Applications & Uses of Construction Adhesives

Decorative Interior and Exterior Bonding Applications

One of the largest application areas for adhesives and sealants in building/construction is decorative interior/exterior bonding. There are a myriad of applications construction adhesives are used, including:

Wall-to-wall Carpets
PVC Floor Coverings
Rubber Floor Coverings and Rubber Bonding
Parquets and Other Wood Floors
Ceramic Tiles, Stones and Similar Coverings
Wall Covering and Wallpapers Inside
Gypsum Boards
Roofing Adhesives and Tapes
Plastic Pipes Joint Cements
Interiors Panels
Solar Control Films

Bonding of Wall-to-wall Carpets

In Western Europe, wall-to wall-carpets are usually tufted carpets with foam or jute backing, and now more carpets namely "Action back" carpets where the backing is a grid made of polyester and polypropylene threads. In the past these carpets were bonded with solvent-based resin-alcohol glues, but now they are bonded with acrylic dispersion adhesives in Europe.

In Europe, carpets are bonded on the whole surface in order to prevent any "waving" of the carpet when heavy furniture are moved. The adhesives are applied with a notched trowel and the covering is usually 300 to 400 g/m², according to the roughness of the back of the carpet and the specific gravity of the adhesive.

In some countries, such as USA, Great Britain and other English speaking countries, the residential carpets are not bonded on the whole surface, but are stretched and then nailed on the periphery of the room onto "griprods" which are usually wood profiles with protruding nails, that are themselves screwed or glued on the concrete or wood floors. In these countries, the floors are often made of wood, and the construction techniques are different than in Western Europe where we use mostly concrete floors, and nailing onto the woodfloors is easy, which is not possible on concrete).

In commercial buildings of USA and UK, floors are made of concrete and thus the carpets are glued directly to the floors or sometimes installed over padding (e.g. in offices for extra comfort). In case of USA, the commercial carpets are bonded mostly with SBR latex and acrylic dispersion adhesives. The padding are bonded on the floor and the carpets are glued on the padding.

Bonding of PVC Floor Coverings

PVC floor coverings are used for commercial buildings, such as office buildings, shopping centers, hospitals and schools. In many cases they need to be cleaned by frequent washing with water and detergents and thus the adhesives must resist to water.

In Europe, USA and other countries, the main adhesives used for these PVC floor coverings are acrylic dispersions. They have a good resistance to water and to plasticizers migration from the PVC.

Some environmental organisms are against the use of PVC and therefore some countries have developed plastic floor covering made of polyolefins. These floor coverings are more difficult to bond, but acrylic dispersion adhesives that are properly formulated have given good enough results.

Rubber Floor Coverings and Rubber Bonding

Rubber floors may be bonded with 2k PU or epoxy adhesives at ambient temperature curing. Sometimes it may be necessary to clean the back of the rubber with a chlorinating agent in order to improve the adhesion.

Other rubber parts may also be bonded for instance on metal or concrete with properly formulated polyurethane adhesives or solvent-based polychloroprene adhesives (by the contact, double application technique).

Bonding Parquets and Other Wood Floors

The main market for parquets is now the laminated boards which are "loose laid". This means that the boards are laid without attaching it to the floor.

In the past, the boards were jointed together by a tenon-mortise assembly and a filet of water-resistant dispersion adhesive (e.g. special vinyl glue or VAE glue) was used to bond together 2 adjacent boards. But now laminated parquets are clipped or interlocked together by a special design of the edges which allows this interlocking, thus preventing the use of glues to bond the boards together. Laminated boards may be constituted of a 3 layers system:

The top layer is made of a high quality wood which provide the nice aspect
The medium layer is made of cheap plywood or MDF
The bottom layer is made of a cheap softwood.

Layers of Laminated Boards

These 3 layers are bonded together in the production plant, usually with melamine-formaldehyde resin cured at 80 to 100°C under pressure and sometimes using high frequency bonding.

