Sika Adhesives protect People and Property alike

Structurally glazed curtain walls are the state of the art. The use of silicone adhesives for structural bonding of glass panels to a metallic frame is a well-established technology in façade applications.

These adhesives meet the highest standards defined in ETAG or ASTM. But Sika adhesives meet more than just standards. Due to their elastic properties and high mechanical strength, this solution also withstand extreme conditions, meaning it can offer a high performance in this conditions.

Be it the temperature that may prevail on this globe, be it the wind load several hundred meters on the top of a building or caused by a hurricane or typhoon. Or by sudden heavy loads such as a bomb or an attempted burglary. Even in earthquakes, Sika adhesives can save lives and protect property.

At Sika, we know our products inside and out, and we help you and our customers take advantage of the excellent properties of this high quality product even under extreme conditions.

Burglar Resistant Windows

Windows and doors are the weak points in a building where forced entry should be prevented. With the right material and construction windows can be made burglar resistant meeting the requirements of the European standards and classifications.

Such window constructions are classified according to EN 1627 "Pedestrian doors, windows, curtain walls, grilles and shutters“ - Burglar resistance, Requirements and Classification. This comprises six classes of resistance: RC1 to RC6. They determine the duration this glass installations can resist the attempt of forced entry with different tools and different forces.

But even with the use of laminated glass and burglar-resistant hardware, one weak point remains - the possibility of levering the glass out of the frame.

The Sika Solution for Burglar Resistant Windows

Sika offers a range of tested and proven adhesives that offers a high quality for a tough elastic bond between the glass and the frame.

A burglar will have difficulties levering the glass out of the frame if glued for example with the easy-to-apply Sikasil® WT-66 PowerCure, a boostered one-component silicone adhesive.

Ask your local Sika representative for the optimal solution.

Smash and Grab burglar method

Increasingly, shops are using cashless payment transactions. The amount of cash in the shops is minimal and no longer attractive to burglars and thieves. This has driven the burglars to use the so-called “Smash & Grab” method.

A “Smash & Grab" is a special form of burglary in which vehicles are used to destroy the glass barrier, e.g., a shop window or a display, grab valuables and then make off quickly, notwithstanding setting off alarms or making noise.

Now the aim is that the façade element does not give way to the burglar attack. Achieving this goal with standard constructions, thick and heavy metal frames would be required, making the glass front very expensive and visually unattractive for architects and owners.

The Sika Solution for Smash and Grab burglar method

Sika adhesives help overcome this disadvantage. Glass bonding into the frame with high-strength adhesives hardly can be pulled out and the burglar no longer finds an opening for intruding the shop. Furthermore, the shop can be operated until the damaged glass has been replaced. It is fair to say: Sika Adhesives protect the life and property of the occupants.

Sika works closely with all renowned facade and window profile manufacturers. Most of them have developed profile systems successfully tested and well established that provides high performance against burglars. The Sika adhesive is always the key element, as elastic bonding absorbs a significant portion of the impact energy and forms an additional cushion zone.

For more information, please ask your Sika representative.

Explosion Scenarios for Glass Facades

An explosion, whether caused by a technical defect or by a malicious attempt to destroy life and property, is one of those events that occur very rarely. But when they do, they are totally devastating - to life and property.

But the glass facade can be a safety shield if properly planned and executed with the right materials. It can protect people and property in the building. Even if in worst case the building and especially the glass facade needs to be replaced after the explosion.

Usually fixed glass facades, if designed to withstand extreme forces from explosions, require massive frames, with negative effects both on cost and on appearance.

The Sika Solution for Explosion Scenarios

By bonding the glass units to the frame with a tough but elastic Sika adhesive, it becomes almost impossible to separate the glass from the frame during the explosion, thus preventing endangering people and destroying property. Furthermore, the business in the building can remain unaffected until the glass has been replaced. Here, Sika adhesives have a small effect on the cost, but a significant impact on the benefits. Again, it is fair to say: Sika adhesive protects the life and property of the occupants thanks to its high performance.

Sika has tested and successfully implemented solutions in construction projects, whether based on silicone or other technologies.

Properly selected elastic adhesives have sufficient strength to anchor and secure laminated glass to the frame. This adhesive is only one component among many other that can make a glass façade or window safe.

The performance of the system depends on many variables, such as the flexibility of the building element, the building element size, the type of laminated glass used, the design of the frame and how it is anchored to the building. Also is important to consider the glass installation.

The main function of an elastic bond is to hold the glass in the frame during the explosion. The use of laminated glass reduces the damaging effect of glass fragments entering the occupied areas of the structure. Without the use of a resilient, high quality structural adhesive, injury from bigger flying elements segments may occur.

Learn more about Explosion Scenarios

Requirements on the facade component (for Explosion Scenarios)

An explosion is a vast, spontaneous release of energy in the form of shock wave, light, heat and sound. The shock waves, consisting a highly compressed air travelling at supersonic velocity, hitting the building are reflected and even amplified.

