How to Pour a Concrete Curb on an Existing Slab

Pouring a concrete curb on an existing slab requires careful consideration and planning, as the lack of natural bonding agents in cement poses a challenge. Unlike new concrete, which bonds easily with fresh surfaces, the existing slab presents a different scenario. To achieve a solid connection between the two layers, you’ve two main options: using a bonding agent or opting for an unbonded overlay method. Both methods have their advantages and considerations, and understanding the steps involved in each approach is essential for a successful project.

Can You Pour New Concrete on Top of Old Concrete?

To pour new concrete on top of old concrete, you first need to ensure that the existing slab is in good condition. Any cracks or damage should be repaired before proceeding.

Before pouring new concrete, thoroughly clean the existing slab. Remove any dirt, debris, or loose material that may interfere with the bond between the old and new concrete. A pressure washer can be an effective tool for this task.

Next, apply a bonding agent to the old concrete surface. This will help to create a strong bond between the existing slab and the new pour. Follow the manufacturers instructions for the specific bonding agent you’re using.

Once the bonding agent has dried, you can begin pouring the new concrete. It’s important to ensure that the new concrete is properly mixed and of the correct consistency.

Use a float or trowel to spread and level the concrete, smoothing it out as you go. Pay attention to the edges to ensure a clean and straight finish. If necessary, use a screed to level the concrete.

Finally, allow the new pour to cure according to the manufacturers recommendations. This typically involves covering the concrete with plastic or a curing compound to prevent moisture loss. Proper curing is essential for the strength and durability of the new concrete.

By following the proper steps, you can ensure a successful and long-lasting result.

Tips for Repairing Cracks and Damage on Existing Concrete Before Pouring New Concrete.

  • Inspect the damaged concrete thoroughly.
  • Use a chisel and hammer to remove any loose or damaged concrete.
  • Clean the area with a wire brush or a pressure washer to remove dirt and debris.
  • Fill small cracks with a concrete patching compound.
  • For larger cracks, use a concrete resurfacer.
  • Smooth the patched areas with a trowel or putty knife.
  • Allow the patched areas to dry and cure properly.
  • Sand down any rough edges or uneven surfaces.
  • Apply a coat of concrete bonding agent to enhance adhesion.
  • Pour the new concrete evenly over the repaired areas.
  • Use a float or trowel to level and smooth the new concrete surface.
  • Allow the new concrete to cure according to the manufacturer’s instructions.
  • Maintain the repaired concrete by sealing it regularly.
  • Avoid placing heavy objects on the newly repaired concrete for at least 24 hours.

machinery or equipment, or simply enhancing the aesthetic appeal of a concrete surface. It’s typically applied over an existing concrete slab or substrate, and can be customized to meet specific project requirements in terms of thickness, strength, and finish. In this article, we will explore the various types of concrete topping slabs, their applications, benefits, and important considerations to keep in mind.

What Is a Concrete Topping Slab?

Installing tile or carpet, or even serving as a decorative element in a residential or commercial setting. It’s typically applied to an existing concrete slab to improve it’s appearance and functionality.

When pouring a concrete curb on an existing slab, it’s important to first prepare the surface by cleaning it thoroughly and removing any existing coatings or loose particles. This can be done using a pressure washer or a scraper, depending on the condition of the slab. Once the surface is clean and dry, a bonding agent may be applied to ensure proper adhesion between the existing slab and the new concrete.

Next, the concrete mix for the curb can be prepared according to the manufacturers instructions. It’s important to use a mix specifically designed for curbs to ensure optimal strength and durability. The mix should be poured into a wheelbarrow or mixer and combined with water until it reaches the desired consistency.

Before pouring the concrete, it’s essential to create a form using wood or metal stakes and a sturdy barrier, such as plywood or plastic. This will help contain the concrete and ensure that it cures properly. The form should be placed on the existing slab, following the desired shape and dimensions of the curb.

Once the form is in place, the concrete can be poured into it, starting from one end and working towards the other. It’s important to pour the concrete evenly and avoid creating air pockets or voids. A screed board can be used to smooth the surface and ensure a consistent thickness.

