Construction Adhesives and Sealants
Adhesives and sealants play a critical role in construction projects. They can add sustainability to existing structures and improve the longevity or service life of repaired dynamic or static joints.
They’re also easy to use and more convenient than nailing or screwing materials together. To help you choose the best adhesive for your project, look at the bonding characteristics and adhesive chemistry.
Versatility
A construction adhesive is designed to bond 2 elements together. There are many different types of adhesives for a wide range of applications, from bonding OSB and drywall to sealing windows and doors. The chemistry behind a particular adhesive or sealant will dictate what it can be used for.
For example, an epoxy adhesive is ideal for structural bonding but might not be suitable for a gap filling application. An acrylate or hybrid construction adhesive would be the better choice for the latter. The type of materials being bonded will also have an impact on which construction adhesive you use. For instance, a polyurethane adhesive will work well on non-porous surfaces like plastics and metals, but would not be suitable for a porous surface such as wood.
To get the most out of your adhesive it is important to follow manufacturers’ recommendations for surface preparation. For example, Titebond advises that substrates should be clean, dry and free of loose debris. For structural adhesives and sealants that will be used on metal, they may need to be cleaned by wire brushing or chemical etching.
Construction adhesives and sealants cure in different ways; by evaporation, by condensation, through a chemical reaction or by absorption. Heat can speed up evaporation and curing as well as induce a chemical reaction or condensation.
Fast Return to Service
The ability to quickly return a work area to use is important for homeowners and contractors construction adhesives and sealants alike. Neither party wants to be stuck waiting for an adhesive or sealant to dry and cure overnight. For contractors, minimizing wait time means more work completed per day and a larger profit margin.
Structural adhesives such as polyurethane and MS polymers require a certain amount of moisture to initiate their chemical curing process. Moisture usually exists in the materials to be bonded, but can also exist in the air. Therefore, the substrates must be properly prepared to minimize the amount of moisture that comes in contact with the adhesive or sealant. This may involve a surface treatment or primer specified by the adhesive or sealant manufacturer. It may be necessary to test humidity levels with a humidity tester or refrain from bonding when the ambient air is over a specific value.
Non-structural construction adhesives bond decorative or non-durable materials that don’t need high strength (wood trim, interior doors and some fiberglass doors). They are usually emulsion or dispersion, neoprene contact, solvent-based, epoxies and polyurethane adhesives.
Caulks and sealants bridge gaps between surfaces to look neat and tidy, typically at a lower cost than adhesives. They have lower-strength bonds and are more flexible. There are many options for caulks and sealants, including emulsion and silicone-based ones, neoprene contact and solvent-based, as well as natural or renewable materials.
Hybrids
Choosing the right adhesive for any application requires trade-offs. But the hybrids available in the market today are reducing those trade-offs by offering high-performance options that work well across multiple applications without sacrificing grab strength, ease of use or service temperature ranges.
A hybrid construction adhesive is an advanced formulation that uses a blend of components to create the best possible performance for its intended application. These adhesives may include vinyl acetate or acrylic emulsions, neoprene contact or polyurethane construction adhesives. These hybrids often provide higher levels of tensile shear or peel strength and improved durability than their individual component parts alone.
Hybrid adhesives usually require a small amount of moisture to begin curing. Moisture can be provided by spraying the surface or using a misting bottle when bonding nonporous surfaces. The moisture will initiate a chemical construction adhesives and sealants reaction that produces the necessary adhesive strength. These types of hybrids display good adhesion to metals, plastics and composites.
A second type of hybrid construction adhesives includes those formulated from silane polymer prepolymers. These materials are end capped with methyl dimethoxy silane to allow them to cure by the presence of moisture. Some are one-part systems with accelerator or a catalyst, while others are ambient curing systems that harden over time in an environment of humidity and temperature control. These materials typically display excellent adhesion to concrete, ceramic tiles and bricks and have a tensile shear resistance up to 20 MPa.
Storage
In order for construction adhesives to work, they must be kept dry and in a cool place. They may need to be stored in buckets, gallons, bottles, tubes or cartridges. These products are stocked at hardware stores, lumberyards and home-improvement centers. Adhesives are used by tilers, carpet applicators, wood workers, contractors and builders daily to bond materials together instead of nails or screws.
Unlike sealants, which are intended to fill gaps and cracks, construction adhesives form strong bonds between surfaces. They are used to connect drywall, wood, glass, metals and other construction materials, including insulation foams. Adhesive bonding also requires that the surfaces being bonded be clean, dry and fairly flat (unless the adhesive tolerates thick joints). Structural and non-structural materials must be properly prepared for adhesion by wire brushing or solvent wiping, or chemically etched.
Most adhesives take hours to set and cure, but there are some that are formulated for instant grab. These are great for projects that require a quick bonding, such as installing an aluminium sign panel. For the best results, always follow the manufacturer’s instructions for use and storage. Adhesives and sealants should be stored in a dry area, away from heat sources and not exposed to direct sunlight or wind. It is important to keep a first aid kit and emergency contact information close at hand when working with these products.
