How to Repair Sunken Concrete

If you're dealing with sunken or settled concrete slabs, you may find yourself exploring various options for repair or replacement. In this article, we'll delve into three potential approaches to help you determine the most suitable solution for your situation. Each option has its advantages and drawbacks, and the choice between them often depends on specific circumstances.

Concrete Replacement or Repair

When faced with significantly cracked or deteriorated concrete, the option of replacing the sunken slab might cross your mind. While a new slab has its visual appeal, it's crucial to note that a freshly poured concrete slab may not precisely match the existing color or texture. Moreover, merely pouring a new slab does not address the root cause of the original cracking.

If the initial concrete damage resulted from the slab's weight, the issue is likely to recur if the underlying soil cannot adequately support the load. So, while pouring new concrete is an option, doing so over unstable soil won't effectively resolve the problem.

Mud Jacking

Mud jacking, also known as slab jacking or pressure grouting, is a common technique for lifting sunken or settled concrete. This process involves strategically drilling approximately 1-inch diameter holes through the sunken concrete slab. A grout mixture is then pumped through these holes to lift the slab from below.

Mud jacking is less disruptive than removing and replacing the slab, although both methods require a significant curing period before the area can be utilized. However, it's essential to note that the added weight during the repair might contribute to further settlement, particularly if the initial cause was incompetent soil compacting. In the case of a blowout during the pressure process, cleanup can be challenging.

Polyurethane Foam

Polyurethane foam injection involves using a closed-cell polymer foam to lift concrete slabs. Unlike open-cell foams, closed-cell foams prevent water absorption as their gas pockets are sealed off. The two-part polyurethane foam is injected through small holes in the slab, allowing it to expand and lift the concrete.

One advantage of polyurethane foam is its quick curing time—approximately 15 minutes, with the ability to bear vehicle weight in as little as 30 minutes. The foam doesn't retain moisture, is resistant to erosion, and its lightweight nature minimizes the additional load on the slab. It maintains its shape and volume over time, reducing the likelihood of new voids forming beneath the concrete.