Once hardened, concrete is an extremely durable and long lasting construction material. However, there are things you can do to help keep it looking good.
The first thing to appreciate is that concrete is not in its self completely impermeable. Tiny holes (pores) in the concrete create a matrix of voids that allow moisture and other elements to migrate slowly through its structure. This is not a desirable quality if contaminants (particularly petroleum based products such as oils & grease) happen to drip onto the surface of concrete. The contaminant enter the void structure and become trapped within the matrix of the concrete. Cleaning becomes very difficult because although the majority of surface material is easily removed, it remains an almost impossible feat to draw out ingrained contaminants. This means that even after cleaning and scrubbing, a shadow of the contaminant usually remains. Having said this, there are many options for improving the impermeability of concrete and protecting the finished appearance.
A reduction in permeability is achieved by using higher strength concrete. Generally speaking, higher strength concretes are more dense and as a result have a smaller void structure. Other specialist cementitious based products, generally referred to as: Waterproofing Additives, can be added to standard concrete to reduce voids, increase density and improve strength.
In the context of most flatwork construction, such as: driveways & pathways, a far more cost effective means to reduce permeability and protect against staining from contaminants is to apply a simple surface coating. A surface coating (sealer) acts as a rain coat reducing the ability for water and other contaminants entering the concrete’s void structure.
Not only does a sealer provide the surface of the concrete with some protection from harsh elements, its makes the surface easier to clean, and it also helps to intensify depth of natural colours in the finished concrete that would otherwise appear dull and go unnoticed without the sealer.
For further information on the application of sealers, speak to your Concrete Contractor/Placer and get their advice. There are many products on the market and some may be more suitable for your specific project than others.