What Is Sealant?
The term “Sealant” can be simplified as “sealing elements”. Sealants are the materials, which are used to seal the progress of substance between two surfaces, or where two different characters meet.
In the civil engineering field, sealants are materials, which is used to block the passage of any fluid or fluid-like substances, which are progressing through the surfaces, or joints, or opening in materials, a type of mechanical seal. The materials used for the manufacturing of sealants are the often chemical compounds, both organic or inorganic.
In building construction, the first stage is earth excavation, which is then followed by dewatering the trenches, laying of brick flat sloping and PCC layer, placing of reinforcement caging for the construction of footings, and finally the Concreting of foundations.
After the footings have been constructed, the construction of the column is done in the same manner, following placing of reinforcement cages for columns, shuttering, and finally Concreting.
After all the columns of the building had been concreted up to the first-floor level, the construction of beam & slab begins. As most of the building nowadays adopts monolithic casting of floor beams and furniture due to the better loading resistance, the reinforcement caging for slabs and beams are placed, which is then followed by Concreting of floor beams and slab, simultaneously.
After the Concreting work is almost finished, the brick walls (in a framed structure, they are used as partition walls) are constructed, which is then followed by building finishes and additional works, such as plumbing, electrification etc. In the construction of the building, many types of joints are observed (a joint is where two walls meet, two floors meet, or one wall and one floor meets, in a building).
Due to many reasons, in inadequate dewatering, faults in plumbing system etc., Accumulation of fluid may occur in those joints, resulting in increasing dampness of the building in the floors and the roof.
Due to this dampness, water patches will be observed on the building surfaces, and ultimately cracks appear. This propagation and leakage of water can be stopped by using specific adhesive chemicals compound, which is known as sealants.
In early times, mud, grass and seeds were used as waterproofing elements for building construction. Adhesive resins such as bitumen, tar, natural gum, wax etc. have been widely used for this purpose. In the 17th Century, the first putty was applied to window joints to prevent the movement of the fluids.
Later, drying oils have been used for the manufacture of oil-based putty, which also acts as an efficient sealant. In modern times, polymers, such as acrylic polymers, butyl polymers are widely adopted, because of it’s numerous applications. Polysulphide sealants, silicone-based sealants, polyutherene sealants, are popular choices of sealants.
Functions of a Sealants
A sealant is a substance used to block the passage of fluids through the surface or joints or openings in materials, a type of mechanical seal. In building construction sealant is sometimes synonymous with caulking and also serve the purposes of blocking dust, sound and heat transmission.
There are many functions of a joint sealant, some of which, have been mentioned below
- The primary function of a sealant is to seal the joints or to seal the top of a structured surface with the substrate situated under; thus it is used as a waterproofing material, it prevents spreading water by forming a membrane system.
- The sealants provide excellent thermal and acoustic insulation; thus, it is also a perfect choice as a fireproof material.
- They may have electrical characteristics as well, therefore used for simple shooting or filling.
- A joint sealant maintains its sealing property for its estimated lifetime.
- It is an economical approach to waterproofing purposes as the sealants do not cost much, can be found at any stores, can be applied quickly and effectively, and can last longer conserving its sealing properties.
- They are also being used in extreme weatherproof materials.
- In places where the amount of rainfall is very high, there are high chances that dampness will occur at the building due to the accumulation of rainwater.
- In such places, joint sealants are used as an integrated part of building construction, to waterproof the whole building.
What Is Polysulphide Sealant?
Polysulphide sealants are the resins that basically provide a very flexible and also resistance that is chemically adhesive. The component ‘Polysulphide‘ resins were very commonly used in the form of construction sealants. Polysulphide sealants have a huge resistance to saltwater, ozone, sunlight, and files.
How to Make Polysulphide Adhesive?
Polysulphides are chemical compounds, consisting of chains of sulphur atoms. In chemistry, the term “polysulphide” refers to a class of polymers with hydrocarbons and several sulphur atoms. Polysulphides are a group of polymers, which can be synthesized by condensation polymerization.