In some cases, such as bonding on heating or cooling floors, the laminated parquets must be bonded on the floors (either concrete floors or wood floors), by using polyurethane, one or 2 components or MS Polymers adhesives.

Mosaic parquets and 15 mm thick parquet in small sections are still bonded on concrete or wood floors, mostly with vinyl adhesives but PU adhesives are more and more used for this application. MS polymers adhesives are also a good choice.

In USA, solvent-based SBR adhesives are the first choice for bonding parquets, and these adhesives are also used to bond wood based panels onto wood floor joists, by the technique called liquid nails which is a mix of nails and SBR mastics. But PU (one or 2 component) adhesives are more and more used for this, because they may be formulated as 100% solids products without solvents.

The mastic (in cartridges) is applied by hand gun on the joints as a bead of 6-8 mm diameter. Mastic Applied by Hand Gun

The mastic is also applied on the edges of the floor panels (particle boards, plywood or OSB) in order to bond it together and seal it against dust, water, insects. Mastic Applied by Hand Gun

Finally the floor is silent: it does not squeak when people walk on it.

Bonding Ceramic Tiles, Stones and Similar Coverings

There is now many different techniques and requirements for the installation of ceramic tiles on walls and floors, and similar mineral coverings such as natural stones, glass mosaic and thin wall decorative bricks. Tiles may be bonded on floors or walls, inside the buildings or outside, with or without waterproofing under the tiles in wet rooms or places (bathrooms, balconies) in order to prevent the water to pass through the joints and go down into the ceiling under the wet floor.

The adhesives and mortars may be rigid or more "flexible" when there is a risk of differential dilatation between the tiles and the substrates. The figure below shows a special case of bonding new tiles onto old ones with a 2K Polyurethane adhesive because the surface of old tiles is impervious and cement-based mortars would not stick to it. Therefore there is also many different types of mortars, additives, paste and ready-to-use adhesives.

Bonding New Tiles to Old Ceramic Tiles with a 2-component PU Adhesive

Let us only mention the different types of adhesives and mortars that every tile adhesive manufacturer should offer in its product range.

Normal thin bed mortars (rigid type, cement based with long open time, cheap formulation), wall type, floor type, used inside
Normal thin bed mortar, cement-based with long open time
High performances, high adhesion mortar for difficult-to-bond tiles and stones
Thick bed mortars for large tiles and uneven substrates
Special mortar for swimming pools and very wet rooms
Fast drying mortar
2K mortar with component A being a cement-based mortar and component B being a dispersion which provides improved performances, such as adhesion, flexibility

2K Epoxy mortar for very high resistance to water (swimming pools, chemical plants)
Water-based adhesive, normal grade, cheap version
Water-based adhesive with high resistance to water or longer open time
Epoxy or 2K PU adhesives for bonding ceramic tiles on impervious substrates (older tiles or metal)
Several types of joining compounds, sealants and waterproofing products
Sound deadening insulation systems, etc.

The most demanding application is the bonding of heavy tiles or stones on exterior walls & high rise buildings where the bonds must withstand the weight of the tiles, heat, rain, variations of temperatures and thus differential dilatation between tiles and the substrate, small movements of the building, etc. We can imagine that in the worst cases, it may become risky or dangerous to bond heavy tiles or stones on high rise buildings.

Standards for Ceramic Tiles

There is now some CEN standards for the installation of ceramic tiles, such as:

EN 12004 for the mortars and adhesives which defines many classes (C1, C1,T, C1E, C2E, C2T, C2G, D1E, D2E, D2TE, RG, etc.)
EN 13888 for joining compounds
French certification CSTbat 2001 for ceramic tiles adhesives

There are more standards to come in the next years.

In USA, there are several standards and codes of practice, such as:

The Handbook for ceramic tiles installation of the Tile council of America
ASTM C 658 and ANSI A 118.3 specifications for chemical resistant resin grouts, and others.

