In building construction, the ever-increasing need to balance structural integrity with durability demands stronger, lighter and more resistant substitutes for traditional materials. Composite materials created from high performance thermoset resins, corrosion-resistant resins or structural adhesives help deliver superior end products. In addition, the non-toxic, biodegradable resins now promise high efficiency yet greener construction materials.
Resins are a basic yet an important constituent of many architectural products. They are both naturally occurring & synthetic and are often used in manufacturing protective coatings, decorative paints, concrete binders, sealants and reinforced glass for various uses in buildings.
Natural resins are commonly produced by fir and pine trees. These highly adhesive, viscous liquids can be grouped into oil-soluble and spirit-soluble types. Natural resins like Copa, Dammar, Mastic and Venice turpentine have a wide variety of uses in building industry ranging from sealants to cover the cracks in timber, in varnishes, paints or lacquers to create a hard, smooth, impermeable surface and as solvents such as turpentine for architectural purposes.
Synthetic resins belong to a large group of chemical components that also include plastic, rubber and fibre. Some of the commonly used synthetic resins include vinyl toluene, urethanes and polystyrene, silicon and epoxy resins. Various forms of synthetic resin are used in building applications and products such as plastics, paints, coatings and flooring. Ritesh Bhutani, Principal Consultant-Phoenix Engineering Solutions elaborates, “Synthetic resins are manufactured using chemical polymerization process and have properties similar to the naturally occurring resins but are more stable, durable and high performance. Polymer based water soluble resins are used in buialding industry as thickeners, binders and association compounds in paints, coatings, paint removers, cements, and concrete. The widest application resins find is in the production of composite materials like Fibre-reinforced Plastics (FRPs), glass-reinforced plastic (GRP), sandwich composites and engineered wood.”
Paints & Coatings
Alkyd resins, natural or synthetic are the most common resins for oil based paints, varnishes and enamels and make excellent wood primers. They add superior surface penetration and adhesion properties to the paint which can be applied on variety of substrates.Vinyl Toluene is used in water based paints for enhanced coverage.The paint does not require two or three coat application, is flexible and provides long lasting paint surface. Alternatively, acrylic resin paints are good finish coatings for wood and concrete as they are highly vapour permeable. This paint is mostly used for exterior application as it is resistant to fading and chalking.
Epoxy coatings are also used on wood, plastic, granite, marble, and fiberglass and provide good corrosion protection for steel and interior concrete floors. They form a hard and durable finish with high surface adhesion and resistance to moisture and alkali. Moreover, as coating is waterproof, it is also used for swimming pools and underwater projects. Likewise, Urethanes and polyurethanes are suitable for protection of surfaces such as gymnasium floorings, for water proofing concrete decks and as sealers and finishes for wood. According to Navin Mehra, Sales Director, Kamson Chemicals India Pvt Ltd, “Water-based Polyurethane dispersions (PUDs) have low volatile organic content, high abrasion resistance, and low temperature flexibility. They also have excellent UV resistance, offer enhanced penetration into the substrate and can be used as coatings for glass, clear glossy finishes for wood and veneers and anti-corrosive coatings for metals.”
The latest silicone based paints and coatings are highly elastic, vapour permeable, UV resistant and waterproof and need few application coats. Also, silicones have the ability to crosslink with silica present in sand and concrete which enhances durability and because of their low surface energy can spread on the substrate to better demonstrate their hydrophobic nature. Padmadas Nair, Commercial Manager, Dow Corning Construction Solutions says, “Silicone-based high performance coatings provide an edge in building construction, since silicones resist corrosion, electrical discharge, moisture, and extreme temperatures. In addition, they are highly resistant to weathering and the sun’s UV rays. These coatings are compatible with many organic resins and can be applied to almost any material or surface. Moreover, water-based, solid flake and 100% silicone liquid silicones enable formulators to reduce the volatile organic content (VOC) of their formulations, thus helping in compliance with green building norms.”
Sealers & Adhesives
As resin adhesives can be used on almost any type of material including metal, glass, plastic, ceramics, and stone, they are extensively used in the construction industry to join varied building materials. Once applied, it forms a very tight and strong bond. It is resistant to temperature or humidity changes, high levels of heat as well as a wide variety of chemicals. They are also extremely moisture-resistant and can be used in all types of underwater applications.
Although, common synthetic resin sealants are fairly weather resistant and prevent mold and mildew growth, they cannot block sunlight damage. Therefore, an epoxy fortified synthetic resin is considered more appropriate for wood. The epoxy sealers have the ability to deflect and absorb the ultraviolet light that can be damaging to wooden surface. It seeps deep into the wood, making the planks water-repellent not only on the surface, but also from within. Also, the high surface penetration of epoxy sealers keeps it from peeling.
For concrete surfaces, silicone, acrylic, and polymer resins are some of the prevalent sealers. Polymer resin sealers comprise urethane and poly urethane concrete sealers that provide high chemical and abrasion resistance combined with smooth appearance. They can bed layered, brushed, sprayed or caulked over surface and are suitable for industrial concrete floors, concrete counter tops as well as decorative concrete walkway. Siliconate concrete sealers, in contrast, forms a permanent chemical change in the concrete resulting in surface protection and reduction in moisture and freeze thaw damage and stains. They significantly reduce porosity in concrete, stucco and other cementitious surfaces and usually used for sidewalks, driveways and poured basement walls. Dow Corning offer silanes in emulsion and powder form for integral water-proofing of cement mortar and has introduced elastomeric coatings for walls that create water-proofing membranes and impart crack-bridging ability.
Alternatively, waterborne acrylic sealers form a transparent film over the surface of the concrete and offer a low cost decorative appearance for concrete pavers, stamped concrete or pool decks. For example, Parex Group, France, acrylic based multipurpose primer increases the bond strength of cementitious mortar systems, such as floor levellers and repair products. It can be applied over timber, concrete and common porous building substrates. As per, Tim Holfert, Executive Vice President Parex Group & MD Asia Pacific, “The demand for high performance products is being fuelled by need for refinement of existing products. High strength technical mortars, primers and bonding agents find applications in specialized areas of building construction such as concrete maintenance and protection solutions.”