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What is Concrete Bonding Agent? Explain its Types and Uses

Concrete is a building material made of cement, aggregates (rock and sand), water, and additives (chemicals that enhance or modify the properties of concrete). There are a lot of chemicals used in construction now. From concrete admixtures to sealants, grouts, bonding agents, and waterproofing chemicals, the construction chemicals industry has a wide range of products. The construction industry uses these chemicals in a lot of different ways. These construction chemicals can make concrete stronger, and when used in different ways and amounts, they can also help get around many other problems. One chemical that is used in concrete is a “bonding agent.” This article will discuss concrete bonding agents and different types of concrete bonding agents.

Concrete Bonding Agent
Fig 1: Concrete Bonding Agent

What is Concrete Bonding Agent?
Concrete bonding agents are natural or man-made materials that join old and new concrete surfaces. This agent can also be used to join the concrete layers. This bonding agent helps the different concrete finishes act like a single unit. These cement bonding agents are also used to make repairs, like joining new concrete to old concrete, spraying concrete at construction joints, or using cement-sand repair mortar to make a strong bond.

Importance of Concrete Bonding Agent:
Most of the times, bonding agents are used in concrete when the old and new concrete surfaces need to be joined. It is also used to connect the surfaces of the concrete layers that go on top of each other. The main job of a bonding agent is to make the bond between the old and new concrete surface stronger. The cement in a concrete mix doesn’t have anything that naturally makes it stick together. So, when new concrete is poured over an existing layer, the two layers don’t tend to stick together. Once the first layer of concrete has hardened, the new layer will sit on top as a separate layer. It won’t make a strong bond between the two layers that come after it.

So, when the two layers don’t work as a single unit, the performance and strength of the structure will suffer. So, a bonding agent (also called a bonding adhesive) must be put on the existing concrete surface so that the new concrete will stick. It is also true for fixing floors. If concrete without any bonding agent is used to fill gaps produced by deterioration, the new concrete will not stick to the old concrete without the help of bonding glue.

Features of Concrete Bonding Agent:

Functions of Concrete Bonding Agent:
Cement in a concrete mixture does not contain any bonding agent. The two will not bond if new concrete is placed on top of an older layer. That’s why it’s important to have some bonding agent in there. Adding a bonding chemical between concrete layers makes them function like one solid slab, improving the building’s durability and efficiency. Applying a bonding agent to the concrete’s surface ensures that newly placed concrete will attach to the existing slab.

Some factors impact how well the old and new concrete bond. There are mainly two things that affect how well the old and new concrete stick together:

How to Use Concrete Bonding Agent?

The following procedure should be used for applying the bonding agent:

Types of Concrete Bonding Agent:
1. Epoxy Resin:
Epoxy Resin
Fig 2: Epoxy Resin

Epoxy resin is a concrete bonding agent widely used in construction because it is strong, doesn’t react with chemicals, and sticks well. Epoxy resin can bond to a wide range of materials as long as the surface is clean and ready. It can also be used to glue things together quickly. Some of the factors that make epoxy resin good at holding things together are:

2. Acrylic Latex:
Acrylic Latex
Fig 3: Acrylic Latex

Polymers and co-polymers of methacrylic acid and acrylic esters are called acrylic esters. Depending on the polymers used, the physical properties of acrylic latex range from soft elastomers to hard plastics. Acrylic latex is milky white and has 45% solid content. This type of latex is mostly used to connect new concrete to old concrete. It can be used as an adhesive with a brush, broom, spray, roller, or trowel or as a topping with a trowel. This emulsion is used similarly to SBR Latex in cementitious compounds.

3. Latex Emulsions:
Latex emulsions are often used as oil-in-water type emulsions in cementitious mixtures. There are three types of latex emulsions, and some of them have more than 50% water in them. Some glue can also stand up to water better than others. Latex emulsions don’t change when mixed with water and cement, but not all emulsions can be mixed with cement. So, to choose the right latex emulsion for your work, you need to know how it works from a chemical point of view.
If you use the latex emulsion agent without cement in the concrete mix, there won’t be a film at the bond interface, so the concrete will crack. Latex emulsions can be converted into functional bonding agents in the following ways:

Latex Emulsions
Fig 4: Latex Emulsions

4. Styrene Butadiene Latex:
Latex made from styrene-butadiene (SBR) is a co-polymer used safely alongside cement. Nonetheless, Styrene butadiene latex can coagulate if heated for too long at too high a temperature. Styrene butadiene latex, like acrylic latex, is a milky white color and can have a solid percentage of up to 55%. They are useful for adhering new concrete to preexisting slabs or sealing thin tops. Also, they can be used as a plaster bond in 45-60 minutes. The uses of styrene butadiene latex are as follows:

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