The magnitude of the overall incident blast high pressure is a function of the charge weight and stand-off distance from the center of the charge to the wave front. Such a pressure decays rapidly and becomes negative in value due to vacuum created by the shock front resulting in suction. 

The performance of the Bomb Blast Mitigating System depends mainly on the frame structure, either steel or aluminum, and how much of the impact energy is absorbed by the building components.

In general, a more absorbent system is advantageous over a structure that is too stiff.

The common element of all these successful designs is the laminated safety glass (usually made of polyvinyl butyral - PVB). The purpose of laminated safety glass is to absorb the shock of the explosion by keeping it intact. The high quality glass will break but the fragments will remain largely attached to the glass panes.

Blast Wave
Obrázek: Explosion Blast Wave

Another common element used successfully in protective glazing systems is the elastic adhesives that must be used to keep the glass pane in the frame. Structural silicone adhesives are predominantly used as they offer the advantages of durable long-term adhesion to glass and frame, high strength and high flexibility

The strength offered by an adhesive depends on load duration. The shorter the load duration, the higher the strength. 

Performance of Sikasil® SG during explosion scenarios

In lap shear tests with high-speed impact at 4 m/s the reaction of adhesives to bomb blasts can be simulated. This is 60’000 times faster than the test speed at 5 mm/min acc. ISO 8339. The lap shear strength of the standard adhesive is 0.9 MPa at 5 mm/min and 2.8 N/mm2 at 4 m/s.

At this high speed the lap shear strength is more than tripled due to molecular reaction to the high impact speed. With 4.2 MPa the high-strength adhesive reached a much higher lap shear strength indicating their big potential in bomb blast resistant glazing. A higher test speed may result in even higher lap shear strength.

But this is not that relevant for the bomb blast reality as the glass pane reacts to the impact only with a maximum speed of about 4 m/s (slightly depending on the glass type).

Real explosion tests, undertaken at the GL Noble Denton test range at Spadeadam in Cumbria UK, have proven the lab results and impressively demonstrated the concept of elastic bonding in a bomb blast scenario. 

For the blast tests, generally in accordance with the test criteria set out in ISO 16933, an explosive of 100 kg TNT equivalent (using nitromethane explosive as the trial charge) has been used at a stand-off range of 25 m and 19 m respectively.

The test blasts clearly showed the positive effect of an elastic adhesive (Sikasil® SG-550).

No tearing of the glass panes out of the frame and no glass fragments inside the test box were observed, resulting in classification B (No Hazard according to ISO 16933:2007).

Strength increase due to dynamic impact simulation for Sikasil® SG-500 adhesive
Test speed Strength Multipliaction factor to the refrence value
Strength at 5mm/min 0.9 MPa Reference value with standard test speed according to ISO 8339 
Strength at 1 m/s 2.4 MPa  2.6 times higher
Strength at 3 m/s 3.1 MPa 3.4 times higher
Strength at 5 m/s  3.3 MPa 3.7 times higher

Ultimate concept for explosion scenarios – high strength adhesive 

Beside structural silicones, Sika also offer high-strength and high quality adhesives. These allow pushing further the load limits and optimizing the joint dimensions. Sika follow the logic outlined above and use technologies that are unparalleled on the market.

Additional to the next generation structural silicone as Sikasil® SG-550, the first high-strength structural silicone adhesive on the market. Sika offer the unique PU adhesive Sikaflex®-268 PowerCure.

The PowerCure dispensing and packaging platform combines two features. The ease of use of a 1-component adhesive application with the benefits of a 2-component adhesive application.

The PowerCure system is as powerful and reliable as industrial pump and dispensing systems. Sikaflex®-268 PowerCure consists of a moisture-curing 1-component adhesive accelerated by booster paste. It allows full cure no matter of air humidity.

Strength increase due to dynamic impact simulation for Sikaflex®-268 PowerCure
Test speed Strength Multipliaction factor to the refrence value
Strength at 5mm/min 4.5 MPa Reference value withs tandard test speed according to ISO 4587
Strength at 1 m/s 14 MPa 3.1 times higher
Strength at 3 m/s 39 MPa 8.7 times higher
Strength at 5 m/s 41 MPa 9.1 times higher

The higher the speed, the higher the adhesive strength

Sikaflex®-268 PowerCure is a PU adhesive widely used in the rail industry to structurally bond glass windshields and windows to frames of trains. Similar to façade applications, joints are exposed to:

  • High loads e.g. wind load, barrier loads, high impact loads e.g. tensile/pressure waves on high-speed trains entering tunnels)
  • High temperatures
  • Fatigue phenomena due to cycling loading
  • UV radiations
  • Weathering aging