Bonding Wall Covering and Wallpapers Inside

This is a more simple operation. Several types of adhesives are used:

For wallpapers, the usual technique all over Europe is to use powder glues based either on cellulosic resins (methyl cellulose or carboxy methyl cellulose) or starch which are dissolved in water immediately prior to the utilization. The solids contents is very low (2 to 4%) according to the grades of polymers. The liquid adhesive is applied onto the back of the wallpaper which is left 10 minutes so that the water of the adhesive will swell the paper that will enlarge by some 1 to 2%, then the wallpaper is applied on the wall. After one night, the water dries and the wall paper will shrink back to its original dimensions, so that any wrinkle or bubble will disappear leaving a perfectly flat surface. But in USA, people are switching to ready-to-use dispersions based on vinyl or VAE dispersions.
For the vinyl or textile wall coverings, everybody in both countries uses ready-to-use vinyl, acrylic or EVA dispersions adhesives.

Bonding Wall Covering with a Vinyl Dispersion

Bonding Gypsum Boards

Gypsum boards are a huge market for interior walls, for instance the American and European market reaches ~300 millions m². In the past, gypsum boards were usually installed by screwing it onto wood studs, but now it may be bonded onto these wood studs or even directly on the concrete or concrete blocks walls.

This can be done with thick solvent-based adhesive mastics based on neoprene or SBR, which are applied from cartridges with a hand gun. Then the joining of panels together also needs a joining compound which may be either a ready mix paste (based on CMC or PVAc emulsion filled with some calcium carbonate) or a powder based on plaster modified with an additive which slows down the hardening of the plaster and some thickener to control the rheology of the mix with water.

Roofing Adhesives and Tapes

Recent roofing waterproofing systems include a vapor barrier, an insulation board such as PU foam and a polymer or rubber membrane which is bonded onto the insulation board, thus eliminating the need of a heavy ballast on the top which was usual in the past.

Mechanical fasteners or heat welding of the membrane rolls are also widely used instead of bonding. PVC and EPDM are the major membranes used in Europe and USA respectively. PVC membranes are bonded with polyurethane adhesives or nitrile adhesives, while EPDM membranes are bonded mostly with solvent-based neoprene adhesives.

Membranes may be bonded on the whole surface of the roof or only bonded at the seams. But, in order to resist to wind suction effect and to hold it on slopes or vertical surfaces, it must be bonded on the whole surface.

Butyl rubber tapes are used for the seams between 2 adjacent EPDM rolls, while the seams on PVC may be done by heat sealing or by bonding with PU or nitrile rubber adhesives.

Plastic Pipes Joint Cements

In Europe, water plastic pipes are made of PVC or CPVC the latter for heat resistance, in USA it may be PVC, CPVC or ABS. The rule for adhesive selection is simple.

PVC pipes are bonded with adhesives based on PVC dissolved in a strong solvent, usually a mixture of tetrahydrofuranne and ketones. As tetrahydrofuranne (THF) is a strong solvent, dissolves the PVC on the surface thus providing a solvent welding.
CPVC pipes are bonded with adhesives based on CPVC. It is also dissolved in a mixture of THF and ketones.
ABS pipes are bonded with adhesives based on ABS solutions.

Thanks to the THF, there is actually a solvent welding of the polymers, but the adhesive contains also 15 to 30% of PVC in order to fill the thin gap between the male and female parts. When the bond must resist to pressurized water (supply of water in the high stores buildings), the bond must be very reliable and needs a true solvent weld, which means that the adhesive must contain THF. There is a number of standards in Europe and in USA for the plastic pipes joint cements.

Interiors Panels

These panels and partitions are prefabricated in factories but some decorative panels are bonded on the walls, usually with polychloroprene or SBR solvent based mastics, sold in cartridges.

Beads of mastic, 5 to 8 mm in diameter are applied on the back of the panels, one line every 10 or 20 cm.