After pouring the concrete curb, it should be allowed to dry and cure for the recommended time, typically several days. It’s important to protect the newly poured curb from excessive moisture or temperature changes during this curing process. Once fully cured, the curb can be finished or sealed, depending on the desired final appearance and level of protection.

By following these steps, you can achieve a durable and attractive curb that enhances the functionality and aesthetics of your space.

How to Repair and Resurface a Damaged Concrete Topping Slab

  • Gather all the necessary tools and materials for the repair.
  • Clean the damaged area of the concrete topping slab using a broom and a pressure washer.
  • Remove any loose or deteriorated concrete from the damaged area.
  • Apply a concrete bonding agent to the cleaned and prepared surface.
  • Mix the concrete resurfacer according to the manufacturer’s instructions.
  • Apply the concrete resurfacer to the damaged area using a trowel or a squeegee.
  • Smooth out the resurfacer with a broom or a brush to achieve the desired texture.
  • Allow the resurfacer to dry and cure according to the manufacturer’s instructions.
  • Apply a concrete sealer to protect the repaired surface.
  • Maintain the repaired concrete topping slab by regularly cleaning and sealing it as needed.

Source: Concrete Topping Slab -Types, Thickness and Uses

One method to attach old concrete to new concrete is through chemical bonding. This approach involves the use of a liquid bonding agent that helps create a bond between the two surfaces. It’s important to select concrete products that are compatible with the chosen bonding agent to ensure proper adherence and longevity.

How Do You Attach Old Concrete to New Concrete?

When it comes to attaching old concrete to new concrete, one effective method is through chemical bonding. This approach entails mixing a liquid bonding agent that aids in creating a strong bond between the two surfaces. It’s essential to ensure that the concrete products you use are compatible with the specific liquid bonding agent you choose. By using compatible materials, you can maximize the effectiveness of the chemical bond.

After the bonding agent has been applied, it’s time to pour the new concrete onto the old surface. Ensure that the new concrete is freshly mixed and has the right consistency for pouring. Position the concrete formwork correctly to create a neat and tidy border for the curb.

Once the new concrete has been poured, carefully consolidate and finish the surface according to your desired outcome. Allow the concrete to cure for the recommended time, ensuring it’s hardened sufficiently before subjecting it to any heavy traffic or loads. This curing period is crucial for the chemical bonding agent to form a strong bond between the old and new concrete.

Compatibility Testing Between Bonding Agents and Concrete Products

Compatibility testing refers to the process of evaluating the interaction between bonding agents and concrete products. It’s crucial to ensure that the bonding agent selected is compatible with the specific concrete product being used.

This testing helps to determine whether the bonding agent will adhere properly to the concrete surface and provide the desired strength and durability. It also helps in identifying any potential issues that may arise during the bonding process.

Compatibility testing involves applying the bonding agent on a small test area of the concrete product and observing it’s performance. Factors such as adhesion, drying time, and compatibility with other additives or coatings are evaluated.

It’s essential to conduct compatibility testing before applying a bonding agent on an existing concrete slab when pouring a concrete curb. This ensures that the curb will bond effectively to the existing slab, preventing any detachment or failure in the future.

Ultimately, compatibility testing allows for the selection of the most suitable bonding agent for the specific concrete product and ensures a successful and long-lasting bond between the concrete curb and the existing slab.

Self-leveling concrete is a versatile material that offers a convenient solution for uneven concrete surfaces. By pouring it over existing concrete, it efficiently spreads and levels out, eliminating the need for extensive labor or floor preparations. Let’s explore the benefits and considerations of using self-leveling concrete to upgrade your concrete slabs.

Can You Pour Self-Leveling Concrete Over Existing Concrete?

Yes, you can pour self-leveling concrete over existing concrete as long as certain conditions are met. Before starting the process, it’s crucial to prepare the existing slab properly. The surface should be clean, free from dust, dirt, and debris. Any loose or damaged areas should be repaired, and any cracks should be filled with a suitable concrete patching compound.

