Whether architectural glass is safe cannot only be determined by how strong it is at ordinary times, but also by what will happen after it breaks. When the glass door is hit by a cart, the floor-to-ceiling window is hit by a hard object, the glass fence is hit by a human body, or the lighting roof is hit by a falling object, even if the glass cannot be completely unbroken, it is necessary to minimize the flying of large fragments and secondary risks caused by personal cuts and glass falling off. The main value of laminated glass is reflected after the glass is damaged.
Why is laminated glass more suitable for locations with higher safety requirements?
Laminated glass is usually made up of two or more pieces of glass laminated with an intermediate film. After heating, pressurizing and other processes, the glass and the intermediate film form a stable overall structure.
When the glass is impacted and breaks, the intermediate film can adhere to most of the glass fragments, making it difficult for the fragments to fall apart immediately. Compared to ordinary monolithic glass, laminated glass reduces the risk of sharp debris flying, falling and scratching people. ISO 12543-2 puts forward corresponding performance requirements for architectural laminated safety glass, while ASTM C1172 covers the quality and various application requirements of architectural laminated glass.
It should be noted that laminated glass does not "never break". Its safety logic is not simply to pursue not being broken, but to leave the fragments on the intermediate film as much as possible after damage occurs, and to maintain the coverage of the original glass area to a certain extent.
For locations where people are in frequent contact, where people pass under the glass, or where the glass plays a protective role, this ability to retain pieces after breaking is very important.
The main safety advantages of laminated glass：
1Reduce flying glass fragments
After ordinary glass breaks, it is easy to form sharp fragments of different sizes.
Debris may fall to the ground or fly around, causing cuts to nearby people.
After the laminated glass is damaged, most of the fragments will continue to adhere to the intermediate film and will not easily disperse immediately. Therefore, it is often used in glass doors, floor-to-ceiling windows, indoor partitions, schools, hospitals and public buildings and other locations where there is more activity. Technical data from the National Glass Institute also pointed out that after laminated glass is broken, glass fragments usually adhere to the intermediate layer and remain in the original opening area.
2.Reduce the risk of overall glass falling off
For glass railings, curtain walls, canopies and lighting roofs, whether glass fragments will fall from high places is more worthy of attention than whether cracks appear on the glass surface.
The sandwich structure can connect broken glass together, reducing the possibility of large amounts of debris falling directly. Especially in glass panels, compared with a single piece of tempered glass, laminated glass has a better chance of retaining debris in the support system after damage.
However, whether the glass can continue to remain in the frame is also related to the type of intermediate film, glass thickness, clamping method, fixing depth, glass size and stress. We cannot directly judge whether the entire railing or curtain wall system is safe just by using the name "laminated glass".
3.Reduce the risk of cuts after impact
Places such as shopping mall entrances, office partitions, floor-to-ceiling windows and glass doors of houses are prone to accidental collisions by human bodies.
Safety glass testing usually simulates a human body or a soft object hitting the glass to check for dangerous breakage of the glass. One of the testing purposes of ISO 29584 is to evaluate the safe breakage characteristics of architectural glass after being impacted by soft materials and reduce cutting and puncture injuries caused by accidental impact by personnel.
When selecting laminated glass, buyers should not only ask "whether it is safety glass", but should also confirm what impact test the product has passed, what level it corresponds to, and whether the structure of the test sample is consistent with the actual purchased product.
4.Buy processing time for temporary glass replacement
After the glass is broken, if the fragments are still attached to the intermediate membrane, the original hole will usually not be completely open as after a single piece of glass is broken.
In some doors, windows, partitions or building exterior enclosure applications, this can reduce the risk of direct contact with damaged edges, and can also gain processing time for setting up on-site alerts and arranging for glass removal and replacement.
However, the damaged laminated glass is no longer in normal use. The site should be closed in time and replaced by professionals. It cannot continue to be used for a long time just because the fragments have not fallen for the time being.
What is the difference between laminated glass and tempered glass?
Both tempered glass and laminated glass can be used for building safety glass, but the two solve different problems.
Tempered glass has high mechanical strength and temperature difference resistance. After rupture occurs, smaller granular fragments are usually formed, reducing the risk of ordinary glass forming large sharp fragments.
The focus of laminated glass is the adhesion and retention of broken fragments. Even if the glass has cracked, the intermediate film can still connect the fragments together.
Therefore, tempered glass pays more attention to the strength and broken form of the glass, and laminated glass pays more attention to the ability to retain pieces after damage. In applications such as railings, canopies, lighting roofs and high-rise glass, projects often use tempered laminated glass to combine heat-treated glass with an intermediate film.
However, tempered laminated glass cannot be simply understood as "tempered glass with a layer of film." The glass heat treatment method, intermediate film performance, glass edge quality and supporting structure all need to be designed based on actual loads.
Conclusion
The advantage of laminated glass is not only that it has an extra layer of intermediate film than ordinary glass, but it can change the state of the glass after it is broken.
When the glass is hit, whether the fragments can be retained, whether the hole will open immediately, and whether the glass will fall from a height are often more important than whether the glass cracks.
For glass railings, daylight roofs, floor-to-ceiling windows, glass doors and curtain walls projects, laminated glass can add an important safety protection to the building. But its actual effect depends on the glass configuration, intermediate membrane, support structure and installation quality.
Only by clearly specifying the location of use, risk level, implementation standards and complete product structure when purchasing can we choose laminated safety glass that is truly suitable for the project, rather than just comparing glass thickness and price per square meter.
