Blast-resistant glazing: how it protects buildings from explosions

The words "glass" and "glazing" encompass many products, functions and materials. One key example of this is glass built to protect buildings against particular forces.

This could be safety glass (toughened or laminated) that resists impact. It could be fire-rated glass that prevents the spread of fire. Or, to take the topic of today's guide, it could be blast-resistant glazing.

This is a specialised type of safety glass engineered to withstand the shockwaves, pressures and flying debris created by explosions.

Before we go any further, it's important to note that blast-resistant glazing is more than just glass. To be classed as blast-resistant, the frame needs to be blast-resistant too.

Here at Wrightstyle, we provide clients in a range of sectors with blast-resistant glazing systems for curtain walls, screens, doors, windows and partitions.

In this article, we take a close look at how blast-resistant glazing systems are made and used.

How do blast-resistant glazing systems work?

Blast-resistant glazing systems absorb and dissipate the kinetic energy created by explosions. This means the glass remains safely secured inside its frame rather than exploding into dangerous fragments.

These kinds of glazing systems play a critical role in defending buildings against explosive attacks. They're widely used in settings where extra protection is required. Common settings include government buildings, embassies, airports and banks.

Why is blast-resistant glazing used?

The main purpose of blast-resistant glazing is to protect buildings from explosions. It does this in three ways:

Retaining fragments

Mitigating spall (chips and flakes)

Ensuring the integrity of the building envelope

When blast-resistant glazing is absent, an explosion shatters standard window glass into lots of harmful pieces.

These are often the main cause of secondary injuries and even fatalities in explosions.

Blast-resistant glazing is designed to fracture but keep the shards safely bonded together. In this, it closely resembles laminated glass – and, indeed, laminated glass is the primary type of glass used in blast-resistant glazing systems.

Related to this mitigation of flying shards is the way that blast-resistant glazing mitigates "spall". This refers to the tiny glass fragments that can be knocked off the glass in the event of an explosion.

And because the glass is designed to stay within its frame, the glazing prevents the blast of air created by the explosion from entering the room or building. This prevents the interior from collapsing and protects building users from eardrum ruptures and lung injuries.

How is blast-resistant glazing made?

A blast-resistant glazing system is more than just a sheet of laminated glass. Its protective capacity comes from three components.

1. Laminated glass

The infill of blast-resistant glazing systems usually consists of many layers of glass, as well as flexible polycarbonate. These are bonded under high levels of heat and pressure with plastic interlayers. These interlayers are often made from polyvinyl butyral (PVB) or SentryGlas (SGP).

The way they're constructed means that when the outer layers crack under explosive force, the plastic layers stretch and absorb the blast while simultaneously holding the broken shards in place.

2. Heavy-duty framing

Glass alone doesn't make a glazing system. Blast-resistant glazing systems also need heavy-duty frames and gaskets (seals). These ensure the frame stays in place when the glass flexes during an explosion.

These frames and gaskets can be made of aluminium or steel. Here at Wrightstyle, all our glazing systems are made from steel. This is because of the inherent strength of steel and its suitability for large-span and blast-resistance applications.

3. Robust anchorage

Finally, a blast-resistant glazing system needs robust anchorage. The frames need to be securely anchored into the walls of the building. Without this anchorage, the frame could be blown into the building.

What are the main uses of blast-resistant glazing?

An explosion could happen anywhere. Blast-resistant glazing, however, tends to be used in applications where the risk of explosions is magnified. This is why it's so commonly installed in governmental and military facilities.

In these settings – as in all its applications – blast-resistant glazing systems are used to minimise injuries and maintain structural integrity. In the case of embassies, defence buildings and military sites, they're designed to protect against terrorist attacks.

Blast-resistant glazing systems can also be found in industrial infrastructure – places like petrochemical refineries, offshore platforms, power plants and laboratories. This is primarily to protect against accidental explosions.

Transport hubs like airports and railway stations often have blast-resistant glazing systems to protect against terrorist attacks and other explosions.

The same goes for commercial buildings that require high levels of security. These include banks, corporate offices and even data centres.

How is blast-resistant glazing tested?

Blast-resistant glazing is tested under simulated explosive blasts. These can be via air-blast shock tubes or open-air arena tests. In both cases, the blast-resistant glazing is tested to see how it withstands overpressure, retains glass fragments and maintains structural integrity.

Standards used to measure blast resistance in glazing systems include ASTM F1642, ISO 16933 and EN 13451.

At Wrightstyle, all our glazing systems are subjected to real-world tests rather than simulations. In this video, we're testing a multi-paned blast-resistant curtain wall.

What we offer

Here at Wrightstyle, we offer high-quality blast-resistant glazing systems. They come in a wide range of design details and have been comprehensively tested to meet international standards.

Our SG series of blast-resistant curtain walls isn't just highly protective. It also has narrow 60mm sight lines, meaning you get all the benefits of blast resistance without a bulky profile.

We also offer blast-resistant doors, windows and fixed lights as part of our 60 series. These offer framing depths of up to 180mm with slim 60mm profiles.

Are you looking for high-quality blast-resistant glazing? Get in touch with our UK technical team today. We're ready to support you with step-by-step technical advice and in-depth product knowledge.

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