Once the surface is prepared, it’s important to prime it with a bonding agent before pouring the self-leveling concrete. This helps promote a strong bond between the old and new layers of concrete. The bonding agent should be applied evenly and allowed to dry according to the manufacturers instructions.

Before pouring the self-leveling concrete, it’s essential to calculate the correct amount needed to cover the existing slab. This can be done by measuring the length, width, and depth of the area to be covered. It’s advisable to purchase slightly more self-leveling concrete than needed to account for any unforeseen circumstances.

To pour the self-leveling concrete, begin by mixing it with water according to the manufacturers instructions. The mixture should have a consistency similar to pancake batter. Start pouring the mixture onto the existing slab in one corner and allow it to spread and flow naturally. Use a gauge rake or squeegee to guide the flow and ensure an even distribution.

As the self-leveling concrete spreads, it will seek it’s own level, eliminating the need for extensive manual leveling. However, it’s important to monitor the process and make small adjustments if needed. Once the entire area is covered, use a long-handled trowel or a concrete smoother to remove any ridges or imperfections and create a smooth, even surface.

After pouring the self-leveling concrete, it’s crucial to allow it sufficient time to cure before subjecting it to any heavy loads or traffic. Curing times can vary depending on factors such as temperature and humidity, so it’s recommended to consult the manufacturers instructions for specific guidelines.

By properly preparing the existing concrete, priming the surface, calculating the correct amount, and following the manufacturers instructions for mixing and pouring, you can achieve a smooth, level finish that’s ready for use after adequate curing time.

How to Repair Loose or Damaged Areas on an Existing Concrete Slab Before Pouring Self-Leveling Concrete

  • Inspect the damaged areas on the concrete slab.
  • Remove any loose or crumbling concrete using a hammer and chisel.
  • Clean the area thoroughly to remove any dust or debris.
  • Apply a bonding agent to the damaged areas to promote adhesion with the self-leveling concrete.
  • Mix the self-leveling concrete according to the manufacturer’s instructions.
  • Pour the self-leveling concrete onto the damaged areas, ensuring it fills the voids completely.
  • Use a trowel or a straightedge to smooth out the surface of the self-leveling concrete.
  • Allow the self-leveling concrete to cure for the recommended time before walking or placing any weight on it.
  • Inspect the repaired areas for any imperfections and make any necessary touch-ups.
  • Once the self-leveling concrete has fully cured, you can proceed with your desired flooring installation or other project.

When it comes to the minimum depth of a concrete topping slab, it’s generally recommended to have a thickness ranging from 1 to 2 inches. However, this is only applicable if the base slab is in good condition, free from cracks, and made of high-quality, sound, and clean concrete.

What Is the Minimum Depth of Concrete Topping Slab?

When it comes to pouring a concrete curb on an existing slab, the minimum depth of the concrete topping slab is an important consideration. The recommended thickness for this type of overlay is generally 1 to 2 inches (25 to 50 mm). It’s crucial to ensure that the base slab is practically free of cracks and that the existing concrete is of good quality and cleanliness.

This bond is vital for the overall strength and durability of the curb. It’s essential to maintain the integrity of the connection between the old and new concrete to prevent future cracks or structural issues.

Having a sound and clean base slab is also essential for the success of pouring a concrete curb. If the existing concrete is compromised or of poor quality, it may affect the overall stability and longevity of the new curb. It’s important to thoroughly inspect the base slab and address any cracks or damage before proceeding with the overlay.

In addition to the minimum depth, other factors such as weather conditions, traffic load, and intended use should be taken into consideration when determining the thickness of the concrete topping slab. These factors can affect the overall strength and durability requirements. Consulting with a professional or following industry guidelines can help ensure that you’re using the appropriate thickness for your specific project.


To ensure a strong and durable bond, one must employ the use of a bonding agent or opt for an unbonded overlay method. By carefully following the appropriate techniques and utilizing the necessary materials, the process can be carried out effectively, leading to a successful integration of the curb onto the existing slab.

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