Repairing Spalled Concrete Patios: A Comprehensive Guide

Spalled concrete is not only unsightly but can also cause real problems for any concrete structure. Spalling, also known as scaling, occurs when excess water enters the concrete's structure, creating stresses that eventually cause flaking, peeling, or pitting. While small flakes of concrete may not seem like a big issue, spalling can lead to more severe structural problems if left untreated. Fortunately, repairing spalled concrete is a straightforward process that does not require a complete replacement. In this article, we will discuss the causes of spalling, the potential issues it can create, and provide a step-by-step guide to repairing your concrete patio.

Clean the slab with a pressure washer

To repair spalled concrete, you'll first need to clean the slab with a pressure washer. This is a crucial step in preparing the concrete surface for repair. Here's a detailed guide on how to effectively clean the slab:

Before starting, ensure you have the necessary safety gear, including protective eyewear, gloves, and a respirator. Concrete cleaning can generate dust and debris, so it's important to protect your eyes, hands, and respiratory system.

Begin by clearing the area of any large debris, such as rocks, leaves, or twigs. Use a broom or a leaf blower to remove these from the surface and the surrounding area. This ensures that you have a clear working space and prevents any additional dirt from being pushed further into the concrete during the pressure washing process.

Next, inspect the concrete surface for any loose debris, grease, or other contaminants. These impurities can hinder the bonding process during the repair, so it's important to remove them. If there are any visible grease stains or particularly stubborn contaminants, you can use a concrete cleaner or degreaser to help break down these substances before pressure washing.

Now, it's time to pressure wash the slab. Select a pressure washer with a strong enough psi (pounds per square inch) to effectively clean the concrete. For tough jobs, you may need a pressure washer with a higher psi, which will provide more cleaning power. Adjust the pressure and fan settings on the nozzle to suit the condition of the slab. For heavily spalled areas, a narrower fan setting and higher pressure may be required. Always follow the manufacturer's instructions for safe operation.

During pressure washing, maintain a steady pace and work in sections to ensure thorough cleaning. Start from one end of the slab and systematically move across the surface. Keep the nozzle at a consistent distance from the slab and avoid holding it too close to prevent any potential damage to the concrete. Use slow, even sweeps to ensure you're removing all the dirt and debris lodged in the concrete. Pay extra attention to areas with visible spalling, as these tend to harbour more dirt and grime.

Once you've completed the pressure washing, give the slab some time to dry. Depending on the climate and humidity, it may take several hours or even a full day to dry completely. It's important to ensure the slab is completely dry before proceeding with the next steps of the repair process.

Finally, inspect the slab again. Check if there are any remaining loose flakes or debris that the pressure washer might have missed. You can use a wire brush or a scarifier to gently remove any remaining contaminants and create a smooth surface. This step ensures that the slab is ready for the application of repair compounds and treatments.

Treat with S-1300 Pene-Krete

To repair spalled concrete, you can treat the affected area with S-1300 Pene-Krete®. This product will penetrate the pores of the concrete and provide a crystallisation that prevents water from moving through the concrete. This is achieved through a chemical reaction between the Pene-Krete and the alkali in Portland cement, resulting in the formation of a crystal-like shield within the pores. Consequently, vapour emissions are reduced, and the substrate becomes denser.

S-1300 Pene-Krete® is a non-hazardous, spray-applied penetrating densifier designed for use on all Portland cement-based substrates, such as concrete and masonry. It is essential to ensure that the surface is adequately prepared to allow the Pene-Krete to penetrate effectively.

Before applying the S-1300 Pene-Krete®, clean the slab by using a strong pressure wash. Depending on the number of loose areas, you may also need to scarify the surface. Once the slab is clean and prepared, you can proceed with the application of the S-1300 Pene-Krete®.

After applying the S-1300 Pene-Krete®, let it sit for 24 hours. Following this curing period, you can clean the surface with a pressure washer again and then begin repairing the substrate. This process involves filling any moving cracks and addressing larger holes to restore the surface to its original state.

