Can You Pour New Concrete Over Old Concrete?

Jul 31, 2020Concrete

One of the most commonly asked questions, we at T&T Redi Mix LLC receive is, ‘can a polished concrete floor be laid over existing concrete?’ Although we encourage customers to discuss their situations with an expert contractor, the short and quick answer to this question is yes – you can pour new concrete over the old one, considering it meets the requirements to do so efficiently.

Placing New Concrete Over Old Surface

Properly pouring new concrete over the existing slab is often more convenient and affordable. Cracking and daily wear and tear make the areas look outdated. Plus, digging up and setting a new layer requires more time, money, and energy. This is why most people prefer pouring a new layer that freshens up the existing surface. A well-laid concrete layer has a lifespan of up to 40 years. However, the right amount of prep work is crucial.

But it’s also undeniable that there are situations when starting afresh is necessary. For example, if the existing slab is worn out to the point that it’s settled at various levels or the cracks make it less functional, removing it entirely gives the concrete a more pristine look and a much stronger hold. Also, pouring new concrete over cracked, sunken, or damaged concrete indicates a shorter lifespan. If the foundation is weaker, the poured layer will rip off in just a few months. So you’d want to ensure that the root problems are first tackled.

On the contrary, if your existing concrete is stable and elevating a few inches of its height won’t hinder anything in the way, then you can certainly get new concrete poured over the old one. But make sure to leave this to professionals since you don’t directly pour the layer of concrete. You may first have to fix the problem areas of the existing slab and then bind the two with a concrete adhesive to build a functional surface.

At T&T Redi Mix, we’ve poured countless concrete mixes over the existing slabs. In our 30 years of industry expertise, we haven’t seen or layered a concrete slab that floats atop or glides off. We’ve mastered the craft, and this is also a common practice for residential or commercial parking lots, highways, or driveways. Due to reasonable costs and handiness, the method is now becoming a popular choice more than ever.

Process of Pouring New Concrete Over Old Slab

Before anything else, determining the composition of concrete is essential for going the right way from the first step. Concrete majorly comprises of cement, coarse aggregates (for thicker slabs), fine aggregates (for smaller repairs), and water. At times, it also uses slag and fly ash in place of cement, which are both recycled materials. Deciding the mineral and chemical admixtures composition also helps produce a highly workable and suitable concrete mix. T&T Redi Mix is specialized in providing ready-mix services, no matter how big or small the project is. Just let us know your requirements, and we’ll deliver you a consistent load, right at the site.  

Coming to the process, it’s quite straightforward but takes a little muscle and expertise. And here are the necessary steps:

Thoroughly clean the old concrete and sweep off all the dirt, debris, grime, or stubborn marks. Use a stiff-bristled broom, pressure washer, or commercially formulated concrete cleaner to get rid of contaminants. Also, make sure you rinse these off completely, and there are no visible or hidden particles that can hinder the pouring process.

Next, get the old slab completely wet. Since concrete is porous in nature, it’ll keep consuming water. But you need to keep spraying until the water runs off to the sides and is no longer being absorbed. This step is to lock the moisture in the old slab, so it doesn’t draw any from the new layer.

Now that the initial prep work is complete, it’s time to take accurate measurements of the space before pouring the new layer of concrete over the old one. But this isn’t important if space is considerably smaller as you can pour a small batch without setting up slab perimeters, which becomes essential for larger for enhanced precision. Measurements also allow you to gauge the amount of concrete you’ll need plus understand the length, height, and width specifications.

After this, firmly install braces that act as molds to prevent the concrete mix from spilling or making a mess. These hold the liquid right in place and as per the measurements. Use a bubble leveler to ensure the braces are sitting straight or if they need to be adjusted.

Placing a welded wire mesh between these braces is the next step to add a sturdy layer to the framework. It helps the layer of new concrete bind better to the older one.

Level the existing slab with additives and add a scratch coat. Once you’ve primed the old layer, pour the new layer of concrete as per your measurements. You can also use a concrete adhesive to help the two layers stick to each other and last longer. Being quick is the key here because we don’t want the mixture to dry or cause lumps.

In the end, the layer is smoothened out and left to air dry. And to preserve wet concrete, a curing compound is sprayed. A polyethylene sheet or concrete curing insulation blanket can also be used to cure the concrete uniformly.

The process is daunting for a first-timer, plus it also requires specialized tools and knowledge about mixing the materials. Therefore, it’s always suggested to hire professional services for commercial or residential construction projects.

Looking For Reliable Concrete Solutions? Get In Touch With Us!

T&T Redi Mix has been serving clients for three decades in and around Texas. We assure expert care, timely deliveries, and hundred percent customer satisfaction. If you want to build a superior quality concrete surface or a colored concrete for a more personalized look, we can do that for you. If you need a reliable concrete supplier, you can again count on us for that.

For more information on T&T Redi Mix and our range of concrete services, call us at (214) 785-8037 or leave your queries online.