The panels are immediately pressed onto the wall (concrete or concrete blocks for instance), so that the adhesive transfers to the wall, then the panel is detached from the wall, laid on the floor for a few minutes in order to flash off the solvent so that the adhesive becomes very tacky.
Then the panel is pressed again on the wall at the same place, the 2 lines of mastic 'fuse' immediately together, providing a bond immediately, which is strong enough to hold the panel.

Adhesives are used to attach interior panels made of gypsum board, lauan or plywood to wood studs and framing. This technique is frequently used in USA and also in European Nordic countries where many individual houses are made of wood. Adhesives may be used along with nails in order to secure the bond when the builder do not rely on adhesives alone for a long term durability.

Thin plastic panels (3 mm thick) such as Polystyrene, ABS or FRP are sometimes attached to drywall in bathrooms and kitchens.

High pressure laminates, such as Formica, Polyrey and other brands may be bonded on site on MDF or particle boards with polychloroprene solvent based adhesives to make kitchen panels and shelves, in some developing countries where these kitchen furniture are not prefabricated but rather made on site, to the required dimensions and styles.

Bonding Thermal and Sound Insulation Panels

These panels may be PS, PU foam, other foams, glass fiber panels and mats, and it may be bonded with acrylic or SBR emulsion adhesives inside the buildings. Some insulation panels are composite panels made of glass fiber rigid panel bonded in the factory onto a gypsum board, such as CALIBEL from Saint Gobain and others.

Then on site, the whole panel is bonded onto concrete walls with a plaster-based mortar or putty.

Bonding Thermal Insulation on the Outside of the Walls

This technique called "exterior insulation" has been in use since it started in Germany in 70s.

Foam panels are bonded on the outside of the all, usually with a cement-based mortar. Then a polyester reinforcing grid is bonded on the foam and embedded into a decorative cement-based mortar or a decorative acrylic dispersion coating. Here the adhesive must resist to long term exposure to weathering, sun, rain & thermal cycles.

Some new systems including decorative bricks bonded onto foam insulation boards gives insulated and decorative panels which are then screwed onto the exterior wall. These systems are used in Netherlands and Belgium.

Solar Control Films

These are plastic films which are bonded on the exterior glass windows or glass panels in order to reduce the sunlight inside the rooms.

Reflective films include silver colored vacuum metallized films or tinted films. The reflective film is composed of:

A coating outside
A metallized polyester film
A laminating adhesive
Another clear polyester film with UV inhibitor
A pressure sensitive adhesive coat, and
A release liner

Usually solvent-based pressure-sensitive acrylic adhesives are used for both laminating and bonding to the glass. Solvent-based polyester adhesives are used for bonding together the 2 plastic films.

Structural Applications and Prefabricated Parts

The structural and outside parts must be properly designed for safety by the following means:

Whenever possible the high loads should be carried by both the structural adhesive and some mechanical help: adhesives bonds may be complemented by some mechanical fasteners if there is some risk of heavy parts falling from a high level
Use embedding, rabbeting and grooving in order to eliminate the cleavage and peel stresses and make sure that the bonds will work in shear rather than in cleavage, peel or tensile strength
Protect if possible the adhesive layer from excessive contacts with aggressive media such as water, chemicals & heat
Use adequate safety factors in the calculation of bonded joints and bonded surfaces.

A number of examples of bonded parts where the parts have withstood long term exposures in construction and civil engineering are discussed below.

Concrete for Segmental Bridges
Concrete Parts in Civil Engineering
Bonding Wood for Laminated Beams Arches
Glass for Architectural or Structural Glazing
Bonding of Metals
Exterior Decorative Panels

Bonding of Concrete for Segmental Bridges

Epoxy adhesives show a high adhesion to clean concrete, better than normal cement based mortars which require a perfectly clean and sometimes fresh concrete. They may be also formulated to provide a faster hardening than cement-based mortars.

