For any construction or renovation project, there are many things to consider. From the technical drawings to the types of materials and labor costs, these are all the important elements that can make or break your project. One such aspect is the types of sealing you use, which while they may seem like a minor consideration, are vitally important. Sealants are used to fill cracks, waterproof openings, and protect construction joints from harmful outside factors.
To help you get a better understanding of how they are used and which ones are available, here is a guide to common sealing solutions for construction projects.
1. Traditional Caulks or Putties
Traditionally, construction joints between different types of materials were sealed with traditional caulks that had decent elongation and could withstand light weather conditions.
- Oleoresins such as linseed oils or blown soy are filled with mineral fillers and plasticizers. As oleoresins oxidize, they harden up and become brittle – but lack flexibility and movements. The maximum amount of elongation that they can reach is about 5%, which is not enough for prefabrication techniques.
- Bitumen and tar are used more in civil engineering applications, where filling large gaps with high-performance polymers is too expensive. More improved formulations have rubbers, styrenic polymers, or polyurethanes in them – which pushes the elongation limit up to 10-15% and the movement capabilities up to 20 - 25%.
As prefabricated construction parts and new synthetic polymers have been developed, caulks and putties are rarely used today.
2. Sealants Based on Synthetic Polymers and Rubbers
Synthetic polymers and rubbers add new elements of elasticity and durability to the standard sealant. You can learn more about these new sealants from this industrial rubber company here, which explains the benefits of polymers and rubbers. And the gist of it is that through adequate formulation, they can be customized to fit any specific requirements.
Here are some examples of these polymer classes:
- Polybutene is blended with fillers, fatty acids, and solvents, and then dried. It can also be mixed with butyl rubber for making plasticizers. As non-curing sealants, they are widely used in joint-filling applications where elasticity is not that important.
- Polyisobutylene (PIB) is used to modify other types of sealants made from oleoresinous or butyl rubber.
- Butyl rubber sealants are impermeable to gases, can withstand decent weather punishments – with average elasticity (up to 40% in terms of elongation rate and are used for joints with up to 15% movement rate). They are also 100% solid with no shrinkage.
- Butyl and polyisobutylene hot melt sealants are suitable for double window sealing against humidity.
3. Acrylic Sealants
Acrylic sealants are very useful in a range of applications. Common additives used in acrylic sealants include fillers, plasticizers, dispersing aids, and silanes.
Here are 2 different types of acrylic sealants:
- Acrylic emulsion sealants offer pretty good adhesion to many different types of materials. They allow movements up to 10-15% and shrink about 10-20% during their lifespan (about 15 years). Being sensitive to water, they provide good weather and UV resistance. Discoloration does not happen with acrylic emulsion sealants, which is why they are formulated to match the colors of the materials.
- Acrylic solvent sealants present excellent adhesion to a wide range of materials and have impressive weather, UV, and staining resistance. They allow movements up to 10% and shrink about 15% during drying. Modern formulas that contain elastomeric acrylic polymers and plasticizers help ensure that the shrinkage will not have any significant impact on the interface between the sealants and the materials.
4. Elastomeric Sealants
Elastomeric sealants are considered high-performance sealants that allow high capabilities of movement and elongation rate (about 15-40%). Here are 4 different types of elastomeric sealants:
- Polysulfide sealants are the first generation of elastomeric sealants with incredible overall resistance, but they are not very elastic and are very expensive in price. And although their applications in both construction and civil engineering are numerous, they are a step behind other options like silicones or polyurethanes.
- Silicone sealants are factory-made with either one or 2-component silicones. They are the most famous sealants at the moment because they offer great resistance to all types of harmful factors and superior specifications when compared to others. These 2 elements combine for the outstanding lifespan of at least 40 years, and the fact that they are manufactured in large quantities means that you can get them at affordable prices.
- Polyurethane sealants are either single or 2-component sealants that can be used to obtain various types of products and properties. Depending on the formula, the features might change – but in general, you can expect a good elongation rate (12-25%), remarkable elastic recovery (at least 90%), great adhesion, and a long lifespan (about 20 years). However, they cure very slowly and do not have great resistance against chemicals, UVs, or oils. They are commonly used to fill floor joints.
- MS Polymer sealants are new on the market but offer many promising features: 25% elongation rate, at least 70% elastic recovery, and great adhesion on a wide range of materials. They can withstand tough weather conditions and last for about 15 years but are prone to degradation when prolongedly exposed to UV rays.
5. Impregnated Foam Sealants
Impregnated foam sealants are essentially polyurethane polyester foam strips that have had different tacky sealing compounds added such as butyl and PIB. This makes for sealing tapes that require compression between the parts to be sealed. Their applications include prefabricated concrete panels, curtain walls, wood panels, and window installations (wood, aluminum, or PVC).
6. Backup Materials
Backup materials (polyurethane, polyethylene, neoprene) are round or rectangular foam strips that are inserted at the base of the joints and set the foundation for the sealants’ application. This technique will give you control of the sealants’ depth, as well as providing support for sealants that are applied in horizontal joints.
As a rule of thumb, the sealants and the backup materials are separated so that the solvents from the sealants will not have any impact on the backup materials. Based on the type of sealants used and the job site conditions, you will need to choose between open or closed-cell materials.
When applied properly, these sealing solutions will protect your construction structures against surface tension and air pressure fluctuations. They will also prevent long-term issues like an infestation, leakage, and weather damage. In order to choose the appropriate sealing solutions for your construction project, consider different factors like strength, flexibility, appearance permanence, solubility, and corrosion resistance.