Molds: Most concrete molds are made of urethane rubbers, which are designed to be resistant to concrete bonding. Most brands of cement used in concrete do not have a bonding agent. When adding new concrete over old, dry concrete, the two will not bond together without a binder. A binding agent acts like the glue that holds the two unrelated layers together.
Bonding adhesive will not work effectively if the concrete surface contains latitude (a dusty layer of fine aggregates and cement) or is contaminated with spills, including grease and oil. However, there are cases where you should never think twice before pouring new concrete over old concrete. You will need coarse-grained aggregate concrete if you intend to make a coarse-grained slab and fine sand or crushed stone for minor floor repairs. A bonding adhesive must first be painted over the existing concrete in order for the fresh concrete to adhere properly.
When you want to consider the exact thickness of your new concrete, it's best to look at the surrounding environment where the concrete should be. While it is possible to use old concrete as a base for new concrete, many factors will determine whether the concrete is strong enough to accommodate the new batch. Professional products backed by a national team of concrete experts to help you get every job done right. The patch or area where new concrete is added will rise compared to the rest of the house.
This bonding agent will be painted over the old concrete to ensure that the new concrete adheres successfully. If there are spills that have seeped into the floor surface, grinding or milling may be necessary to remove the upper few millimeters of the existing floor surface in order to clean the concrete. If you need to patch a concrete surface or pour new concrete over old concrete, you should invest in a strong bonding agent and a concrete patching mix. On a warm day, the existing concrete surface will be warm enough to draw water from the repair material.
In order for concrete materials to bond effectively to each other, you must apply an adhesive bonding agent. The thinnest layer of new concrete you should apply to old concrete is about 2 to 2 ½ inches. Although not the best option, adding a new layer of concrete over old concrete is still the next best option.