Sikasil® SG-500

Sikasil® SG-550

Sikaflex-268 PowerCure

+ Excellent Weathering Resistance

+ Excellent Weathering Resistance

+ Long term adhesion on Glass and Frame

+ Long term adhesion on Glass and Frame

+ Fast strength development

+ Ultimate fast strength development

+ Excellent UV-Resistance

+ Minimal joint size at maximal performance 

- Mixing with defined ratio

+ Fail-Proof Mixing

- Limitations in joint size optimization  

- Requires UV Protection Measures on joint bite

Protective Glazing in case of Earthquake

There are about 10,000 seismic activities worldwide each year, some of which have a magnitude higher than 7. In regions where seismic activity is very likely, buildings must be constructed accordingly. The aim of the structural measures is to protect life and minimize damage to the building.

Unlike the usual forces such as wind load or even an explosion, the forces of an earthquake on a building arise from the inertia of the building's parts responding to the shifts in the ground. Some parts of the building may still comply, others may not. This results in friction, shocks and stresses that destroy individual parts of the building. In the worst case, the destroyed building parts fall out of and destroy other parts or even endanger human lives.

This circumstance can be particularly dangerous also with reference to the façades and even more glass façades. Falling glass elements endanger people in and around the building.

With mechanically fixed glass, there are very high risks that the glass hits the metal profiles during the seismic movements in the building structure. The fragile glass breaks and falls out of the frame.


The Sika Solution for Earthquake

When the glass is glued to the frame, an elastic connection is created that can absorb forces and protect the glass from peak stresses. In the worst case, laminated glass panels may shatter, but do not fall out of the frame and thus remain in the building structure. Falling glass is thus considerably minimized or even prevented.

Sika has developed engineering concepts for structural sealant glazing design in earthquake scenarios and tested and successfully implemented solutions in construction projects.

Ask your local Sika representative for the optimal solution

Learn more about Structural Silicone Glazing systems in seismic areas

Benefits offered by Structural Silicone Glazing (SSG) systems in seismic areas

For facade and architectural glazing design, two main issues related to the performance during and after an earthquake must be considered:

Human hazard - injuries and deaths at street level from broken glazing systems are recognized threats. Building downtime and repair costs - Restoration of normal operations and services may be hampered by a damaged building envelope.

The advantages of structural sealant glazing (SSG) systems over alternative glazing methods in terms of earthquake safety under real conditions are confirmed and recognized. Captured glazing systems in curtain walls consist of glass units that are mechanically fixed to a main frame. Loads acting on the glass units are mechanically transferred into the building via the frame.

In contrast, loads acting on the glass units in structural sealant glazing (SSG) systems are absorbed via structural and elastic silicones. This significantly reduces the risk of the glass being levered out of the frame and falling down during seismic activity.

The right adhesive, and therefore the right joint design, is critical to ensure the transfer of seismic loads and the absorption of seismic displacements between floors. However, Sika can meet this challenge by finding the optimal balance between cost and risk without compromising safety.

Benefits offered by slicones for structural glazing systems in seismic areas Captured glazing systems in seismic areas - mechanically fixed
+ Reduced risk of glass clashing to metal parts - High risk of contact between glass and frame and thus of glass breaking and falling out
+ Differential movements between glass and frame are absorbed by the SG joints - Differential movements between glass and frame lead to pressure forces on the glass unit with the risk of buckling of the unit or even pushing out of the frame.
+ Low risk of broken glass, thus the function of the facade is preserved as long as possible. Resilient behavior, with the joint retaining in position any broken glass  - Broken glass loses stiffness, the whole façade becomes unstable. 

Vertical differential movements between slabs

The upward and downward differential seismic movements of the slabs are usually accommodated by the vertical stack joint along the transoms; adequate vertical clearance should be designed to avoid clashing of the panels. Therefore, no significant differential movement is imposed to the SSG-joints by such vertical seismic movements.

Horizontal differential movements between slabs (out-of-plane component)

The out-of-plane differential seismic movements of the slabs due to inter-storey drift are usually accommodated by the brackets which should allow for free rotation of the panel. Therefore, no significant differential movement is imposed to the SSG-joints by such horizontal out-of-plane movements.


Horizontal differential movements between slabs (out-of-plane component)

The out-of-plane differential seismic movements of the slabs due to inter-storey drift are usually accommodated by the brackets which should allow for free rotation of the panel. Therefore, no significant differential movement is imposed to the SSG-joints by such horizontal out-of-plane movements.


Advanced engineering approach

Sika has developed an advanced engineering concept to design structural sealant joints in systems exposed to earthquake.
Three different performance levels are introduced. Each level deals with a different probability of occurance of the seismic event, different facade requirements as well as acceptable utilization level for the joints. Balancing costs and risks with no compromise on safety.
Contact Sika engineers for advanced support.



Sikasil SG-500 Silicone