Polysulphides ate invaluable in water, like and several other organic substances and fluids. Due to its insolubility in water, it can be widely used as a sealant for joint or fill sealing purposes such as in pavement, automotive window glasses, aircraft structures, as well different marine structures, and residential buildings.
Polysulphide Joint Sealant
Pour Grade is a two-component Polysulphide sealant. It is used for sealing expansion joints where large movement is anticipated in concrete construction and for joints between diverse construction materials. As already mentioned earlier, polysulphide sealants are generally manufactured from Polysulphides. Often a tome epoxy can be used for preparing polysulphide sealants also.
Polysulphides and epoxy are two adhesive resins which provide higher toughness to sticky action and have increased flexibility as compared to pure epoxy.
Polysulphide resins are commonly used for sealing the construction joints and are known as construction sealants. This compound shows high resistance against various weathering factors such as sunlight, saltwater, ozone, fuels, and ultraviolet rays.
Use of Polysulphide Joint Sealant
- The main uses of polysulphide sealants are to seal off different kinds of channels (as most of the time, the water accumulates and propagates through the tracks) and joints in construction processes.
It generates a strong seal within both the surfaces, thus minimizing the water leakage risk in several areas, damage or erosion.
- Polysulphide sealants can also be used for sealing in channels, in water reservoirs, culverts, dams, canals, and even little works like flood control waterways.
As polysulphide sealants are insoluble in water, their solving resistance makes this material perfectly suitable for the construction of marine structures.
- Polysulphide sealants are wife used in automotive and aerospace industries for the sealing of fuel tanks and fuselages in aircraft.
Since this type of sealant has a strong resistance to fuels and other types of chemicals, they provide a particular kind of lasting seal in components of the aviation industry.
Advantages of Polysulphide Joint Sealant
- The main advantages polysulphides sealants are that it provides an effective adhesive action and high flexibility. Pavements (airfield pavements also), there are greater chances of expansion and contraction due to temperature fluctuations and weathering effects.
So in such a case, the sealants provided between the joints must have high flexibility to accommodate itself with consequent expansion and contraction, taking place into pavements. In the absence of that property, the purpose of the sealants is diminished.
- Due to its adhesion property, it is often incorporated initially in the construction procedures waterproofing material. In places where there is excessive rainfall, there are high chances of dampness in buildings, which can be resisted by installing polysulphide sealants In the construction phase.
What Is Polyurethane Sealant?
- PU Sealant is a one-part, elastomer sealant based on urethane which cures at room temperature.
- It is mainly used in applications relating to assembling and sealing.
- For these applications, the product is referred to as adhesive sealant or polyurethane adhesive sealant.
How to Make Polyurethane Joint Sealant?
Polyutherene sealants are manufactured from the chemical compounds polyurethane. This polyurethane are used to manufacture high resilience foam coating, rigid foam insulation panels, gaskets, spray foam, etc. Polyutherene consists of two types of monomers, which generally polymerase, one after another, so they are typically classed as copolymers.
Polyutherene is an organic material. Polyutherene joint sealant has high flexibility, adhesion strength, hardness, and can be manipulated according to its needs for use.
It’s mechanical strength, and tensile strength can be very high as compared to silicone. Polyutherene construction sealants have high ultraviolet resistance, this it is the most common type of sealants used for the construction of reactors and radiation shields.
What Is Polyurethane Sealant Used for?
Polyutherene sealants are primarily applied for domestic waterproofing purposes. Most of the waterproofing sheet membrane system which is being used for the rooftop waterproofing, are manufactured from polyutherene.
It also provided good thermal insulation and chemical adhesion, which is why it is also used for fireproofing purposes. Polyutherene sealants are used in joins of prefabricated building elements, in joints of rainwater collection pipes in the roofs, and for rain gutters. They are also used for insulating the joints between precast concrete blocks, having excellent thermal insulating material.
