are specially designed to be water or damp-resistant. Moisture leads to the degradation of these materials, causing aesthetic and structural issues and potentially leading to more frequent and costly repairs and replacements of these internal elements.

Roofing and Seam Leakage Concerns in Precast Concrete Modular Buildings

Another critical aspect is the integrity of roofing and seams in precast concrete buildings. Unlike steel modular buildings, where engineered seams are designed for tightness and leak prevention, concrete structures, especially those composed of multiple sections, could be prone to leakage. The process of creating these buildings involves pouring concrete into a form. Once cured and the forms removed, the resulting surface can be irregular and not precisely machined. These irregularities can lead to leaky roof seams, a challenge that is compounded in multi-section buildings.

The Challenge of Maintenance and Sealing in Blast-Resistant Buildings

Maintaining watertight and airtight seals in concrete blast-resistant buildings is a complex task. In steel modular buildings, for instance, merging multi-section units involves compressing a gasket and applying mastic or caulk, which is relatively straightforward due to the machined surfaces. However, in the case of precast concrete modular buildings, the irregular surfaces of concrete pose significant challenges. Ensuring a robust seal in such conditions requires meticulous maintenance and frequent reapplication of sealants, raising concerns about long-term durability and the need for constant upkeep.

With the potential for leaky roofs in multi-section buildings, the maintenance demands (and, in turn, structural integrity) are also a challenge. Maintaining a watertight seal in precast concrete blast resistant buildings becomes an ongoing challenge that you wouldn’t otherwise have. This raises questions about the long-term durability and the continuous need for upkeep in concrete structures.

An important consideration for owners of concrete blast-resistant buildings is their role in maintaining the building’s integrity. Regular checks and resealing efforts are necessary to ensure the continued effectiveness of the seals. This maintenance demand can lead to increased costs and resource allocation over the building’s lifespan, potentially making concrete blast-resistant buildings less desirable from a cost-efficiency standpoint.

Comparative Perspective with Steel Modular Blast Resistant Buildings

Contrastingly, steel modular blast resistant buildings offer a more controlled environment. The inherent properties of steel, coupled with advanced construction techniques, significantly reduce the likelihood of internal dampness. This leads to a drier, healthier, and more comfortable interior atmosphere. In steel modular blast resistant buildings, the risk of mold and fungus growth is substantially mitigated, ensuring a safer and more pleasant environment for occupants.

The Impact of Moisture on Building Components

The moisture issues prevalent in precast concrete modular blast-resistant buildings extend beyond structural concerns and have profound implications for the building's components, like electrical systems, components and equipment. 

In any industrial setting, the reliability of electrical systems is a chief concern. Concrete blast-resistant buildings, with their potential moisture issues, pose a threat to these systems. Think about the computers, servers, transformers, UPS panels, and other electrical components that might be present in daily operation. Persistent dampness is detrimental to this sensitive equipment. The presence of moisture can accelerate corrosion, short-circuiting, and other forms of damage, compromising the efficiency and lifespan of critical systems. For facilities that rely heavily on electronic equipment for operations, this can increase maintenance costs and potential operational downtime.

Moisture in the environment of a concrete blast-resistant building also affects insulation materials, potentially reducing their effectiveness. This can increase energy costs as heating and cooling systems work harder to maintain optimal temperatures. Furthermore, the damp conditions may expedite the degradation of various building materials and finishes, impacting the building's overall longevity and aesthetic appeal.

Comparative Advantage: Concrete vs Steel Modular Blast Resistant Buildings in Internal Moisture and Degradation

Because steel modular blast resistant buildings offer a more controlled and dry environment, electrical and mechanical components are safeguarded from moisture-related damage. The inherent properties of steel, combined with advanced construction techniques, create a barrier against moisture ingress, ensuring the protection and longevity of equipment housed within. This comparison of steel vs concrete translates to fewer maintenance issues, longer equipment life, and more consistent operational efficiency, highlighting the superiority of steel in maintaining a healthy environment for sensitive equipment.

Mechanical Connections and Structural Integrity in Concrete Blast Resistant Buildings

One critical aspect of precast concrete modular blast-resistant buildings that should be discussed is the mechanical connections that hold these structures together and their implications for structural integrity.

Concrete blast-resistant buildings, especially those comprising multiple sections, rely on mechanical connections to maintain structural cohesion. These connections are crucial in ensuring the building can withstand everyday stresses and the extreme forces of blasts for which it is designed. However, the nature of these connections in concrete structures may not offer the same refinement or strength as in other construction methods.