The first segmental bridges have been bonded in Europe using epoxy adhesives. Here the concrete hollow blocks or segments (10 meters long) are bonded together and pre-stressed in order to form monolithic long span bridges.

Epoxies display excellent adhesion to concrete, even freshly cast, high mechanical resistance and proven long term durability. They have replaced cement-based mortars since many years.

The adhesive does not bear all the load because:

The segments have a special design where there is a keying which fits together the 2 adjacent concrete blocks so that there is a complementary mechanical fastening and joints are stressed with a mix of compression, shear and cleavage
The steel cables used for pre-stressing the concrete also contribute to a large extend to the overall mechanical strength of the bridge.

But the epoxy adhesive also bear a part of the total load.

In order to provide this keying, the precast concrete segments were "counter cast" for the first time on the Choisy bridge. Each concrete segment was cast directly against the previous one where the mating surface, with the proper keyed design was coated with a release agent, so that the second segment was molded onto the first one, thus giving an almost perfect match and therefore a fairly thin joint (1 to 2 mm thickness) which could be filled with an epoxy adhesive at an inexpensive cost.

Construction of Segmental Bridge

In these segmental bridges we may consider that the epoxy adhesive has several advantages and functions as compared to cement mortars. They are:

It bonds the surfaces so that compression, shear and in some cases also tensile stresses are transmitted between the segments.
It cures fast enough so that it allows a continuous erection of the segments.
It lubricates the surfaces of the joints to facilitate a proper positioning of the segments during erection
It provides a watertight seal of the joints so that the steel cables are protected against corrosion.

Concrete Parts in Civil Engineering

Pavement borders, steel or concrete poles, prefabricated concrete panels... are now more and more often bonded on concrete with epoxy adhesives instead of cement mortars. Epoxy adhesives are no longer considered as too expensive for these jobs because they may be heavily filled with sand, up to 500 parts of sand for 100 parts of epoxy resin, so that the selling price of the epoxy mortar is lowered down to some 2 euros/kg.

Reinforcement of concrete buildings and civil works

When concrete structures are damaged their mechanical resistance is lowered and it may become necessary to reinforce it. It is also necessary when the structures must bear higher loads than initially planned (for instance increased traffic and loads on a bridge).

Since 1970, many concrete structures have been reinforced by bonding steel plates (a few mm thick) onto the concrete, with 2 components ambient temperature curing epoxy adhesives, in order to increase mechanical resistance to deflection under loads.

This technique started in France with the procede UTI L' HERMITE. It was also used on a very large scale in the seventies in Switzerland and Japan. More than 500 bridges have been reinforced in Japan in order to bear the increase of heavy traffic since these bridges were built.

In England the reinforcement of several motorway bridges, floor beams of buildings, of car parks and many other examples, since 1975.

The figure below shows an example of a reinforcement of a concrete bridge by bonding steel plates, 3 mm thick, inside the hollow structure, which protects the bonds from corrosion and weathering , with an epoxy adhesive SIKADUR 31 from SIKA. The concrete and the steel plates were sand blasted, the steel plates were applied at a 30°C angle in order to bridge the existing cracks, and pressed against the adhesive and concrete by using props and struts.

Reinforcement of a Damaged Concrete Bridge by Bonding Steel Plates with Epoxy Adhesive

Many other similar site jobs have been realized by bonding either steel plates or, recently, carbon fibers fabrics impregnated and bonded to concrete with epoxy resins.

Bonding Wood for Laminated Beams Arches (or Glulam)

This technique was initiated in Europe by German and Nordic companies in the sixties. The idea was to manufacture very large structures, up to 40 m span, by bonding together wood lumber pieces or thick boards, 2 to 5 meter long, as shown below, formed in a straight or curved shape as required by the architects.

Laminated Beams Architectural Glulam

The best adhesives were found to be the thermosetting, 2 components resorcinol-formaldehyde glues (RF) because:

They give a very strong and stiff bond which will not "flow" under high loads and stresses.
They have an excellent long term resistance to aging, humidity, fire, and insects.
They have an acceptable price of ~3 euros/kg in large quantities.