Advantages of Polyurethane Joint Sealant
- Polyutherene sealant has high adhesion on any building materials, as it can be applied on surfaces of structural members.
- Polyutherene can primarily be used for both exteriors as well as interior works. As the material is not exposed to high temperatures, it can sufficiently withstand large swings.
- Whenever a polystyrene coating is applied, unlike any other joint sealants, it provides colouring of the polyutherene layer.
- The composition is chemically resistant, as it does not react with any chemical compounds, does not rust, and are resistant to precipitation.
Difference Between Polysulfide Sealant and Polyurethane Sealant
| Sr.No. | Polyurethane Sealant | Polysulfide Sealant |
| 1 | Polyurethane is the best sealant for the hull-to-deck joint. | Polysulfide sealants are designed for joints that need to withstand prolonged immersion in liquids |
| 2 | It is used in joints between prefabricated building elements, in joints of rainwater collection pipes on roofs and in rain gutters, insulating joints between precast concrete blocks and sealing of joints of aluminium pipes in HVAC (ventilation) sector. | It provides a seal which is totally waterproof and due to it, it minimizes the water leakage risk in the area, any kind of damage and erosion. |
| 3 | Polyurethane sealant is excellent bonding can be used without primer | Polysulfide sealant exhibits excellent chemical resistance |
| 4 | Polyurethane sealant is Good UV resistance | Polysulfide sealant is a good performance in submerged conditions. |
FAQ: Sealants in Construction
What is a sealant?
A sealant is a material used to block the passage of fluids through surfaces, joints, or openings in materials. It acts as a mechanical seal, preventing substances from passing through the areas where two surfaces meet.
What are the main types of sealants used in construction?
The main types of sealants used in construction include polysulfide sealants and polyurethane sealants. Each type has its specific properties and applications.
What are polysulfide sealants?
Polysulfide sealants are resins that provide flexibility and chemical resistance. They are commonly used in construction due to their resistance to saltwater, ozone, sunlight, and fuels.
How are polysulfide sealants used?
Polysulfide sealants are used to seal expansion joints, channels, water reservoirs, culverts, dams, canals, marine structures, and in the automotive and aerospace industries for sealing fuel tanks and fuselages.
What are the advantages of polysulfide sealants?
Polysulfide sealants offer high flexibility, excellent adhesive properties, and strong resistance to various weathering factors such as sunlight, saltwater, and fuels. They are also durable and provide effective waterproofing.
What is polyurethane sealant?
Polyurethane sealant is a one-part, elastomer sealant based on urethane. It is used for assembling and sealing applications and is known for its high flexibility, adhesion strength, and ultraviolet resistance.
How is polyurethane sealant used?
Polyurethane sealant is primarily used for domestic waterproofing, thermal insulation, and fireproofing. It is applied in joints of prefabricated building elements, rainwater collection pipes, rain gutters, and insulating joints between precast concrete blocks.
What are the advantages of polyurethane sealants?
Polyurethane sealants have high adhesion to various building materials, can be used for both interior and exterior applications, and provide excellent thermal insulation and chemical resistance.
What is the difference between polysulfide sealant and polyurethane sealant?
- Polyurethane Sealant: Best for hull-to-deck joints, used in prefabricated building elements, provides excellent bonding without primer, and has good UV resistance.
- Polysulfide Sealant: Designed for joints requiring prolonged immersion in liquids, provides waterproof seals, exhibits excellent chemical resistance, and performs well in submerged conditions.
What were the traditional materials used for sealing in construction?
In early times, materials like mud, grass, seeds, bitumen, tar, natural gum, and wax were used for waterproofing and sealing in construction.
What modern materials are used for sealants in construction?
Modern sealants are often made from polymers such as acrylic polymers, butyl polymers, polysulfide, silicone, and polyurethane, due to their numerous applications and superior properties.
