Most brands of cement used in concrete do not have an adhesive agent. When new concrete is added on top of old, dry concrete, the two will not come together without a binder. A binding agent acts as a glue that holds the two unrelated layers together. Unfortunately, there are some disadvantages to pouring new concrete over old concrete.
A big problem would be that it can reduce the lifespan of the area. For example, a new concrete building on a new gravel base will ensure that the structure is robust and can last up to 40 years. However, if the old concrete is not in good condition, it will significantly reduce the life of your floors over time. For large projects, coarse aggregates have large gravel and are more durable, ensuring that concrete is stronger and more durable.
In order for concrete materials to effectively bond with each other, you need to apply an adhesive adhesive agent. For this to be feasible, the contractor must pour at least 2 inches thick, use smaller aggregates, and incorporate reinforcements such as welded wire mesh or mixed fiber into the concrete. If you need to patch a concrete surface or pour new concrete over old concrete, you should invest in a strong adhesive agent and a concrete patch mixture. This is also the case with the repair and maintenance of the floor, where concrete fills the gaps resulting from damage.
There are so many concrete adhesives on the market that you can select to offer effective bonding functions. It is advisable to repair them as soon as they appear to prevent them from spreading or letting too much water into the concrete. Concrete is very heavy and has immense compressive strength, but it does not have qualities that naturally adhere to other materials. The thinnest layer of new concrete that you should apply to old concrete is about 2 to 2 ½ inches.
However, there are cases when you should never think twice about pouring new concrete over old concrete. Let's take a look at other disadvantages of using old concrete as a fill for new concrete to help you decide if it's the right choice for your project. Start by carefully sweeping away all loose stones and dirt and rinse the concrete to prepare the surface. This is not only intended to improve adhesion with the leveling compound, but also serves to seal the concrete slab underneath.