Later, when prices of large lumber pieces increased, it became obvious that this technique would allow to use shorter pieces, and even recovered pieces which were not "square" so that their price was much lower, and computer controlled sawing, cutting and lay out allowed to assemble these various length and shapes in a proper way.

The RF glues are 2 components glues which cure at 60 to 70°C under pressure for 15 to 40 min. The main characteristics of ENOCOL RLF 185 a RF glue from ATO FINDLEY France specially designed for glulam bonding:

Mixing ratio: 100 parts by weight of ENOCOL resin for 20 parts of hardener
Pot life at 20°C: 2 hours
Required humidity in the wood: 10 to 16 %
Coating weight: 300 to 600 g/m²
Minimum press time: 1 hour at 40°C or 20 min at 60°C for bended beams increase press time 40%
Pressure 7 to 14 bars
Meets DIN standard 68705 for AW 100 bonds and BS 1203 and 1204 for WBP bonds
Tensile shear testing give rupture into the wood (at least 5 to 6 MPa)

Wood Reinforcements

Damaged timber may be repaired as shown below. The reinforcing bars may be steel rods or pultruded rods made of carbon -epoxy, and these rods are bonded with epoxy resin.

Repair to Timber Section

Wood-based Structural Panels

Floor or exterior wall panels may be manufactured by bonding wood or wood based panels onto wood joists or wood frames with high resistance phenolic glues. These glues are cured by heat and under 10 bars pressure in the factory. RF glues may also be used and cured at 40 to 50°C. Ambiant temperature curing adhesives (UF, RF, epoxies) may be also used on site, if necessary.

High Resistance Plywood

High resistance plywood may be used for factories floors are made of birch plies bonded with phenolic resins. They resist to boiling water, outside weathering and meet the WBP requirements and the following standards: EN 314 - 2 / class 3, DIN 68705 part 3 / type BFU 100, and also to the E1 standard related to formaldehyde gas release in the ambient air.

Bonding Glass for Architectural or Structural Glazing

Structural glazing is a method utilizing a silicone adhesive to attach strongly and durably glass to the structure of a building. The wind load and the weight of the glass panels are transferred through the silicone adhesive / sealant to the structure of the building.

This is a very demanding application because the whole system depends on the adhesion and the internal cohesion of the adhesive and its durability, and there is obviously a risk if the glass panel would fall from a high level.

However some mechanical fasteners (small metal clips which are almost invisible) are added in order to provide additional safety. This technique provides a beautiful aspect because the glass facade looks as a continuous wall almost seamless.

These systems must be carefully designed and calculated, the technical characteristics of the adhesives must be carefully assessed through various laboratory tests.
The glass must be bonded to its frame only in plants, under strict control (it can never be bonded on site because bonding conditions would not be constant and reliable).
The bond must be flexible in order to accommodate the different coefficient of dilatation (glass versus metal frames), the wind stresses and the movements of the structure.
The adhesive must have a long term durability, and the silicone manufacturers usually provide a minimum 10 years warranty, besides this, the bonds must be inspected on a regular basis in order to detect any defect before it becomes dangerous.

To ensure long-term durability for structural glazing, several European and other standards must be satisfied, such as:

Guidelines for European technical approval for structural glazing (ETAG 0022 part 1 september 1998)
CEN draft European standards CEN TC 129 / WG 16 - PrEN 13022, October 1997
Vitrages exterieurs colles faisant l'objet d'un avis technique, conditions generales de conception, fabrication et mise en oeuvre (Cahiers du CSTB 3130, mai 1999) in France
BSI: BS 6262 Code of practice for glazing for Buildings, Part 6, special applications (UK)
Standard guides for structural sealant glazing: ASTM C 1401-98 (USA)
GB 16776 – 1997: Structural silicone sealant for building (China)

The silicone adhesives/sealants which are used have only 1 to 2.5 MPa tensile resistance but this is enough provided that the joint total surface x tensile resistance exceeds by far the weight of the glass and the forces arising from wind effects and movements of the building.