Repair the substrate with Epoxy 300 Flex Paste

After cleaning the slab and treating it with S-1300 Pene-Krete, you can repair the substrate of your spalled concrete patio. This process involves filling in any cracks and holes to create a smooth and even surface. Here's how you can do it using Epoxy 300 Flex Paste:

First, make sure the surface is clean and free of any debris. You can use a pressure washer to clean the surface and remove any remaining loose concrete. Once the surface is prepared, you can start filling in the cracks.

Epoxy 300 Flex Paste is ideal for repairing spalled concrete because it is a flexible epoxy system with excellent elongation, hardness, and impact resistance. It forms a strong bond with concrete and properly prepared metal surfaces. The paste version of Epoxy 300 Flex is specifically designed for easy joint and crack filling.

To fill in the cracks, apply the Epoxy 300 Flex Paste into the moving cracks. Make sure to follow the manufacturer's instructions for proper handling and application. After applying the paste, immediately broadcast silica sand into it. The silica sand will provide an anchor for the resurfacer, improving the bond and durability of the repair.

For larger holes or damaged areas, you can use a product like S-7000 Underlayment or Bond-Kote. These products will help fill and level the surface, creating a smooth base for your repair. You can use a magic trowel or a large squeegee for the first coat and a flat trowel or metal squeegee for the second coat. This will ensure an even and smooth finish.

Fill large holes with S-7000 Underlayment

Filling large holes with S-7000 Underlayment™ is an effective way to repair spalled concrete patios. S-7000 Underlayment™ is a dry, pre-blended, and ready-mixed cementitious product that is ideal for patching and restoring concrete surfaces. This product is specifically designed for use as a levelling, re-grading, and sub-floor material over concrete and wood substrates.

To begin the repair process, ensure that your spalled concrete patio is clean and free of any debris. You may need to scarify the surface to create a smooth base, depending on the condition of the concrete. Once the surface is prepared, you can start filling the large holes with S-7000 Underlayment™.

S-7000 Underlayment™ is mixed with water only, making it easy to use. It can be installed at any thickness between 0 and 6 inches, providing flexibility for various repair needs. When mixed with water, it forms a cohesive bond with the concrete substrate and offers fire and water resistance. With a strength of 8,500 psi, it can withstand heavy loads while remaining resilient and flexible.

When filling the holes, use a magic trowel or a large squeegee to apply the first coat of the mixture. For the second coat, switch to a flat trowel or a metal squeegee to ensure an even finish. Finally, apply the last coat generously and use a broom to create a non-slip texture on the surface. This process will help you achieve a safe and durable repair on your spalled concrete patio.

Apply a concrete overlay

To apply a concrete overlay, you must first ensure that the existing concrete surface is clean and sound, with no loose or flaking areas. You can achieve this by using a pressure washer or a grinder to remove loose concrete and create a clean palette for applying the bonding primer. Once the surface is prepared, you can proceed to the next step.

The next step is to select an appropriate concrete overlay product. Concrete overlay products typically consist of a blend of Portland cements, various aggregates, and polymer resins, which result in a very strong and durable mixture. The specific product you choose will depend on the desired finish and thickness of the overlay. For example, if you want a smooth finish, you can opt for a micro-topping finish of 1/16" or less, while for a broom finish, you would use an overlay with a thickness between 1/8" and 3/8".

After selecting the right product, it's time to mix and apply the concrete overlay according to the manufacturer's instructions. This process usually involves mixing the product with water in a bucket and then using a trowel, squeegee, or gauge rake to apply it to the primed concrete surface. You may need to apply multiple coats or layers to achieve the desired thickness and finish. It's important to work quickly and smoothly to prevent any random show-through or weak pockets in the overlay.

Once the overlay has been applied, it will need time to cure. The curing time can vary depending on the product used and environmental factors such as temperature and humidity. After the overlay has cured, you can proceed with any additional steps, such as applying a decorative finish or a protective sealer to enhance the appearance and durability of the concrete surface.

Frequently asked questions