Light-flooded spaces and transparency in buildings are no longer just a trend in the architectural world, but are increasingly state-of-the-art. This transparency does not end with the balcony. Total vision glazing and glass balustrades can offer the continuity of wide open spaces, if they are not interrupted by framing or other mechanical fixations. When it comes to connecting glass to frame materials, Sika always rises to the challenge to find suitable solutions.
For total vision glazing and glass balustrades, the attachment of the glass panes to the floor is ideally concealed from the eye, leaving a barely visible, uninterrupted wall of glass. Glass grouting with cementitious grout has become a widespread, economic technology for balcony glazing, but many cases of breakage have been reported because of its hardness and high rigidity.
Furthermore, in the past few years, glazing regulations for balustrades have changed significantly. Laminated safety glass has replaced single monolithic glass with enormous consequences for glass grouting. As the cementitious grout is very aggressive against PVB interlayers, causing discolouration and milky areas, it is no longer a durable solution for glass grouting. Therefore, Sika has developed a compatible solution with selflevelling two-part polyurethane (PU) grouts.
With SikaForce-735 and SikaForce-730, the bottom glass edge is embedded in a U-shaped profile. The loads are securely transferred through the glass elements, resulting in uniform stress distribution. SikaForce creates a strong but flexible fastening solution, capable of withstanding the highest static and impact loads. It is ideal for horizontal glass-wall grouting jobs.
The mechanics and workability of SikaForce make it different to the alternatives offered in the market. Sika's glass embedding products offer just enough flexibility to take up some stress created by impact or thermal expansion. On the other hand, they are also rigid enough to prevent sway in the balustrade.
To prove this, the Laboratory for Steel and Light Metal Construction in Munich, Germany, has tested and certified SikaForce-735 and SikaForce-730 for accident proofing, based on the technical regulations for the use of accident-proof glazing. The products carry a German general building authority test report. The test comprised two 10.00mm tempered or heatstrengthened safety-glass panes with a 1.52mm PVB interlayer. The clamping depth of the glass pane was 100mm. The U-channel was made of 10mm steel and was very rigid in order to test the worst-case scenario. Impact tests were carried out with a pendulum, according to DIN EN 12600, with a dropping height of 700mm.
The installation of the glass panes is uniquely simple and economical. SikaForce-735 and SikaForce-730 are easily mixed on-site with a butterfly mixer. The long 'open' time of both products offers the applicator two methods of installation. In the first method, the PU grout is filled to a calculated level into the channel. Then the glass glides into its final position. A spacer tape at the bottom and at the edge of the glass keeps the distance between glass and support frame.
In the second method, glass is first positioned and fixed in the channel, ideally with wedges and setting blocks made of the PU grout for an optimal stress distribution. Then the PU grout is poured into the channel. SikaForce-730, with its low viscosity, is the ideal product here. With the second method, a clearance of 10.0mm between glass and channel is recommended, resulting in a grout volume of only 2.5L/m. With the first method, this volume can be further reduced, but the clearance on each side should not be less than 6mm. This low volume, together with easy applicability, makes the method a very competitive glass fixation technology, overall.
For stairs and inclined glass railings, Sika offers the non-sagging SikaForce-720 which has the same mechanical benefits and proven reliability. For an easy application on-site, this product is available in user-friendly two-part cartridges. In exterior applications, the PU grout is normally protected against UV radiation and weathering with a bead of Sikasil silicone sealants.
In the case of glass breakage, the panes can easily be replaced for repair work. The broken glass is removed first. After the glass pane is demolished with a hammer, the lamination interlayer is cut through with a knife. The embedding material and the glass is destroyed with a demolition hammer and lifted out with a crowbar. Finally, the support frame is cleaned thoroughly to remove dust, glass debris and embedding material. The use of a release agent on the channel and the glass, before applying the grout, eases the glass replacement works.
Sika has also improved the balustrade system. What if the architect wants to show the immaculate optical appearance of the whole glass and hide the floor slab? Sika has the answer: Sikasil SG-500 for structural glass bonding.
A perforated metal sheet, made of aluminium or steel, is bonded to the glass pane. The perforation in the metal profile allows the adhesive to through-cure whatever size bonding area is required. The glass pane may optionally have a screen print on the bonding area to hide the adhesive, as well as the metal profile. This innovative technology has also been tested by the Laboratory for Steel and Light Metal Construction and by Bucharest University for accident proofing, based on the technical regulations for the use of accidentproof glazing.
So, whatever design and construction the architect prefers, Sika has got the right product and technical solution - glass bonding is its passion.