Functions of the Silicone in Architectural Glazed Glass Panels

Insulated Glass (Double Glass Panels)

Figure below shows the general design of these insulated glass windows and the various adhesives and sealants which are used for the various materials, bonds and seals.

Several companies manufacture complete ranges of adhesives and sealants for the insulating double windows. For example: KOMMERLING (Germany), BOSTIK-FINDLEY (UK), TREMCO (USA and Europe), etc.

Double Glass Panels in Window Panes

Bonding Metals

Metals are seldom bonded in construction because it is more simple to assemble it with screws, bolts, rivets or welding and these techniques are well known for many years, unlike adhesive bonding. However, some applications in which light, thin, metal decorative panels or metal sheets could be bonded on various substrates or onto metal stiffeners. These applications have the following advantages:

No visible attachements thus providing a nice, smooth and perfectly flat surface for an improved aspect
No holes to be drilled and no corrosion or staining as would occur around metal fasteners
No deformation of the thin metal as it would occur if it was riveted or screwed or welded
Lighter construction: adhesive bonding allows the use of thinner metal sheets compared to welding, riveting, and the adhesive itself weighs less than bolts, screws or rivets.

Metal Facing Sheets

Studies have been made also to replace welding of hollow bars or tubes because welding on site may be difficult. These hollow sections may be used as bridge parapets or building elements.

The problem is that for bridges construction a design life of almost 100 years is required and no synthetic adhesive has such an experience of durability so far, but epoxies may be able to withstand such a service life, if we consider the durability curves which are available. A good start could be to try epoxies for repair jobs which are expected to last only 20 to 50 years.

Starting in 1952, exterior metal pipes for gas distribution in private housing have been bonded with 2 components epoxy heat curing adhesives, in France, and are still leak proof after 30 to 50 years, under a 5 bars pressure.

Sandwich panels made of metal honeycomb bonded onto metal sheet facings in a way similar to the aircraft panels should also be used in construction for special partition or to manufacture lighter elevator cabins for instance because of the weight.

Fixing and Anchoring Steel Rods and Bolts in Concrete

The figure below uses either chemical plugs containing the 2 components which are mixed after breaking a separation barrier between the 2 components or a 2 component cartridge which injects the mix into the hole. This technique utilizes polyester resin, epoxy resins or recently epoxy-acrylates.

Cement-based mortars are also used in a classical way in order to anchor bolts, rods, metal fastening parts into holes in concrete.

Anchoring of Steel Rods/Bolts into Concrete with Chemical Plugs

Bonding Exterior Decorative Panels

Several adhesives manufacturers have started bonding exterior decorative panels since 1995. The SIKA TACK Panel adhesive which is used for concealed mounting of ventilated façade panels such as TRESPA Meteon, Alucobond and Perstop Exterior. These panels are 4 to 7 mm thick and they weigh up to 10 kg/m².

Ventilator Panels (Source: SIKA)

SIKA TACK system includes first a double faced pressure sensitive tape which is used for immediate holding of the panels until final cure of the actual adhesive, and second the SIKA TACK adhesive, a 1 component moisture curing polyurethane adhesive. The main technical characteristics of this adhesive are:

Tack free time: 20 min at 25°C and 50% RH
Curing speed: 4 mm thickness per 24 hours same conditions as above
Service temperatures: -40 to + 90°C
Tensile strength: 4 MPa according to DIN 53504
Tensile shear strength: 2.5 MPa

It is assumed that the bonded area is large enough in order to be able to bear the weight of the panels, with a large safety factor. This is quite an interesting new technique which is already used on a large scale, and it is quite promising for many commercial buildings which are erected nowadays in developing countries such as China.

End-Uses of Construction Adhesives