For example, let’s examine a common mechanical connection method used in precast concrete that is similar to the way hanging a wall painting works, where the head of a screw fits into a hole and slides into a smaller area to secure the picture. To remove the picture, you need to lift it and slide it off. While a similar mechanism may be adequate for nonstructural components, the question arises whether such simple connections can reliably sustain the intense demands placed on blast-resistant structures.

Comparative Perspective with Steel Modular Blast-Resistant Buildings

Steel modular blast-resistant buildings utilize precision-engineered connections and dynamic load transfer to ensure that even if the majority of pressure is applied to the building joints, there is overall structural integrity between sections of the building. The precision in steel construction allows for a more controlled and predictable performance under blast conditions, offering greater reassurance of safety and durability.

Steel Modular Blast-Resistant Buildings: Enhanced Structural Integrity and Precision

Steel modular blast-resistant buildings offer remarkable structural integrity, primarily due to the precision of their construction. The steel components are engineered and machined to fit together seamlessly, creating a uniform and robust structure. This precision contributes to reliable blast resistance and ensures long-term durability and stability.

Reduced Maintenance and Improved Longevity

Steel modular blast-resistant buildings' maintenance demands are significantly lower than their concrete counterparts. The absence of issues like electrolysis-induced rebar corrosion and moisture absorption inherent in concrete reduces the need for frequent inspections and repairs. This translates to improved longevity and reduced lifecycle costs, making steel modular blast-resistant buildings a more cost-effective solution in the long run.

Versatility in Design and Application

Steel modular blast-resistant buildings also offer versatility in design. For instance, in projects requiring elevated structures, such as those near waterfronts, steel blast-resistant buildings provide an efficient and feasible solution. Steel blast-resistant buildings have proven their adaptability in diverse environments and applications, which can be a critical factor in project planning and execution.

Addressing Fire Safety Concerns of Steel Blast-Resistant Buildings

Addressing fire hazards is a critical aspect of any construction material choice, particularly in the industrial sector, when hazards are present. In this context, it’s important to compare the fire safety features of modular blast-resistant buildings.

Precast concrete blast-resistant buildings are often lauded for their inherent fire resistance, primarily due to the nature of concrete itself. Concrete can withstand high temperatures and provides a good level of protection against fire spread. 

Modular steel blast-resistant buildings offer inherent protection against flash fires and require a more proactive approach to fireproofing in areas where jet or pool fires are a danger. This challenge is effectively addressed through the application of intumescent coatings and other fireproofing materials that provide steel structures with a high degree of fire resistance. These measures ensure that steel blast resistant buildings meet and often exceed the required safety standards for fire protection.

Balancing Fire Safety with Other Structural Requirements

While fire resistance is an essential factor, it should be considered alongside other structural requirements, such as blast resistance and structural integrity. Steel modular blast-resistant buildings provide a balanced solution, offering robust fire protection without compromising other critical safety aspects.

The Verdict on Modular Blast-Resistant Buildings

As we wrap up this exploration of modular blast-resistant buildings, it's clear that the material choice is not just a matter of preference but a critical decision impacting safety, durability, and operational efficiency. The in-depth analysis of precast concrete blast-resistant buildings reveals significant challenges – electrolysis-induced rebar corrosion,  moisture-related issues and maintenance complexities. These challenges highlight the inherent limitations of using concrete in such high-stakes applications.

Steel modular blast-resistant buildings stand out for their robust design, resilience, engineering excellence and reliability. They offer structural integrity, lower maintenance needs, and superior adaptability – qualities essential in environments where safety and efficiency are non-negotiable.

RedGuard has been at the forefront of blast safety since the early days, constantly refining its steel modular blast-resistant buildings to meet the evolving needs of the industry. When you choose a RedGuard steel blast-resistant building, you invest in a solution that guarantees reliability, safety, and peace of mind.

The future of blast-resistant construction lies in innovative solutions that combine safety with sustainability. RedGuard consistently meets its customers at this pivotal junction.

The RedGuard team is dedicated to providing expertise and solutions that align with your safety goals and operational needs. Together, let's build a safer, more efficient, and sustainable industrial future with steel modular blast-resistant buildings at its core.

To discuss your mitigation plan for hazards on your worksite, contact RedGuard. You can even email us and set a meeting with the writer of this blog post, Eric Rienbolt.