You can pour it as thin as 1.5 inches onto old concrete. Like everything else in the world, concrete also has a useful life and wears out over time. Imperfections form when concrete hardens or sinks into the ground. Pouring fresh concrete over existing concrete is a common way to level old slabs and patch damage.
Maintain your concrete steps by sweeping and hosing them regularly to remove debris that could wear down the surface of your steps. Pouring a new layer of concrete over an existing walkway, patio or porch will raise the level by several centimeters. When the existing concrete is of the right quality, you can pour a new, thin slab over the old concrete, provided the new layer contains wire mesh or fiber reinforcement. Once you have a good batch of concrete in your wheelbarrow, spread it over the subfloor until it is smooth and even.
I started this project by pressure washing old concrete to remove all mold, dirt and loose concrete. A concrete screed is a thin concrete cement based product that is designed to be used for decorative purposes or to repair damage. But if the thickness is less than 3 inches; you need to use a bonding agent to bond new concrete to old concrete. While pavers, stones and other types of paving materials offer a more decorative look, concrete is valued for its strength and low maintenance.
Pouring the old concrete instead of having to do a demo and remove it, ended up saving the customer hundreds of dollars. Slab poured onto an existing concrete slab is more prone to frost and crack damage due to the bond between the two layers of concrete. Yes, you can put new concrete on top of old concrete as long as there are no problems such as significant cracks or frost elevations with existing concrete. Yes, if you're trying to freshen up a tired looking patio, you can cover small cracks and damage with a new layer of concrete.
Concrete that is in good condition without breakage, buckling, or large cracks can be a suitable base for a new layer. You should use a type of reinforcement, such as fiber mesh or reinforcing bar, to help control and prevent any cracks that may develop as the concrete sets. Fine sand or crushed stone is preferred for small-thickness concrete and coarse-grained aggregate is used for thicker concrete.