What is adhesives?
Any substance that can bind or hold two materials together and prevent their separation is referred to as an adhesive. Adhesives are commonly referred to as cement, mucilage, glue, or paste. These words are classified as organic materials. Because they can keep bricks and beams together, inorganic compounds such as Portland cement can also be called adhesives. Adhesives have advantages over traditional binding methods such as sewing, mechanical fastening, or welding. These advantages include the ability to bind several materials together, more effective stress absorption across a joint, the utility of an easily mechanized process, and more design freedom.
Adhesive can be derived from natural sources or synthesized. Natural adhesive have been used since ancient times, approximately 200,000 years ago. 3,300 years ago, Egyptians were gluing pieces of veneer together. The Papyrus fabric was bonded together with flour paste. Animal and fish glues were at their peak during the 18th century, and in the 19th century, rubber and nitrocellulose-based cement were used. The Greeks and Romans made significant contributions to the advancement of adhesive. The desire for adhesive with high structural strength and resistance to fatigue and harsh climatic conditions contributed to the growth of strong materials, which finally found their way into a wide range of industrial and consumer applications.
Kind of Adhesives
Adhesives are frequently made from polymers or resins. They are made of various materials.
- Pressure-sensitive adhesives are mostly composed of acrylics, rubber latex, and silicone. They do not require the use of a solvent, water, or heat to attach and may be applied with little pressure. Take, for example, cello tape.
- Polymer adhesives include polyester, polyurethane, acrylate, and epoxy. They are useful for wood binding, food packaging, and automated manufacturing.
- We utilize cyanoacrylate adhesive polyvinyl, which is a type of super glue.
- We often utilize polyvinyl acetate, or PVA, as an adhesive in school or college to bind papers together.
- Because they are used to bond cell phones and computer equipment, reactive adhesives are essential.
- Solvent-based adhesives: A solvent is a liquid that dissolves other components to generate a solution. This type of glue is polymer-based and may be found on sticky notes.
Types of Adhesives Uses in Construction
There are several types of adhesives available on the market and utilized in buildings. It is dependent on the application and conditions. Adhesives can be found in nature or manufactured synthetically. The following are some of the adhesives often used in building construction.
Natural adhesive are primarily made from animals or vegetables. They are also known as “bio adhesives”. One of the simplest examples of natural adhesives is the paste, which we make from cooking flour by mixing it with water. That is used for sticking paper and other things. Animal glues have long been employed in bookbinding, wood joining, and a variety of other applications. Natural adhesive are not that strong. They are used to stick wood, paper goods, and light small materials together, like corrugated boards, envelopes, bottle labels, book bindings, cartons, furniture, and laminated film and foil.
It is made by dissolving casein, water, and an aqueous alkaline solvent together. Casein is a protein that is found in milk (of any animal). It is used for wood bonding and has good moisture resistance and aging characteristics. Casein can also be used to improve the adhesion of paints and coatings.
Animal glue is a strong liquid adhesive that is prepared from mammalian collagen, the main protein component of skin, bone, tendons, muscles, and other tissues. The typically insoluble collagen progressively becomes soluble when handled with acids, alkalies, or hot water. Gelatin and lower molecular weight residues of collagen, keratin, and elastin make up the majority of animal glue. Animals from which this glue is prepared are horses, rabbits, and fish (can be others).
Animal glue is used for wood joining, book bindery, sandpaper manufacture, heavily gummed tapes, and others.
Water Based Adhesives
Water-based (or waterborne) adhesives are often made from natural polymers and synthetic soluble polymers. Because it contains no volatile organic molecules, it is an excellent alternative to solvent-based systems (VOC). It is lighter in weight, poses no significant health risks, and emits no harmful or odorous gases. Because they are frequently wet-bonded, at least one of the substrates must be permeable to allow water to escape from the bond line. As a result, these adhesives are frequently used to join wood, paper, textiles, leather, and other porous substrates.
Anaerobic adhesives are also referred to as thread lockers or retaining compounds. They are used to cure metal surfaces in the absence of oxygen. They are less hazardous than other acrylics, have a moderate, unobtrusive odor, and are not metal-corrosive. Anaerobic adhesives are kept in partially filled polyethylene containers with a high air-exposed surface-to-volume ratio.
They are used for structural bonds, generally with materials like metal and glass. Because of the lack of oxygen requirement, it doesn’t bond well with plastic and rubber.
Acrylics are not glued together; they are chemically welded by a special process that melts the surface of the plastic and fuses them permanently. Used for acrylic and some types of plastics. Because of its good strength and cheap price, it is naturally in very good demand.
Structural adhesives are adhesives that have a high weight-bearing capacity, a long lifespan, and are resistant to heat, solvents, and fatigue. They are available in paste, liquids, and films.
The adhesives listed ahead are well-known structural adhesives: Epoxies, Polyurethanes, Acrylics, Anaerobic, Cyanoacrylates, and Silicones
Epoxy adhesive is a type of structural adhesive that has the best strength and overall good performance. They come in single-component systems for heating and two-component systems for curing at room temperature. Used for the bonding of materials like metals, ceramics, wood, and plastics.
Resin adhesive has a super bonding capacity. It is manufactured in spray, emulsion, liquid, and powdered form. It is not water resistant and can affect the durability of the material if applied. Resin Adhesives are used for bonding various materials like wood, fabric, glass, or metal.
Plastisol adhesives are single-component compounds that are applied to the substrate as a paste. The paste is made up of solid polyvinyl chloride (PVC) particles that have been distributed in a plasticizer. It has high flexibility and better peeling resistance. They provide good adhesion to metals (oiled) and plastics. We can apply them easily on the surface, and they don’t require metre mixing, so they have fast processing.
There are several others, The list gets long and long.
Pressure-sensitive adhesives, Hot – melt adhesives, Ultraviolet cured adhesives, Polymer Adhesives, Electric cured adhesives, Pressure adhesives, thermoset adhesives, and others.
Uses of Adhesives in construction
Adhesives are bonding agents and are good for gluing materials together.
- Floor and Wall Covering
- Transporting Industries
- Carpet Laying
- Countertop Lamination
- Drywall Lamination
- Anchoring System
- Heating, ventilation, air conditioning connections, and others.
- Wooden construction
- Pre-fabricated panels
- Building Facades
- Resilient flooring
- Labeling and Packaging Industry
- Corrugated Board
Advantages and Disadvantages
Advantages of adhesives in construction
- Provide a more uniform stress distribution.
- Enable the construction of lighter structures.
- Adhesives can help with controlling vibration, damping, sealing, and noise insulation.
- Deliver more flexibility in terms of design and manufacturing processes.
- Allow joining of a wide range of materials, including dissimilar materials.
- Provide good vibration damping properties.
- Allow for combined joining and sealing properties in one bonding.
- Avoid damaging the fibers in composites with through-holes.
- Ensure no direct contact between the parts to be bonded, avoiding corrosion.
- Provide either electrical/thermal conduction or insulation.
Disadvantages of adhesives in construction
- The requirement for a careful and suitable selection of surface treatment
- Incorrect surface preparation can have a drastic effect on joint strength
- Limitation of thermal loads
- Weathering and/or other influences cause aging.
- Low peel and cleavage strength.
- Limitations with the handling time during manufacturing.
- Special fixture requirements that allow holding together the joined parts during the curing process
- Difficult disassembly of the bonded parts, which creates challenges both for the repair and the recyclability of bonded parts.
- Low resistance under extreme environmental conditions
- Wide variation of mechanical properties as a function of environmental conditions exposure.